prove it wrong.
Plenty of people have removed the crank vent vacuum setup, but based on my research, this is a bad thing for any engine.
I am just surprised that kits like the TPO crank vent kit are still sold.
Both BCM and Jon Nichols have said the stock setup is best since it makes a vacuum in the crankcase so blowby pressure doesn't stress the engine seals and provides a reservoir in case oil is spit out the vent:
Quote from: Ducati UpNorth
The following is a earlier post by BCM Ducati:
What is different about Ducati streetbike breathers in general is that the reed valve is mounted directly in the case. The breather box location and volume are good.
The reed valve location is good for emissions but not for engine power and crankcase breathing. What happens is that under certain conditions, under high rpm and light load, the oil doesn't run back because of the reed valve and it builds up in the tube above the reed.
The simplest solution is to hollow out the reed assembly and leave it internally open but still hitched to the volume bottle. This allows the volume of the breather bottle to perform its function and usually gives a slight horsepower increase also.
Then, use either a 748RS reed valve in the airbox at the end of the breather hose, OR, use a Ford diverter valve (in-line one way) just before the airbox.
The following is a earlier post by Jon Nichols:
We firmly believe the best system is the stock system. Let me expand on this. The only part worth replacing is the breather itself, and only if it is leaking or if you want to dress-up your bike. We see many Ducati's with the K&N filter attached to the breather hose. This is simply not a satisfactory replacement or alteration to replace the stock system. The stock system is less restrictive because there is more volume making it less restrictive.
Part of the problem with this modification is that the only efficient replacement systems made were made for race circumstances. This was accomplished by increasing the tank volume into which the engine pumps. On the early bikes, 851, 888, 955 in the 851/888 chassis Ducati had a very large carbon fiber tank which was connected to the engine crankcase without any breather. The tank was mounted in the tail section of the bike. This effectively doubled the crankcase volume and was responsible for an additional 3 to 5 HP at high RPMs.
This type of system is also available for the 748/916/996 chassis. This type of system is not available for Monsters or SS models, unfortunately. Therefore, the system that allows you the largest volume to pump into is the stock system. This system pumps into the airbox and has the added benefit of a collection/separation tank between the crankcase and the airbox.
I'm with you, it will generally lower engine performance. How much for a particular engine? Who knows. I think people still love to do this mod for two reasons:
1) In the old days when smog equipment was introduced on cars almost every piece of it lowered performance.
2) The bike just looks cleaner when you take more parts off.
Scott
The TPO kit does not remove the reed valve - there is still a vacuum in the cases. It replaces the plumbing between the giant PCV and the airbox. I have seen a picture of oil all over the back wheel from removing the plumbing, but after a year and a half, it has not happened to me. I would do it again.
edit: I actually added an automotive PCV to my Aprilia that didn't have one stock and noticed an improvement.
Quote from: Bill in OKC on May 19, 2008, 09:03:40 AM
The TPO kit does not remove the reed valve - there is still a vacuum in the cases. It replaces the plumbing between the giant PCV and the airbox. I have seen pictures of oil all over the back wheel from removing the plumbing, but after a year and a half, it has not happened to me. I would do it again.
How is there a vacuum in the case if you remove the vacuum source? The TPO kit removes the hose that connects to the airbox -- which is the vacuum source.
The reed valve has nothing to do with the vacuum except to prevent backflow.
The crankcase itself has pressure, not vacuum. We hooked a meter up to it and got almost 2 bar from it (which is about 30 psi) when the engine was revved and that was on a factory version M800. I imagine the bigger bikes will produce a lot more pressure.
I'm not the expert, but the expert stories, the guys who figured this stuff out, indicate it is the positive pressure from the pistons coming down forcing air out of the valve and when they rise again a vacuum is created. After a few revolutions there is a constant vacuum in the cases.
What's the crankcase vent vacuum setup?
Quote from: Bill in OKC on May 19, 2008, 09:13:54 AM
I'm not the expert, but the expert stories, the guys who figured this stuff out, indicate it is the positive pressure from the pistons coming down forcing air out of the valve and when they rise again a vacuum is created. After a few revolutions there is a constant vacuum in the cases.
so where does blowby go?
And is it possible you misunderstood? Every source you can find on 4-cycle engine operation states that the crankcase will have a positive pressure, NOT a vacuum.
The pistons are reciprocating without a valve, so they do not affect crankcase pressure/vacuum at all. The issue is blowby. The higher the engine turning the more frequent the blowby and therefor, the more internal pressure, not vacuum, the crankcase has.
That's why engines without a vacuum hose attached (sometimes called PCV) blow their seals. If it was a vacuum, they would SUCK the seals in.
QuotePosted by: Sgt_H
What's the crankcase vent vacuum setup?
The hose on top of your engine. It is connected to a reservoir which is in turn connected by a hose to your airbox. The airbox provides vacuum to the reservoir and in turn to the crankcase to suck fumes and blowby out of the case.
(http://www.ducati-upnorth.com/tech/images/PCVConversion2.jpg)
Both of my Ducs have the stock crankcase vent system for exactly the reasons stated.
The blowby goes out the one-way reed valve the same as the positive pressure generated by the pistons falling. The one-way valve keeps air from coming back in. I can see a possible advantage having the hose going to the airbox if you have a restrictive air filter but think about this - and this does not necessarily apply to a monster but more a 999s - or anything with a pressurized airbox/ram air - what happens when you are trying to create positive pressure in your airbox at high speeds from a ram-air effect? In that case you would have a positive pressure forcing air back into the hoses.
Quote from: ducatizzzz on May 19, 2008, 11:11:56 AM
The hose on top of your engine. It is connected to a reservoir which is in turn connected by a hose to your airbox. The airbox provides vacuum to the reservoir and in turn to the crankcase to suck fumes and blowby out of the case.
Thanks, Just wanted to make sure you weren't talking about the smog canister that I just took off.
If the blowby goes through the breather, then you just contradicted what you said before -- the crankcase has positive pressure, not a vacuum
In your hypothetical of a ram-air type airbox, you would have a different kind of airbox setup and a separate pump for the crankcase, which is what F1 cars do.
Also, there are other sources for vacuum, such as having a plenum directly off the manifold, which is how Ducati does the evap emissions box for all the later bikes.
The blow-by is there whether you have a K&N or the factory setup... The whole idea is to let it out of the cases as efficiently as possible and then prevent any drawback. If I had any problem with my setup, I would be the first to admit it and change to something else. If I was really ambitious I would plumb up my O2 sensor bung and make it into an exhaust scavenger.
If you look at the factory setup for a 749/999 you'll see a pressurized airbox (ram-air snorkles connected to a sealed airbox) connected to the crankcase vent tube.
Load of BS
Check this out for the real info
http://www.ducati-upnorth.com/tech/breather.php (http://www.ducati-upnorth.com/tech/breather.php)
Quote from: Capo on May 19, 2008, 01:52:04 PM
Load of BS
Check this out for the real info
http://www.ducati-upnorth.com/tech/breather.php (http://www.ducati-upnorth.com/tech/breather.php)
that's where i got the quotes from BCM and from Jon Nichols.
Bill, maybe you can do a little more checking around, but
every reputable source I can find on the web has indicated the opposite of what you're claiming -- that the crankcase is pressured, not vacuum. If you google PCV or crankcase pressure, you'll see that the only issue is blowing seals, which is due to pressure, not vacuum. no one talks about crankcases sucking in their seals.
Seriously, just go out to your bike and hook up a flow meter to your breather. I have done it. You'll get around 20-30 psi on a new engine and more on an old one. That's air pressure, not vacuum.
Or, if you don't have a meter. Just start the bike and remove the oil filler cap. Be prepared to clean up a bit though.
Quote from: hooligan machinist on May 19, 2008, 03:44:24 PM
Or, if you don't have a meter. Just start the bike and remove the oil filler cap. Be prepared to clean up a bit though.
yeah, forgot about the numerous stories of ppl leaving their oil caps off and bathing in a shower of oil. if the crankcase had a vacuum under running conditions, that would not happen.
One of the reasons I went the K&N route was because the throttle cabling for the FCRs hit the hose. I had to remove the hose (plugged the hole with a little filter that came with the carbs) and cut away a bit of the battery box allow the cable mechanism to fit.
There's definitely some blowby around the base of the valve, but it's never been real bad, although I tend to keep the bike pretty clean so that doesn't truly tell much. Still, it's beside the point though. I would agree that routing through the airbox would be the correct thing to do, and also agree that having the valve right down on the engine doesn't make a whole lot of sense. Most likely though it was one of those necessity things with manufacturing, and probably works just fine with the stock piping (without the emissions).
It definitely would be very interesting to see a full test run. I'll also be dropping the engine on my girl here pretty soon to do some overhauling. Might thinking about fabbing up something when she goes back together. Although, you gotta admit the mini K&N does look pretty trick. ;)
Quote from: DJ on May 19, 2008, 05:57:17 PM
One of the reasons I went the K&N route was because the throttle cabling for the FCRs hit the hose. I had to remove the hose (plugged the hole with a little filter that came with the carbs) and cut away a bit of the battery box allow the cable mechanism to fit.
There's definitely some blowby around the base of the valve, but it's never been real bad, although I tend to keep the bike pretty clean so that doesn't truly tell much. Still, it's beside the point though. I would agree that routing through the airbox would be the correct thing to do, and also agree that having the valve right down on the engine doesn't make a whole lot of sense. Most likely though it was one of those necessity things with manufacturing, and probably works just fine with the stock piping (without the emissions).
It definitely would be very interesting to see a full test run. I'll also be dropping the engine on my girl here pretty soon to do some overhauling. Might thinking about fabbing up something when she goes back together. Although, you gotta admit the mini K&N does look pretty trick. ;)
I think you misunderstand what "blowby" is -- it is the gases that pass by the piston rings from the combustion chamber into the engine case. That's why the crankcase has positive pressure. In the old days, PCV was necessary because ring technology wasn't the best and you'd get gasoline vapors in your crankcase which could cause a spontaneous detonation if you didn't vent properly.
it sounds like you are just describing a leaky breather.
If you open the crankcase, there is a "snail" shape under the breather. It does not open directly into the crank galley at all.
I don't think the mini K&N looks trick, I just feel bad for the guy on the bike because it's not good for the engine.
I am not sure how much vaccum the ducati airbox can create to help evacuate the crankcase...
I think the hose is routed up to the box foremost as an EPA dump for oil blown out the crank, then it is burned instead of dumped on the ground.
mitt
Quote from: mitt on May 19, 2008, 07:10:09 PM
I am not sure how much vaccum the ducati airbox can create to help evacuate the crankcase...
I think the hose is routed up to the box foremost as an EPA dump for oil blown out the crank, then it is burned instead of dumped on the ground.
mitt
based on my flowmeter, about 1-2 bar. the connection is below the filter so it actually gets "preference" combine that with the 2-3 bar pressure from the crankcase and it does what you say.
most of what gets sucked in is combustion gases and gasoline fume, only a little oil since the reservoir condenses the oil and it drips back in.
Dang. I was just thinking about putting pod filters on the intake and a crankcase filter on the back to get rid of all that breather/airbox garbage. So you are telling me you can install the pod filters on the front either? (Because there would be no hose to the breather reservoir)
It there another choice? Like can you install pod filters in front with some hose reservoir arrangement and get rid of all that stuff? Who has examples of doing it right?
Quote from: spinned on May 19, 2008, 09:23:16 PM
Dang. I was just thinking about putting pod filters on the intake and a crankcase filter on the back to get rid of all that breather/airbox garbage. So you are telling me you can install the pod filters on the front either? (Because there would be no hose to the breather reservoir)
It there another choice? Like can you install pod filters in front with some hose reservoir arrangement and get rid of all that stuff? Who has examples of doing it right?
If you have the smog cannister connections, I bet you could rig something that way. Not sure how smart this would be as whatever comes through that hose will go into the cylinder. But the airbox connection is after the filter anyway... I no expert but I would lean towards not doing it that way. Just open the airbox lid.
Quote from: spinned on May 19, 2008, 09:23:16 PM
Dang. I was just thinking about putting pod filters on the intake and a crankcase filter on the back to get rid of all that breather/airbox garbage. So you are telling me you can install the pod filters on the front either? (Because there would be no hose to the breather reservoir)
It there another choice? Like can you install pod filters in front with some hose reservoir arrangement and get rid of all that stuff? Who has examples of doing it right?
plenty of people do this, and i assume they throw out the breather apparatus. i think chris at ca-cycleworks has a kit for it, but i assume it is "for race use only" since your race engines are getting rebuilt frequently, the seals are not an issue.. he might have some good input on this subject too, btw.
The open airbox should give you the same flow as pods, or better. the main reason to use pods in my book is if you switch to the short manifolds and can't use the stock airbox at all.
Quote from: Sgt_H on May 20, 2008, 05:12:25 AM
If you have the smog cannister connections, I bet you could rig something that way. Not sure how smart this would be as whatever comes through that hose will go into the cylinder. But the airbox connection is after the filter anyway... I no expert but I would lean towards not doing it that way. Just open the airbox lid.
what comes out of the breather should only be fumes, since all the air comes through the air filter first. thus, anything sucked back into the intakes will be fumes or oil vapor, but no debris. if you had it going through the filter, it would foul the filter.
back when i built VW drag engines, i would sometimes run the breather hose through an in-line filter. we were required to use PCV for environmental reqs (even in the 80s) and most guys just ran it directly to an intake manifold. i found an in-line PCV filter and then ran it to the manifolds through a T, which seemed to work better. The in-line filter would get oil fouled after 2-3 races.
seems you could pick up one of those and run it to the manifolds with the pod filters. probably would need tweaking a lot since pulling directly to the manifold is tricky.
Our V twins, unlike a typical car engine always have positive crankcase pressure, the question is how much? Loose the breather box and there will be an increase in pressure. Anyone notice the Corsa breather box for super bikes is larger? This is to reduce pumping losses. This increase will result in a minor power loss and reduce the ability to remove blow by gasses from the engine. IMO, a breather boxectomy is needed for certain modifications like pod filters, but otherwise, why do it?
Quote from: ducatizzzz on May 19, 2008, 02:29:11 PM
Bill, maybe you can do a little more checking around, but every reputable source I can find on the web has indicated the opposite of what you're claiming -- that the crankcase is pressured, not vacuum. If you google PCV or crankcase pressure, you'll see that the only issue is blowing seals, which is due to pressure, not vacuum. no one talks about crankcases sucking in their seals.
Vacuum is a relative thing in this thread - the whole goal of this entire thread is to discuss REMOVING the pressure from the crankcase. Do you understand why there is a one-way valve in the crankcase breather? If you did then you would know why the bike runs worse without it. If there was NEVER a vacuum in the crankcase - the one-way valve wouldn't be needed would it? Why do you suppose Ducati added the restriction of a reed valve in the breater hose? Why do you think engines start leaking oil through their seals without this valve? If you think the small amount of vacuum generated by an airbox with a lot of restriction can come anywhere near the amount of force generated by blowby and the pumping action of the pistons then you are wrong. The 999 has a pressurised airbox but the pumping action of the engine/crankcase is enough to overcome it.
I just like the naked look. How can you remove the most stuff and have it not effect the performance. Pod filters would remove a lot and look cool too. Removing the oil breather reservoir would open thing up too. But if you are saying that would screw up the crank then I will back away from that idea. I have seen a lnumber of Ducati threads on Pod filters and I have never heard this would be a problem with the crank....
All well and good, but when tuners like BCM, Jon Nichols and MBP line up against removing the breather apparatus, you have an uphill issue of proof.
I started this thread with "prove it wrong." Lots of opinions and no one's offered another tuner on par with BCM or the others who says otherwise.
Having a vacuum assist on the breather IS a good thing for all out performance. I did weigh the pros and cons and decided the TPO kit was the right way to go for my bling lust. If I start getting oil on my back tire I'll reconsider [beer]
The crankcase definitely develops pressure, however, as noted in the article, except for the advantages of emmisions, and oil conservation, opening the crankcase to atmosphere is most beneficial. This is what you're doing when remove the cansiter, and drill out the reed valve. This is how all performance auto engines were run until emissions restrictions were put in place barring it.
The idea here is that combustion force has to fight crankcase pressure to push the piston down the bore. If you vent the case, there is no pressure built up. You have the best case scenario for power loss, as well preventing seal blowout. Running an open vent in the crankcase is the ideal setup, except for the "emissions issue" I tend to think that a little bet of oil vapor isn't going to harm the enviroment, we're not talking about burned or unburned hydrocarbons here, just a little petrolium. So outside of emissions concerns, the problem with running a completely open vent on the Ducati motors really boils down to oil loss. Due to the location of the vent, the Ducati motors have a tendancy to spit oil out the vent, and more alarmingly, onto the rear tire.
As also mentioned in the link article, this was a pretty minute problem except in the case of long very high rpm runs, and wheelies. The wheelie problem is easily solved by leaving the hose in place, and mounting the filter up high in the frame, so that oil will not be able to run out of the crankcase when it is tilted back.
Justin
On Mine I have the STM Crank case breather with the reed valve.
(http://i28.tinypic.com/330veo3.jpg)
The reed valve makes a little flapping noise in there but it definietly lets pressure out.
I removed the intermediate breather box under the tail and routed some clear plastic hose directly to the airbox, via under the tank.
It cleans things up some and I know where the vapors go.
Quote from: ducatizzzz on May 20, 2008, 09:33:16 AM
All well and good, but when tuners like BCM, Jon Nichols and MBP line up against removing the breather apparatus, you have an uphill issue of proof.
I started this thread with "prove it wrong." Lots of opinions and no one's offered another tuner on par with BCM or the others who says otherwise.
I attended a couple of maintenance seminars at BCM. Bruce did say that there was a theoretical gain to be had by increasing the vacuum in the crankcase, but he qualified it also by saying that you'd not notice the difference in our bikes.
Quote from: ducatizzzz on May 19, 2008, 07:13:56 PM
based on my flowmeter, about 1-2 bar. the connection is below the filter so it actually gets "preference" combine that with the 2-3 bar pressure from the crankcase and it does what you say.
most of what gets sucked in is combustion gases and gasoline fume, only a little oil since the reservoir condenses the oil and it drips back in.
Are you suggesting that the vacuum in the airbox is 1-2bar? This (2bar) equates to over six FEET of water or 200,000 pascals (incidentally bar is not typically used as a unit of measure for vacuum), if this was the case, what would the vacuum be below the throttle bodies?
also, a flow meter measures flow, a pressure gauge measures pressure, compound gauges measure vacuum and pressure, the preferred (and more accurate) instrument is a manometer.
The volume in the crankcase varies, as does the conditions for leakage past the rings.
The 'breather box' or 'reservoir' is actually a inertial separator that serves to reduce the velocity and cause a change in direction of the gas, this will remove most of any oil entrained within the gas stream, the removed oil collects in the bottom of the separator and drains back into the engine when conditions permit.
May I suggest that you run your tests again, only this time use the correct instrumentation, simultaneously measuring crankcase pressure, the pressure at the separator, the vacuum in the airbox and the vacuum below the throttle body, do this at 1000rpm increments from idle to max. This may give you the proof you seek.
Quote from: Capo on May 21, 2008, 03:08:24 AM
Are you suggesting that the vacuum in the airbox is 1-2bar? This (2bar) equates to over six FEET of water or 200,000 pascals (incidentally bar is not typically used as a unit of measure for vacuum), if this was the case, what would the vacuum be below the throttle bodies?
also, a flow meter measures flow, a pressure gauge measures pressure, compound gauges measure vacuum and pressure, the preferred (and more accurate) instrument is a manometer.
The volume in the crankcase varies, as does the conditions for leakage past the rings.
The 'breather box' or 'reservoir' is actually a inertial separator that serves to reduce the velocity and cause a change in direction of the gas, this will remove most of any oil entrained within the gas stream, the removed oil collects in the bottom of the separator and drains back into the engine when conditions permit.
May I suggest that you run your tests again, only this time use the correct instrumentation, simultaneously measuring crankcase pressure, the pressure at the separator, the vacuum in the airbox and the vacuum below the throttle body, do this at 1000rpm increments from idle to max. This may give you the proof you seek.
1-2 mbar vacuum at the airbox and 2-3 bar pressure at the crankcase at 4500 rpm. Manometer on the airbox and flow meter on the crankcase. Was typing while multitasking.
Quote from: MendoDave on May 20, 2008, 02:56:52 PM
On Mine I have the STM Crank case breather with the reed valve.
The reed valve makes a little flapping noise in there but it definietly lets pressure out.
I removed the intermediate breather box under the tail and routed some clear plastic hose directly to the airbox, via under the tank.
It cleans things up some and I know where the vapors go.
The flapping noise is the valve snapping shut when the pistons rise on the exhaust and compression strokes. It creates a kind of a ?pre-evacuation? or temporary vacuum on the compression and exhaust strokes to get ready for the next intake/power/blowby stroke. It is a really ingenious little performance trick. Most meters that I am familiar with will give you an average reading - not the instantaneous readings that would be needed to see the difference in crankcase pressure between a power stroke and a compression stroke - a reed valve is very sensitive to these changes.
Now on the compression & exhaust stokes the other piston is in the middle of doing something else. Is it 90 degrees different on the 2v engines? or 180?
Quote from: MendoDave on May 21, 2008, 03:30:11 PM
Now on the compression & exhaust stokes the other piston is in the middle of doing something else. Is it 90 degrees different on the 2v engines? or 180?
90 degrees - common pin.
when the vertical cylinder piston is at TDC (zero veloicty), then the horizontal cylinder is close to its maximum velocity (half way between TDC and BDC).
mitt
So if one Piston is making vaccum on the compression stroke then the other one is starting to make pressure...
(I could sure use spell check)
Quote from: MendoDave on May 21, 2008, 05:01:15 PM
So if one Piston is making vaccum on the compression stroke then the other one is starting to make pressure...
Correct, Ducati V-twins fire every 450°. (this is easier thought of in terms of 180°, while one cylinder fires, the other is compressing the exhaust stroke.)
i can't say that i have the experience of BCM or Nichols and wish i could comment on the positive/negative affect of the breather debate. I find this thread fasinating.
RB
"Crankcase vent vacuum setup removal = bad" because it makes my head hurt.
If you can vent the crankcase, contain any oil that is spewed out, and have it drain back into the case, that would be the simplest solution. You could get fancier and add a vac bung to the exhaust and actually use the exhaust to pull a vac on the crankcase. We used to do this all the time on high-po import motors (2.1l's spinning to 12k rpm and making over 270whp) and it was worth about 12 hp off the top of my head. Potential problems include backfires into the case/block (eliminated with a check valve) and sucking oil out of the case/block (obviously bad).
The stock system on the 999 has a large breather box to increase the volume and also to keep (or attempt to) oil from finding it's way up the vac hose into the airbox. Never has on my bike, but I've heard/seen it happen to others. Simple setup I've used many times on auto's is to fab up a catch can, vent the case/block to the can, and a hose goes from the can to a vac source before the TB (airbox). Fill the can with steel wool to trap/keep any vapors. We'd actually tap the block and run another line from the bottom of the catch can back into the block to allow another vent/oil drain path. Now it auto-drains and it almost maintenance free.
Like BCM, without some testing I'd be suprised to see if a constant vac system would be a benefit to our motors. Might make a horse or 3, but if it did you'ld see it used in WSBK. Probably the benefits (a pony or 3) arn't large enough to outweight the drawbacks (more complication...and most importantly...weight).
Hows that for a first post? :D
Thank god there is alternative to VS now :)
Quote from: TAftonomos on May 23, 2008, 07:48:56 PM
Hows that for a first post? :D
Thank god there is alternative to VS now :)
Excellent [thumbsup]
One thing I didn't remember to put is the reason you don't want oil/oil vapor in the airbox. On a normalcompression bike or stock one, it shouldn't/won't matter. Raise the compression and you might see a difference in the amount of timing you can/can't run.
Explanation - Oil vapor LOWERS the octane rating of the gas you buy. It will cause the mixture to burn faster (lower octane), possibly causing pinging/detonation. To counter this, less timing will be run, potentially robbing the midrange of some power and the "snap throttle" drive ability all twin guys like. Soggy would be a better way to describe it.
All of the above will also be affected by combustion chamber shape, piston shape, squish area, and the like. Until its a built motor and it pings, you should be fine with the stock system. Another trick I've seen is mounting a corsa reed valve in the airbox, removing the reed in the breather assembly, and running the hose in that way. Lots of ways to skin a cat that may or may not need skinning if you catch my drift.
I'm out....off to ride a s2 and a s4 and see which one I like better :D
Been reading this, because:
A: The hose between my canistor/seperator box (under the seat) broke off. So I plugged it and have an open hole at the canister now, filled with a filament material from work.
B: Have thought about going to the K&N assy mounted up high, but was talked out of it by a reliable source.
Currently using the STM breather assy, does it offer or change my options?
A side note: If your bike (not mine) has a forced air induction. Does that not pressurize the airbox? And if the airbox is pressurized, how would the hose assy for the crankcase pull vacuum unless it is located where a venturi effect could take place? Confused on that one. More of a gearhead, than being able to understand the airflow aspects of it. ;)
Quote from: printman on May 24, 2008, 06:40:55 AM
Been reading this, because:
A: The hose between my canistor/seperator box (under the seat) broke off. So I plugged it and have an open hole at the canister now, filled with a filament material from work.
B: Have thought about going to the K&N assy mounted up high, but was talked out of it by a reliable source.
Currently using the STM breather assy, does it offer or change my options?
No, the STM breather is just a high-quality, bling version of stock. Same reed setup and better sealing at the base.
QuoteA side note: If your bike (not mine) has a forced air induction. Does that not pressurize the airbox? And if the airbox is pressurized, how would the hose assy for the crankcase pull vacuum unless it is located where a venturi effect could take place? Confused on that one. More of a gearhead, than being able to understand the airflow aspects of it. ;)
Depends on the type of system, but generally you would have a compltely different setup.
Quote from: printman on May 24, 2008, 06:40:55 AM
A side note: If your bike (not mine) has a forced air induction. Does that not pressurize the airbox? And if the airbox is pressurized, how would the hose assy for the crankcase pull vacuum unless it is located where a venturi effect could take place? Confused on that one. More of a gearhead, than being able to understand the airflow aspects of it. ;)
You would then take vac from the turbo inlet, as you stated correctly that the airbox would be pressurized.
I like reviving old debate threads.
I am planning on building an aluminum catch can of sorts for my breather. Most likely it will be around 1-1.5 quatrs. I cant remember how big the stock setup is.
Interesting thread.
I think the crankcase reed valve is a good idea. At some point the case must experience both a positive pressure and a vacuum. Hence the need for a reed valve. I think I'll trust the designers on this and leave that be.
My only guess for the pass through box by the shock is to reduce the pulsations that may be created under positive crankcase pressure to the airbox. Possibly to cool the oil vapor and drain some back to the sump but not likely. It's behind the motor and not very cool. If this were the case it would be up front. I can think of no better way to reduce pulsations to the airbox than to not have it go there at all. The atmosphere around me would be fine.
Having the crankcase oil vapor go to the airbox is a neat way to make sure an otherwise possibly messy situation stays clean. Also to satisfy smog. A good filter with proper maintenance should take care of this nicely (the mess that is, screw the smog stuff).
I'm not reclaiming any oil or anything by having it go to the airbox. That gets burned. So I'm taking oil vapor and mixing it in with my fresh air, thereby richening the mixture, but not in a good way. The oil is hard to burn, doesn't flash well. Flame propogation sucks. Little droplets get trapped at the edges of the combustion area causing dead spots. Worse yet, they interfere with the fuel burning. So I think if I plug that hole in the box I'm going to lean it out. It'll probably be minor and can be corrected with a jetting adjustment, which I'll do when I put the FCR 41's on there.
So at the end of the day I think I'll wind up with the aftermarket reed valve and a K&N on a bracket where the current little box by the shock is.
Interesting thread though. Lots of opinions on this topic.
Quote from: JimE on August 06, 2009, 10:55:25 PM
I'm not reclaiming any oil or anything by having it go to the airbox. That gets burned. So I'm taking oil vapor and mixing it in with my fresh air, thereby richening the mixture, but not in a good way. The oil is hard to burn, doesn't flash well. Flame propogation sucks. Little droplets get trapped at the edges of the combustion area causing dead spots. Worse yet, they interfere with the fuel burning. So I think if I plug that hole in the box I'm going to lean it out. It'll probably be minor and can be corrected with a jetting adjustment, which I'll do when I put the FCR 41's on there.
So at the end of the day I think I'll wind up with the aftermarket reed valve and a K&N on a bracket where the current little box by the shock is.
Interesting thread though. Lots of opinions on this topic.
yes, lots of opinions.. all the builders who don't sell a kit to remove it are saying leave it on, whereas the guys who sell a kit are saying to remove it! Having BCM, et al, say it is better to leave it on pretty much does it for me. they don't get anything for offering that opinion. if they wanted to make a kit and sell it, you can bet ppl would line up for it if they recommended it.
the amount of oil vapor that ends up in the airbox is nil or practically nil. check it for yourself. the way the stock system is set up, the oil vapor cools and liquifies before it reaches the airbox (which is why there are multiple chambers in the system). airbox provides vacuum, pulls the crank air. oil vapor travels up the tube and begins too cool immediately, by the time the air reaches the second chamber of the first breather box (look under the seat, it is bifurcated), all the oil has pretty much liquified and stays there. if you remove that hose, the oil droplets will come out.
when the reed is under pressure (i.e. case pressure or vacuum) , the outside expands and prevents liquid from reentering, but when the engine is off and there is no moving air, the outside relaxes and the oil can reenter.. pretty neat setup.
Your Duc engine always has positive pressure. This is due to piston size as compared to crankcase volume. This is why you have a one way valve out and no way for air to enter your crankcase like you do on your car. The breather box is a rather large area with some negative pressure to help relieve crankcase pressure and store the vapors until they can be burned by the engine. Removal of this box makes your system a little less efficient. The only reason to remove this box, IMO, is to allow other modifications.
I looked at the breather box a while back and didn't like the location or size. I also didn't like the hose constriction, as the crankcase flow starts on a .75" hose and gets to the airbox on a smaller hose. Actually built a fiberglass breather box to fit on the area under the cowling but the two .75" hoses made the thing ungainly.
Ended up with a Nichols breather and a .75" hose going to the rear and a second one way valve on the hose by the beer tray, with the hose venting at the rear. The reed valve in the breather is not a full one way valve, as it must let the condensed or expelled oil back into the crankcase. On my bike some of the oil vapor/mist collects on the hose and drains back into the crankcase through the Nichols breather. The second one way valve at the rear handles mostly vented gas. I wish there was more air volume capacity on the hose but like all else on my bike, it is a compromise. The location on the original breather box was replaced by a better voltage regulator mount.
I'd like to remount my regulator for better cooling but don't want a Nichols or similar with the breather filter element. Maybe routing the hose a little further as mentioned above is an option. I'll have to take a look and consider that. I think the only reason the stock breather box is so big is to fit a little maze inside. Fumes escape to the air box but liquid oil droplets hit a vane of some sort and drip back to the case.
Scott
QuoteI am not sure how much vaccum the ducati airbox can create to help evacuate the crankcase...
I think the hose is routed up to the box foremost as an EPA dump for oil blown out the crank, then it is burned instead of dumped on the ground.
mitt
Reply from Shyster:
Quotebased on my flowmeter, about 1-2 bar. the connection is below the filter so it actually gets "preference" combine that with the 2-3 bar pressure from the crankcase and it does what you say.
most of what gets sucked in is combustion gases and gasoline fume, only a little oil since the reservoir condenses the oil and it drips back in.
Shyster, this is a good thread and I'm glad it got revived. In re-reading it I think it's time for some definitions and basic physics, especially since you corrected someone else for misusing the term 'blowby'. First, flowmeters measure flow, either mass or volume flow, as in pounds per hour or say liters per minute. Pressure gauges measure pressure as in psig or psia. If you actually had a pressure gauge rather than a flowmeter hooked up to your airbox and measured 1-2 bar of vacuum something is wrong. A bar is about 14.5 psi and a perfect vacuum at sea level is about 14.7 psi. No way to get to 2 bar of vacuum or even measurably above one bar and specialized vacuum pumps take a long time to pump even a small sealed container down to near to absolute vacuum. My point is not necessarily to be critical, just to point out that if you are to challenge others to prove you wrong, you at least need to get your ducks in a row with basic terms and numbers correct. :)
Quote from: Langanobob on August 07, 2009, 04:10:02 PM
Reply from Shyster:
i didn't do it myself -- well, all alone that is. i'll see if i can get Todd to come on here and explain it or at least post his actual method and measurements he got off my bike (a '95 900SP with lots of mods). i helped. ran it up on the dyno, and sat on the bike while he hooked it all up and spun it up myself. it was actually his idea because we had been talking about blowby and the effects of positive crank ventilation. we are both engineering nerds, except that i went into law after college and he stayed in engineering. tune in again later...
Saw this, and might have some pictures to add in the next week or so. I'm making a new breather box out of composite to fit under the solo DP seat. I will use a corsa reed valve mounted in the airbox, and a billet breather where the stock one goes with the reeds removed. This will allow oil to drain back out of the catch can much easier, and allow a larger breather box to be used. The stock breather box won't really work with my new subframe, which is why I ended up needing to fab a new one.
Thinking of this, I just did it. Got a nice little stainless filter for the end of the breather hose, used a plastic radiator drain plug at the airbox hose fitting, then fabbed a little bracket to support the filter, attached it to the end of the hose, attached the bracket to the forward bolt hole from the old box, and safety wired the filter to it.
Works like a charm. About 500 miles and nary a drop of oil out of it. Np performance difference I can tell. My bike does a lot of starting and stopping and lot of around town with bursts of freeway and twisties in between. I'm on the throttle a lot and starting from cold a lot. Cost about $18 in parts with my account.
So I dunno what you guys are talking about. Works fine for me.
Cheers,
Jim
Quote from: JimE on August 15, 2009, 09:42:28 PM
So I dunno what you guys are talking about. Works fine for me.
Cheers,
Jim
Sure, and a car will run fine with water in the crankcase for a while... [thumbsup]
Volvo Cash for Clunkers Engine Disabling (http://www.youtube.com/watch?v=waj2KrKYTZo#lq-lq2-hq-vhq)
That's a clunker?
Quote from: ducpainter on August 16, 2009, 04:51:49 AM
That's a clunker?
<OT>
YEP.
Plenty of vids on youtube showing awesome looking cars being trashed.
Quotei'll see if i can get Todd to come on here and explain it or at least post his actual method and measurements he got off my bike (a '95 900SP with lots of mods).
Thinking about it later, I probably got confused over the term "bar" which is a well defined engineering pressure unit. He may have meant the scribed lines or "bars" on the scale on a manometer or something else. Hope I didn't sound critical, sometimes there's a thin line between confused and critical. :)
This thread surfacing again got me thinking. The pic below shows traces of the vertical cylinder in blue, horizontal in green and combined volume in red (based on 992cc). S is spark, C is compression stroke, P is power stroke, E is exhast stroke and I is intake stroke. The combined volume basically indicates the approximate volume (con-rods and so forth not considered) in the cyclinders on the crankcase side during an engine cycle (duc motor). You can see that the total volume under the pistons fluxuates by about 650cc. One thing to note is that the intake strokes take place mostly during the period when crankcase volume is being decrease by piston motion. This would suggest that connecting the crank breather to the airbox would lead to the assistance, by intake "suction", in evacuating the pressurized crankcase gas created by decreasing the volume of the crankcase.
(http://i41.photobucket.com/albums/e297/pennyrobber/misc/crankcasevolume2.jpg)
I like your diagram. Don't forget that Ducati (and others) sell a few high performance bikes with ram air pressurized air boxes - not the Monster though AFAIK. The pressure in the airbox will increase as the bike's speed increases and so presumably when you need crankcase evacuation the most, you would have just the opposite. I'm pretty sure Ducati engineers must have taken this into account when connecting the crank breather to the airbox if it meant gaining or losing a pony or two.
Quote from: Bill in OKC on August 17, 2009, 01:43:49 PM
I like your diagram. Don't forget that Ducati (and others) sell a few high performance bikes with ram air pressurized air boxes - not the Monster though AFAIK. The pressure in the airbox will increase as the bike's speed increases and so presumably when you need crankcase evacuation the most, you would have just the opposite. I'm pretty sure Ducati engineers must have taken this into account when connecting the crank breather to the airbox if it meant gaining or losing a pony or two.
Exactly. As you turn the throttle, intake vacuum decreases. So the notion that this system works entirely off vacuum is false when talking about higher RPM's. However, as there clealy is air flowing through the air box during any engine RPM, and increasing as RPM increases, there is a venturi effect that would still pull vapors from the storage tank into the air box.
To accurately make a call on whether or not you're actually gaining any benifity from having this system on or off the bike, you'd need to know a few things. Pressure in the crank case, pressure in the hose going to the air box (remember, vacuum is simply pressure less than atmospheric), and the calibration force of the reed valve. As already noted, the pressure in the crank case is going to be consistantly changing; it increases as the piston moves down the cylinder, and decreases as it moves up. Thus, when RPM increases and the frequency of this pressure change becomes greater, the crankcase pressure would essentially "stabilize." In any case, I'd almost bet my bike on the fact that the spring tension which the reed valve opens at is far less than the pressure needed to blow out the engine seals (when not excessively worn).
IMO, there have been enough people who've piled on plenty of miles with the system removed that if you want to go with that route, then do just that. But, for now, I'll keep mine hooked up. If for some reason something on the system failed (say the tank cracked as I've seen on a few monsters I looked at), it'd probably come off as I'm sure the part is quite expensive
Quote from: chris1044 on August 17, 2009, 05:05:59 PM
If for some reason something on the system failed (say the tank cracked as I've seen on a few monsters I looked at), it'd probably come off as I'm sure the part is quite expensive
as the system is part of the emissions system, it's warranted under the 5-year emissions warranty.. it would be replaced if it cracked due to manufacture or design..
So after 5 pages of comments, the gist can be summed up thusly:
1. Leave the crankcase vent box thingy on your bike.
2. Who cares, take it off.
And the argument for each is that something in theory will happen, even though no one seems to have exact stats that show how much of something. They have numbers, charts and figures that dance around something and prove part of something. But no one seems to be able to definitively prove:
That taking the box off gains or loses horsepower or reliability.
It does, however, mess with the EPA-approved emissions controls. And since everyone leaves the charcoal canister on their bike, that would be reason enough to keep it on there. Oh wait, no one leaves that on there...
Precisely...
Manifold vacuum, now called absolute pressure is highest when the throttle is closed and reduces as the throttle is opened, and, in some engines will have no vacuum at wide open throttle.
Ported vacuum is at the throttle plate and is 0"Hg when the throttle is closed and increases as the throttle is opened.
Venturi vacuum is the negative pressure (vacuum) created within the venturi (restriction) and increases with the speed of airflow. Negative pressure in your air box is created by venturi vacuum.
QuoteVenturi vacuum is the negative pressure (vacuum) created within the venturi (restriction) and increases with the speed of airflow. Negative pressure in your air box is created by venturi vacuum.
Howie, seems to me that air box vacuum is created by the pressure drop across the filter and pressure drop across the airbox inlet nozzle. I thought that venturi vacuum is localized at the venturi?
Also, (aaargh) what about the Helmholtz (?) resonance that is supposed to create a positive airbox pressure due to reflected pressure waves from the intake valve closing and opening. Wonder how those pressure waves interact with the crankcase pressure from pennyrobber's chart? My suspicion is that the crankcase pressure itself is enough to sufficiently vent the crankcase, even against any positive pressure from the airbox pressure waves and that any vacuum effect from the air box is minimal.
Seems like someone here, maybe Speeddog, knows about the Helmholtz airbox pressure pulses. I sure don't.
Quote from: Langanobob on August 17, 2009, 10:53:20 PM
Howie, seems to me that air box vacuum is created by the pressure drop across the filter and pressure drop across the airbox inlet nozzle. I thought that venturi vacuum is localized at the venturi?
Also, (aaargh) what about the Helmholtz (?) resonance that is supposed to create a positive airbox pressure due to reflected pressure waves from the intake valve closing and opening. Wonder how those pressure waves interact with the crankcase pressure from pennyrobber's chart? My suspicion is that the crankcase pressure itself is enough to sufficiently vent the crankcase, even against any positive pressure from the airbox pressure waves and that any vacuum effect from the air box is minimal.
Seems like someone here, maybe Speeddog, knows about the Helmholtz airbox pressure pulses. I sure don't.
You are correct about airbox vacuum, I was just trying to keep things simple. It was also 1:47:14 AM here in Da Bronx. Crankcase pressure will sufficiently vent the crankcase as long as the hose from the valve is not dumping into positive pressure, like in the old days before positive crankcase ventilation became mandatory on cars. Back then, your car had an oil filler cap with a filter in it and a road draft tube that was cut in such a way that passing air would create negative pressure. You could probably rig something like that on your Duc, but I imagine it would probably be quite ugly. Engines actually prefer a slight negative crankcase pressure but achieving this on a Ducati engine without a ridiculously large crankcase would be quite a task, as illustrated by pennyrobber's chart. In the case of our Ducs, the crankcase valve controls the amount of positive pressure. The more you reduce the pressure where the vapors go, the more you can reduce crankcase pressure. As far as your question about the Helmholtz (you spelled it right) resonator effect goes, I think you would need to put your air box on a flow bench to find out. AFAIK, in the case of your bike the main purpose is noise canceling, but would have an effect.
Typically, a modern car engine PCV system consists of a hose from a valve cover to the air cleaner that will supply clean air as needed and another hose from the valve cover or crankcase to manifold vacuum through a small fixed orifice or PCV valve to control crankcase pressure, and, if all is good you have a slight negative pressure.
QuoteTypically, a modern car engine PCV system consists of a hose from a valve cover to the air cleaner that will supply clean air as needed and another hose from the valve cover or crankcase to manifold vacuum through a small fixed orifice or PCV valve to control crankcase pressure, and, if all is good you have a slight negative pressure.
Howie, I have an old '66 Triumph Bonneville that used to be my daily rider. It of course leaked oil and years ago I experimented with a small car type PCV valve from the crankcase to the intake manifold. The Triumph motor came with some kind of really inefficient rotary valve for crankcase venting and IIRC I took it out all together and just ran a crankcase vent port straight to the PCV valve. I thought it might foul plugs, but no. It's worked perfectly for a long long time. Amazingly the bike no longer leaks any oil at all during the summer when the motor is running a lot but during winter storage it still develops a good sized puddle under it.
I've never quite grasped the concept of "If it ain't broke don't fix it" and I've thought about experimenting with something similar in the way of a PCV valve on my Monster but it probably will be a long time before it reaches the top of the priority list.
Charcoal canister is not EPA it is for CARB. Everyone not in cali can legally remove it. The crank vent is EPA.
(http://i99.photobucket.com/albums/l309/ducatiz/DML/cali.jpg)
Quote from: ducatiz on August 18, 2009, 06:26:31 AM
Charcoal canister is not EPA it is for CARB. Everyone not in cali can legally remove it. The crank vent is EPA.
Touché, Ducatiz
Quote from: Langanobob on August 18, 2009, 06:00:34 AM
Howie, I have an old '66 Triumph Bonneville that used to be my daily rider. It of course leaked oil and years ago I experimented with a small car type PCV valve from the crankcase to the intake manifold. The Triumph motor came with some kind of really inefficient rotary valve for crankcase venting and IIRC I took it out all together and just ran a crankcase vent port straight to the PCV valve. I thought it might foul plugs, but no. It's worked perfectly for a long long time. Amazingly the bike no longer leaks any oil at all during the summer when the motor is running a lot but during winter storage it still develops a good sized puddle under it.
I've never quite grasped the concept of "If it ain't broke don't fix it" and I've thought about experimenting with something similar in the way of a PCV valve on my Monster but it probably will be a long time before it reaches the top of the priority list.
Interesting. Did, or was the Triumph supposed to be slight negative crankcase pressure out of the factory? It seems to me like it could work, the hard part would be designing a liquid separator. A properly sized fixed orifice might work as well, and would be simpler. Because Ducati doesn't do it doesn't mean it can't be done.
QuoteDid, or was the Triumph supposed to be slight negative crankcase pressure out of the factory?
The original Triumph vertical twins were kind of interesting. Both of the pistons went up and down together, one going up on the compression stroke while the other was going up on the exhaust stroke. But coming down together they must've built up a heckuva crankcase pressure. The engine was also dry sump, wherever that might fit into the equation. As I recall the rotary valve was timed to be open when the pistons were coming down and closed coming up, or at least that's what common sense tells me, not so much memory as it was a long time ago last I had the motor apart. I don't know if there was any cam timing type of overlap in the rotary valve operation. So, I guess if that rotary valve was effectively closed it would pull a good vacuum with the pistons going up so that could've minimized the positive pressure build up going down.
But the end result was that there was positive crankcase pressure that made for the famous Britbike oil puddles. After the PCV valve installation, no more puddles.
Thanks. I was familiar with all but the rotary valve. I've often wondered why Ducati doesn't use dry sumps since this also helps prevent oil starvation
Quote from: howie on August 18, 2009, 06:15:10 PM
Thanks. i was familiar with all but the rotary valve. I've often wondered why Ducati doesn't use dry sumps since this also helps prevent oil starvation
Ducati is probably in kind of a bind in terms of changing the engine design.
On the one hand, Ducati purists would shit (and not just purists, even the weekend purists would shit). Look what happened when they updated the frame on the 696. Shit storm. It's not like Ducati used a trellis frame on every bike, nor even desmo valves. My 500GTL has neither and it runs great. (ok. bastard child)
Second, they have sort of a religious thing going. I mean about their engine design. If htey changed anything drastic, it might be akin to admitting there is nothing particularly special about a transverse L-twin. I mean, it's special to ME but engineering-wise it is kind of dated.
I am sure there is a few dry sump engines in their design shop. They have dozens of engines on stands for study and experimentation. Probably built a few and then it wouldn't fly past the marketing guys.
^ Unofficial Counterpoint :) :
There definitely was a shitstorm over the 696. But I think the end result has been plenty of sales, albeit to a new breed of owner of the undesirable kind that hands out in NMC ;) But a marketing success for Ducati.
And dry sumps are technically cool. I don't really think there would be any real resistance from purists. And real purists still think belt drives are a sacrilege but they're selling.
I think it's pure economics, rather than resistance from the marketing guys; the bikes seem to be selling OK as is, although I don't have any recent sales numbers, so why change anything major.
let me revive this old thread as i am thinking about this mod now and i have probably the same qualms ducatiz might have had when he started this thread. but i start to arrive to a different result he did. looking at the famous posts he copied in at the start of the thread, i actually do not see any reference to a vacuum. the bcm post talks about hollowing the reed valve out - people do not do that when they do this mod. it also worries about oil build-up above the valve, but how will that damage the engine (as long as you check that your oil level is fine, and maybe clean up the filter or any gunk in the hose - if you put your filter on top of a hose)? the more to-the-point nichols post is a little bit confusing to me. first, no mention of a vacuum there either. (i do not argue that there is no vacuum there, i just argue that it does not have a profound effect on the operation of the valve - i think the vacuum generated by an open airbox fairly far away from the crankcase breather is not even close to the pressure generated inside the engine by possible blow-by gases) second, the sentence "The stock system is less restrictive because there is more volume making it less restrictive." does not make sense to me - how is the volume of the hoses+oil breather box+airbox bigger than the whole atmosphere? later parts of the post talk about race bikes (no vacuum mentioned) and then again about monsters, with the similarly confusing statement "Therefore, the system that allows you the largest volume to pump into is the stock system. This system pumps into the airbox and has the added benefit of a collection/separation tank between the crankcase and the airbox." again, how is the atmosphere smaller than those he mentions? and again, no mention of the vacuum. also, by stating the system "pumps" sort of implies that the crankcase blow-by gas pressure is the more important in opening the valve, not the airbox vacuum.
again, i do not argue that you can have ill side effects - blow-by spitting oil on your leg or on the rear tire for example. but i do not think this mod can damage the engine itself.
also, it might be against the law, but all our exhaust mods are against that as well. and i think the exhaust mods have a worse effect on the environment than this one.
any proof that this mod can damage the engine?
Isn't the advantage to the airbox the fact that the engine is sucking air in, creating an effectively lower pressure than would be the case w/o the airbox?
absolutely, the only question is, how big is that effect compared to the pressure coming from the crankcase. is it big enough so that by removing it, you alter the behavior of the valve so much so that some sort of damage results in the engine?
Quote from: Fergus on December 15, 2010, 10:25:37 AM
Isn't the advantage to the airbox the fact that the engine is sucking air in, creating an effectively lower pressure than would be the case w/o the airbox?
you mean the engine intake are sucking air? if so, yes. the airbox has a vacuum and draws on the crank vent.
Quote from: hunduc on December 15, 2010, 10:34:26 AM
absolutely, the only question is, how big is that effect compared to the pressure coming from the crankcase. is it big enough so that by removing it, you alter the behavior of the valve so much so that some sort of damage results in the engine?
At a BCM maintenance seminar, Bruce Meyers said the difference in power was minimal in a 2 valve motor, I can't imagine there would be any way venting the crankcase to atmosphere could actually cause damage
had mine vent to atmosphere for a half dozen years now it seems. no problems.
would i do it again? probably not. i already did it on this one and it looks good, don't have the parts to go backwards.
on a sbk, hell no i would not do it.
Quote from: a m on December 15, 2010, 12:00:08 PM
would i do it again? probably not.
why not? pls elaborate...
Quote from: Dan on December 15, 2010, 11:29:55 AM
At a BCM maintenance seminar, Bruce Meyers said the difference in power was minimal in a 2 valve motor, I can't imagine there would be any way venting the crankcase to atmosphere could actually cause damage
Yes, the difference is minimal on a 2 valve, but the difference exists. IMO, the individual needs to recognize there is a difference and removing the breather box itself is not a performance enhancement. Then that individual can make an informed decision. Clearly, the power gain from a set of flat slides on short manifolds trumps the power loss of venting to the atmosphere.
I run FCR 41s with an open air box, but I have kept the stock breather system. I only run the pull cable and can fit it with a squeeze around the breather hose into the air box. I like the idea of intake vacuum helping to relieve crankcase pressure. This assistance with reducing parasitic power losses in the engine due to crankcase pressure may be of benefit as I'm running higher compression pistons and porting which will increase both the mechanical and dynamic compression.
If the stock set up gives one extra horsepower then I'm happy.
Quote from: koko64 on December 15, 2010, 03:01:32 PM
I run FCR 41s with an open air box, but I have kept the stock breather system. I only run the pull cable and can fit it with a squeeze around the breather hose into the air box. I like the idea of intake vacuum helping to relieve crankcase pressure. This assistance with reducing parasitic power losses in the engine due to crankcase pressure may be of benefit as I'm running higher compression pistons and porting which will increase both the mechanical and dynamic compression.
If the stock set up gives one extra horsepower then I'm happy.
I've often wondered if there is a way to minimize the system so that it's smaller and tanks up less space. perhaps even used hoses that were form-fit so they snaked around the engine up to the airbox. I think what bothers people about it is the vent-> hose -> box -> hose -> airbox that adds to the complexity of the engine's look.
Quote from: hunduc on December 15, 2010, 12:08:28 PM
why not? pls elaborate...
For the reasons listed just above this post and below yours, primarily. If you think about it, it makes since: Air is in the crankcase, when the pistons travel 'down' they need to be able to move that air out of the way. In the stock venting system, the air box and intake are 'pulling' that air out of the way.
I would imagine that the smaller the displacement and shorter the stroke the less it makes a difference, but i got other things on the mind right now to think too much into it.
i removed mine for clutter reasons. just like the airbox.
for performance i'd leave it on, and not only stick with an airbox, but creatively enlarge mine.
Quote from: a m on December 15, 2010, 04:04:05 PM
but creatively enlarge mine.
heh... that's what she said.
[laugh] [evil] [laugh]
And you could make a bigger carbon air box, and sell some copies to other DMFers ;)
Quote from: ducatiz on December 15, 2010, 03:05:08 PM
I've often wondered if there is a way to minimize the system so that it's smaller and tanks up less space. perhaps even used hoses that were form-fit so they snaked around the engine up to the airbox. I think what bothers people about it is the vent-> hose -> box -> hose -> airbox that adds to the complexity of the engine's look.
Yeah, I had to frig around with the hose to make it work. Mine is the stock hose, shortened a little and runs along the side and above the battery box. Very similar to the stock hose run. I put the FCR cable on and then refitted the hose around it with some cursing. It's not too bad. You could easily get some good hose and fittings from an auto/speed shop and rig something up that looked better and fitted easier.
With a hole saw and some fittings I can't see why some of the more crafty types couldn't rig up a hose to one or both of the larger K&N pods.
A thought; opening the air box will probably reduce the vacuum draw on the crankcase hose anyway. Probably works better on the stock air box. Hope I'm wrong. [bang]
Anyone read anything that addresses this?
Quote from: a m on December 15, 2010, 04:04:05 PM
For the reasons listed just above this post and below yours, primarily. If you think about it, it makes since: Air is in the crankcase, when the pistons travel 'down' they need to be able to move that air out of the way. In the stock venting system, the air box and intake are 'pulling' that air out of the way.
I would imagine that the smaller the displacement and shorter the stroke the less it makes a difference, but i got other things on the mind right now to think too much into it.
i removed mine for clutter reasons. just like the airbox.
for performance i'd leave it on, and not only stick with an airbox, but creatively enlarge mine.
:)
so the only reason you wouldn't do it again is performance, right?
did you feel the drop in performance when you removed the stock system?
i may figure out how to do that eventually. starting with pre-02 frame carbies.
EVR doesn't do it, there's probably a reason. Likely #1 reason, most monster owners aren't really after high dollar more power when its easier to go for a SBK or naked SBK
It would be very interesting to see how one might make a tank/airbox design with different filter position more like the 748-998 superbikes (bottom of tank was lid of airbox)
Quote from: hunduc on December 15, 2010, 04:57:44 PM
:)
so the only reason you wouldn't do it again is performance, right?
did you feel the drop in performance when you removed the stock system?
hell if i know. i did that around the same time i put on some performance goodies (like lightweight flywheel), so there's no way of knowing.
i am concerned about a longterm wheelie dumping out my precious oil on my back tire. less concerned about the oil making me wreck or causing another accident, but that's my damn oil and i'll keep it as long as i care to.
Quote from: koko64 on December 15, 2010, 04:57:22 PM
A thought; opening the air box will probably reduce the vacuum draw on the crankcase hose anyway. Probably works better on the stock air box. Hope I'm wrong. [bang]
Anyone read anything that addresses this?
i think you are right there. i have the dp ecu, hence the open airbox.
Quote from: a m on December 15, 2010, 04:59:56 PM
less concerned about the oil making me wreck or causing another accident, but that's my damn oil and i'll keep it as long as i care to.
:)
that damn oil, trying to escape any way it can.
Quote from: hunduc on December 15, 2010, 05:01:35 PM
i think you are right there. i have the dp ecu, hence the open airbox.
With the open air box, at lower revs there will still be some vacuum and therefore an advantage over venting to the atmosphere. With the open air box, at high revs there will be even more air rushing over the opening of the breather hose creating a greater vacuum draw on the crankcase. So at low revs a little advantage, but at high revs it works well and that's when you need it. That's what I keep telling myself.
Someone may have actually tested this to know for sure.
Thoroughly interesting read from beginning to end [thumbsup]
May throw a little light on my extremely minor crankcase breather oil "leak" (calling it an actual leak is a serious overstatement, its a minor weepage really). I have WASPworks airbox-be-gone PUK fitted to my 09 M1100, meaning that the stock hose connected to the stock crankcase breather is no longer connected to the airbox for the entirely obvious reason. Instead, at the end of the stock hose I have a cute, lil' weiner of a K&N.
So here's the issue: My oil weepage seems to be coming from the join in the crankcase breather itself (I originally thought it was coming from between crankcase and breather). Could it be that - in the absence of any induction induced vacuum - that oil which has got beyond the breather's reed valve rather than being scavenged up into the airbox for future combustion (my understanding is becoming a bit dodgy here) is collecting in the hose above the reed valve, eventually weeping out between the breather's join (at the point where its assembled around the reed valve)? Long winded question there I know, hope it makes some sense ???.
AFAIK there is a small hole next to the valve, so any oil should run back. Probably not all of it and probably with a short delay. Maybe enough to leak out? Anyway, a leak should be fixed, yes?
Quote from: ungeheuer on December 16, 2010, 01:53:28 AM
Thoroughly interesting read from beginning to end [thumbsup]
May throw a little light on my extremely minor crankcase breather oil "leak" (calling it an actual leak is a serious overstatement, its a minor weepage really). I have WASPworks airbox-be-gone PUK fitted to my 09 M1100, meaning that the stock hose connected to the stock crankcase breather is no longer connected to the airbox for the entirely obvious reason. Instead, at the end of the stock hose I have a cute, lil' weiner of a K&N.
So here's the issue: My oil weepage seems to be coming from the join in the crankcase breather itself (I originally thought it was coming from between crankcase and breather). Could it be that - in the absence of any induction induced vacuum - that oil which has got beyond the breather's reed valve rather than being scavenged up into the airbox for future combustion (my understanding is becoming a bit dodgy here) is collecting in the hose above the reed valve, eventually weeping out between the breather's join (at the point where its assembled around the reed valve)? Long winded question there I know, hope it makes some sense ???.
You just have a weepy valve.
Remove it, clean it up, and seal the joint with clear silicone and it will stop.
Quote from: humorless dp on December 16, 2010, 03:51:32 AM
You just have a weepy valve.
Remove it, clean it up, and seal the joint with clear silicone and it will stop.
red silicone will make the bike faster
pretty much stopintime and DP hit the nail on the head. They used to leak all the time - mine was doing a bad job so I replaced it with a nichols one but they seem much better now. If you want to bling it out, you can always get a billet one.
or use red silicone.
The air velocity in the 2V airbox is not that high. If you open up a few holes on the cover, the flow is in the order of less than 16 MPH at 9K RPM. If the airbox velocity is less than air velocity around the bike when it is moving, using it as a source of vacuum may be silly. You may be better off using a venturi with the faster airflow down the sides of the bike.
You must do two things, vent the excess pressure from the crankcase (or your bike will turn into a Triumph, and no offense intended), and not allow any oil to leak into the rear tire. Anything else is gravy, driven by practical considerations.
If you do not want to carry the canister, don't. I have a long hose from the crankcase reed valve to the rear of the bike, capped with a low pressure one way check valve. The check valve allows the positive crankcase pressure to vent to a low pressure area. I don't use a filter, gas flows out. The long hose helps some of the oil vapors to condense and fall back through the drain hole in the reed valve. Haven't checked to see if the hose holds a slight negative during piston rise, but it probably is better than the stock setup. Some superbikes do something similar, gutted the reed from the crankcase and connected the hose to a second one way valve and then that to the airbox.
make the beast with two backs. My bike came to me in pieces, nothing on the damn crank case breather. Not to mention it's setup with pods for FCR41's, there was no airbox included. How the hell do I retain the crank case vent system?
Quote from: 671M900 on December 16, 2010, 07:08:33 AM
make the beast with two backs. My bike came to me in pieces, nothing on the damn crank case breather. Not to mention it's setup with pods for FCR41's, there was no airbox included. How the hell do I retain the crank case vent system?
as soon as you go the pod way i guess the original vent system is out. the oem system vents into the airbox - no airbox, no venting there. it might be possible to rig up some strange system where your blow-by somehow goes back to the air intake (maybe with hoses), but i have never heard anybody doing that for a monster.
you might be able to try to go back to the very original airbox-oil breather box setup by finding them on fleabay...
I don't see the point of pods unless you are using short manifolds. Airbox with a K&N filter + an open top (i.e. Ferracci top) is just as efficient to move air.
pods is fo' looks, certainly not for performance
Quote from: a m on December 16, 2010, 09:26:32 AM
pods is fo' looks, certainly not for performance
necessary for short manifolds. looks? ok.
not necessary!
(http://www.jako-motorsport.de/daten/dienstleistungen/vergaser/image/bild05.jpg)
(http://www.jako-motorsport.de/daten/dienstleistungen/vergaser/image/bild04.jpg)
and from Jako's Super-Due:
(http://www.jako-motorsport.de/daten/motorraeder/sdue/picts_sdue/bild3.jpg)
Quote from: a m on December 16, 2010, 09:57:23 AM
not necessary!
(http://www.jako-motorsport.de/daten/dienstleistungen/vergaser/image/bild05.jpg)
(http://www.jako-motorsport.de/daten/dienstleistungen/vergaser/image/bild04.jpg)
and from Jako's Super-Due:
(http://www.jako-motorsport.de/daten/motorraeder/sdue/picts_sdue/bild3.jpg)
interesting, they made tubes to extend the throat.
on the top two.
the bottom one he molded his own carbon fiber airbox that goes around the split singles and really benefits from still having 'tuned' (length chosen for particular power curves) velocity stacks and a big volume.
Quote from: battlecry on December 16, 2010, 06:41:50 AM
The air velocity in the 2V airbox is not that high. If you open up a few holes on the cover, the flow is in the order of less than 16 MPH at 9K RPM. If the airbox velocity is less than air velocity around the bike when it is moving, using it as a source of vacuum may be silly. You may be better off using a venturi with the faster airflow down the sides of the bike.
You must do two things, vent the excess pressure from the crankcase (or your bike will turn into a Triumph, and no offense intended), and not allow any oil to leak into the rear tire. Anything else is gravy, driven by practical considerations.
If you do not want to carry the canister, don't. I have a long hose from the crankcase reed valve to the rear of the bike, capped with a low pressure one way check valve. The check valve allows the positive crankcase pressure to vent to a low pressure area. I don't use a filter, gas flows out. The long hose helps some of the oil vapors to condense and fall back through the drain hole in the reed valve. Haven't checked to see if the hose holds a slight negative during piston rise, but it probably is better than the stock setup. Some superbikes do something similar, gutted the reed from the crankcase and connected the hose to a second one way valve and then that to the airbox.
Hmmm.. Food for thought. Did you measure this?
So an open air box negates to some extent the vacuum draw on the crankcase?
Is it still worth using the stock breathing system with an open air box, as far as applying vacuum scavenging to the crankcase goes?
What about the system you describe with a hose to the rear of the bike from the stock 'baffle box'?
Quote from: ducatiz on December 16, 2010, 11:34:48 AM
interesting, they made tubes to extend the throat.
You mean the orange velocity stacks in the air box? These are really important and effective for minimizing turbulence in the airflow. Even these relatively short ones can change the airflow drastically. If you look in the stock airbox it has velocity stacks molded in.
As a side note, it's often much better if they have a fat, rounded lip rather than the relatively sharp edge created by just pressing metal into a horn shape. Again, turbulence is greater over the sharper edge.
Scott
Quote from: scott_araujo on December 16, 2010, 01:32:05 PM
You mean the orange velocity stacks in the air box? These are really important and effective for minimizing turbulence in the airflow. Even these relatively short ones can change the airflow drastically. If you look in the stock airbox it has velocity stacks molded in.
As a side note, it's often much better if they have a fat, rounded lip rather than the relatively sharp edge created by just pressing metal into a horn shape. Again, turbulence is greater over the sharper edge.
Scott
No, the adapters from the carburettors to the airbox itself - the u-bend is on the side closest to the airbox so that the carbs can still be on short manifolds to the head.
Quote from: scott_araujo on December 16, 2010, 01:32:05 PM
You mean the orange velocity stacks in the air box? These are really important and effective for minimizing turbulence in the airflow. Even these relatively short ones can change the airflow drastically. If you look in the stock airbox it has velocity stacks molded in.
As a side note, it's often much better if they have a fat, rounded lip rather than the relatively sharp edge created by just pressing metal into a horn shape. Again, turbulence is greater over the sharper edge.
Scott
I have a set of shortened stock rubber stacks from a carbed Monster. I haven't tested them as yet. They have about the same shape and radius as the stockers, but the trumpet sits flush with the base of the air box. The expected advantage is that they sit further from the air filter element and help hold the torque peak for longer, but we will see if the shortened length has any drawbacks with the power curve and turbulence.
I had a look (again) at some of the info from the Nichols site and went over some of the links from threads here.
Came to the conclusion that venting to as large a cavity as possible at less than atmospheric pressure is still the best way to go. The bigger the cavity on the crankcase side of the filter medium protecting it from the atmosphere the better.
Since the air box adds to the overall volume in addition to the breather box/oil separator, this helps to add to the crankcase volume to reduce pumping losses.
Also, even slightly lower than atmospheric pressure in the airbox is of some help.
So three things to consider besides aesthetics, venting to large cavities that extend crankcase volume, having some vacuum assistance to bring cavity pressure to below atmospheric pressure, and venting safely in the event of oil spillage.
I'll stick with the stock system (although the plumbing annoys me).
Just out of interest, I'm looking at page 36 in Ian Falloon's book "Desmoquatro Superbikes".
There is a picture of an 1993 888 Corsa with the body work off. It has a large volume hose from the crankcase breather running to that Corsa style breather cavity that people have mentioned. The cavity is over a foot long. The cavity nearly runs the length of the rear guard under the tail area. It has another hose running back to the air box.
I don't know if the factory was using full ram air by then or fresh air to an open airbox.
OK so lightly skimming the entirety of this thread, I'm left with the understanding that removing the breather box is a detrimental endeavour. A diminished return.
I've been playing with the idea of buying a Hypermotard for a couple of years now. I love those bikes, fun fun fun. However the big problem with the HMs is the fuel capacity. ~90 miles a fillup, bad bad bad. I'm the type of person who would be out having fun fun fun then run out of gas because motorcycles don't tend to have fuel guages, just low fuel warning lights. Keeping an eye on the trip odo is easier said than done, and inaccurate when you're out doing wheelies and other hooning activities out in the middle of nowhere. Since I like to ride out in the sticks to stay away from grosse traffique this could end up in a situation where I'd have to push the bike which would not be a happy day. Just like doing everything I can to avoid crashing, I'd like to also do everything I can to avoid being stuck on the side of the road. Some say it's an inevitable side effect of riding, I say screw that I don't ever want it to happen to me.
There seems to be a solution - the CA Cycleworks Hi-Cap fuel tank. Chris is quite a crafty problem solver. But this requires going to pod filters in lieu of the stock airbox and deleting the breather box as well to provide the space for the high capacity fuel cell.
So what now? Carry a jerrycan on the back of the Hyper?
i'm still not sure how detrimental it is. what, you lose a couple horses? i doubt we ride our bikes to the limit - not even close. if you are worried about spitting oil on the back wheel, just move the filter higher or to the side. so many people did this mod, and we have a couple who don't like it.
what's wrong with a jerrycan, btw? or maybe you could use those backpacks which are for hydration for cyclists, just put gas in it. :)
I reckon you should consider the TPO kit as it has velocity stacks in the pods, and run them under Chris' tank. I hope they fit because that's what I would do. The most important thing is to have a well designed velocity stack/trumpet inside the filter whether it be a pod or panel filter in an airbox.
There is also the issue of whether you could run a well designed velocity stack within a cut down air box. No harm enquiring with TPO. If the airbox has to be removed completely for a bigger gas tank then run pods. It's all about compromise. It's what gives the best net performance gain on a practical street bike. I've seen the film "Deliverance" and I wouldn't want to run out of gas in the middle of nowhere! :o
I'm guessing that you would gain more from that set up than you would lose from venting the crankcase to the atmosphere. With the right fueling you might gain 5-10hp from the TPO Beast set up and lose one from the crankcase set up. You are still ahead by a mile. The main thing is to not get oil on your back tyre or have engine leaks. I would still run the vacuum hose to an oil separator box or racing style catch tank to add to crankcase volume and protect your rear tyre from oil when you wheelie. It wouldn't be connected to an airbox but it would vent to the atmosphere via another cavity.
I only run the airbox because that 1 hp is important to me as I don't have many to spare! Come to think of it I'm going to do a dyno run with and without the crankcase hose connected to the airbox to see exactly how much difference it makes.
I am in the process of organising a dyno test for a carbed M900 which compares pods to airbox, and airbox with short rubber stacks verses stock rubber stacks. When I test the pods I will of course run the crankcase breather from the cavity under the seat to the atmosphere. I will still have the extra volume of the oil separator box cavity.
If pods or airbox give better performance then I will convert my bike and my friend's bikes to the 'winning' set up. Then I will do the same for customer bikes once I know the truth. The testing I am going to do relates more specifically to carbed bikes so I look forward to seeing what you choose to do and how it works. For my money Ungehuer is running WASP velocity stacks and pods with modified fuelling and his bike sounds like it is very, very strong. Hopefully we will test it also. I think the TPO set up is similar and if I had an 1100 or 1000DS I would try it.
pods dont hurt if you have a velocity stack. If properly sized, its almost unnoticeable.
You know, during some recent mental ruminations I did consider getting hold of some old style carb SS oil separator cavities and put them behind the Monster left side cover...
I thought about running a hose from the stock oil separator box and looping it back to extra cavities to give more volume again and eliminate the hose to the airbox. Maybe the extra volume would mitigate any losses from not running the hose to the airbox vacuum.
If you have to eliminate the stock oil separator cavity then fit a substitute from another model that might fit in some odd space. Then run that cavity to the atmosphere. It will at least catch some goop and restore some crankcase volume to the breather system. There may be some trick alloy or carbon race style ones around that look the part. Since space is at a premium on a HM this could be a solution.
Running a breather filter directly on a HM crankcase breather valve is tricky because how can you not wheelie all the time on a HM? [evil]
I'm going to try the TPO kit with filter covers and run the crank-case vent line up to the mid tank. I'll post my findings once my tech has it all tuned up.
Quote from: scduc on January 30, 2011, 02:45:58 PM
I'm going to try the TPO kit with filter covers and run the crank-case vent line up to the mid tank. I'll post my findings once my tech has it all tuned up.
very interested in the result (especially because we have the same bike)... keep us posted pls.
Ok guys, I'm gonna dyno test pods with breather to the world Vs open air box with breather to the air box. I'll do another thread for that.
I have tested the breather hose with the open air box both connected and disconnected and couldn't see any difference, but my bike was not flat out racing, just diagnostic power runs up to 8500-9000 max (held open enough to test but not too much for the old girl). I found no difference that I could be sure of attributing to the crankcase breather system. But my bike isn't a high revving desmoquattro under racing conditions.
I'm gonna leave the oil seperator box under the seat and put a little filter over it or some filter foam cable tied on, or not. I think having a flash looking filter on the end of the breather is a little risky, but if you put it on the oil seperator box at least oil wont puke onto your wheel. You will also have some 'fake' crankcase volume added to relieve some pressure.
I'm giving notice of the test as a courtesy as this has been a very interesting thread. There is also self interest as I also need some advice regarding the crankcase breather aspect.
If the pods have the same power I will keep them (given some jetting as they have 30% more filter area, but 'flow from the side'), if not I will go back to the open air box.
I will consider running the vacuum hose to the front of one or both of the pods and test that. I'm guessing that this will give a more direct vacuum to the crankcase, but I could be wrong. I am also considering buying another seperator box and placing it behind the steering head where the bottom of the air box was, and running the crankcase hose to it for extra volume and maybe also to the pods.
Even if I choose to not use the vacuum set up I am interested in providing plenty of virtual crankcase volume with a second oil seperator or breather cavity as I will have the room. I better try that before using the hole saw on the front of a pod and finding it made no difference! [bang]
If the open air box negates some of the vacuum scavenging effects of a 'closed' or ram air airbox then the extra volume method looks promising. I could run a cool looking filter from that.
I have been spending some dyno money as an educational process. I tend to theorize alot over a few beers but I have committed to some practical testing. Testing various concepts and how they interact is important to me so it's been worth it. All the 'experts' I have consulted have said that I should learn by just doin' it, as there is no accessable course for me down here. I may have to go to the States for a course/holiday.
If anyone has any advice it would be appreciated before I embark on another reckless adventure!
Cheers
sounds like a much needed experiment, so kudos for undertaking it. up to this point we only had anecdotal evidence (both for and against of course...). i eliminated the oil breather this spring, and i did not notice any difference. but i never ride my bike even close to its limit.
no useful suggestions from here, just curious about the results. keep us posted, and good luck with it.
Ok, I'll start by saying I havent read all 10 pages of this thread. But I got the general gist.
I dont really understand what the big hubbub is. For the sake of making this simple lets just focus on the duc twin motor.
1) For one piston moving up in a duc motor (into the head), there is one moving in the opposite direction. So the change in displacement on the crank side is effectively balanced. Ok so maybe the pistons dont seal equally but in theory if they were both perfectly sealed, all should balance out.
2) Now lets assume that the crank is not perfectly sealed and that some of the compressed slug of air leaks past the piston. So now you have a positive differential on the crank side. There are two locations where the positive pressure can leak to. Thru the other piston or thru the breather. Like in nature. The release is mostly going to be from the easiest source. The breather valve.
Personally I couldnt care less up HP values. If I did I wouldnt have bought a 2V air cooled motor. But I think this would have to be quantified by a dyno. I have no idea which way the results would go.
But to say that seals can prematurely fail from excess overpressurization is a wee bit extreme. I could see premature failure happening on an improperly tuned motor with engine compression way off spec. If you run a compression test and both are within spec, I dont think you're going to have any issues on way or another.
That being said, even if you had a breather hose connected to your airbox, an out of spec piston with bad compression could still result in premature failure of the seals. Just like a k&n setup.
So comparing apples to apples I dont think you will see a problem either way.
Quote from: EEL on July 02, 2011, 11:00:38 AM
Ok, I'll start by saying I havent read all 10 pages of this thread. But I got the general gist.
I dont really understand what the big hubbub is. For the sake of making this simple lets just focus on the duc twin motor.
1) For one piston moving up in a duc motor (into the head), there is one moving in the opposite direction. So the change in displacement on the crank side is effectively balanced. Ok so maybe the pistons dont seal equally but in theory if they were both perfectly sealed, all should balance out.
2) Now lets assume that the crank is not perfectly sealed and that some of the compressed slug of air leaks past the piston. So now you have a positive differential on the crank side. There are two locations where the positive pressure can leak to. Thru the other piston or thru the breather. Like in nature. The release is mostly going to be from the easiest source. The breather valve.
Personally I couldnt care less up HP values. If I did I wouldnt have bought a 2V air cooled motor. But I think this would have to be quantified by a dyno. I have no idea which way the results would go.
But to say that seals can prematurely fail from excess overpressurization is a wee bit extreme. I could see premature failure happening on an improperly tuned motor with engine compression way off spec. If you run a compression test and both are within spec, I dont think you're going to have any issues on way or another.
That being said, even if you had a breather hose connected to your airbox, an out of spec piston with bad compression could still result in premature failure of the seals. Just like a k&n setup.
The question is how much pressure is built up in the case and how much ventilation (or vacuum) is present to account for it?
The easy solution is to put a pressure gage on the case vent.
From my experience (which is limited to forgetting to put the oil fill cap back on) there is plenty of pressure generated in the case WITH the breather/vacuum system still in place on the airbox. I know this because when I leave the cap off, oil sprays out like crazy and it's due to pressure, not moving parts at that location.
Removing the vacuum part of the equation would make that even higher. How much? I don't know.
next thing we'll see is koko64 doing a miniature EGR setup too... :P
Quote from: ducatiz on July 02, 2011, 11:31:26 AM
The question is how much pressure is built up in the case and how much ventilation (or vacuum) is present to account for it?
The easy solution is to put a pressure gage on the case vent.
From my experience (which is limited to forgetting to put the oil fill cap back on) there is plenty of pressure generated in the case WITH the breather/vacuum system still in place on the airbox. I know this because when I leave the cap off, oil sprays out like crazy and it's due to pressure, not moving parts at that location.
Removing the vacuum part of the equation would make that even higher. How much? I don't know.
If you just think it though, you can surmise that its not a whole lot of vacuum. The same principle that applies to the breather applies to the airbox.
Its like sucking thru a straw, no matter how powerful you suck you can only get so much pull. The rest is just wasted effort. Since the breather hose is directly connected to the airbox. There is an effective short circuit in the static vacuum developed in the breather line because of the gigantic hole present in the airbox to bring in air. Its a trade off. You get more airflow in the box for lower static vacuum.
I hope someone does measure so we can all see that its going to be negligible
If you want more substantial vacuum, make the airbox fresh air intake SMALLER.
The stock airbox intake is tiny. my 05 monster had a nozzle that was about 3 x 0,5 inches.
Quote from: j v on July 02, 2011, 11:41:15 AM
next thing we'll see is koko64 doing a miniature EGR setup too... :P
I got the little K&N A/F ratio meter. As they say great minds...
Quote from: ducatiz on July 02, 2011, 04:43:28 PM
The stock airbox intake is tiny. my 05 monster had a nozzle that was about 3 x 0,5 inches.
Well at least there is a well documented performance trade off in that case, open up that air box! [laugh] I bet you did.
The resonance and air flow issues win over the crankcase vacuum issue. Certainly with the carbed bikes.
I may well purchase another oil separator box and put it up front to satisfy the crankcase volume principle if I can't stomach taking the hole saw to the front of the pod. [puke] A trick carbon one would look cool and give the impression i know what I'm doing! Picture it over a few beers with the boys, "Yeah, that's for increased crankcase volume, trick". [laugh]
It's about competing principles and theories isn't it? I mean I know tuners who will do anything to keep the intake charge pure and will plumb the breather hose to an exhaust pipe to use vacuum assistance. The drag racers claim significanthorse power increases doing this but to vent to the intake charge is anathema to them. They would rather use a separate pump.
My EGA readings at idle went up by 0.4-0.5 with the breather hose attached to the air box. Even with a leaner idle mixture setting via the IMS and Slow Air Jet Screw my richest A/F ratio at idle was with the crankcase breather attached. I wasn't expecting that. I have had good leakdown tests by the way.. 175-180 psi cylinder pressure.
Although it would seem obvious I wasn't really expecting that result.
But first I will see if pods rob power. They may just be a
less inefficient air flow system than the compromised standard air box. A correct air box ala Jako might just give the best of both worlds.
Now try a dyno run with and without the reed valves in the crank vent. I'd really like to know if there is a difference there.
Isn't that the race set up that has been mentioned?
I mean with no reed valve venting into a huge breather/oil seperator box and then back to the air box via a auto type one way valve? The breather box gives the extra volume and often sits in the tail section.
That link explained it well, the Corsa set up.
One question, if the reed valve is doing it's job, why do we need a filter if venting to the atmosphere? Chris Kelley has mentioned just leaving the oil seperator nozzle bare. A mate of mine has a little K&N filter on it as some do.
Another question is, why provide breather cavities for extra crankcase volume when you can vent to the world?
Quote from: koko64 on July 02, 2011, 06:32:01 PM
Another question is, why provide breather cavities for extra crankcase volume when you can vent to the world?
i've always understood those boxes were meant to catch oil. sort of a centrifugal nautilus design.. like the old VW oil bath air filters -- the oil never gets sucked into the vacuum because it has to go past several right angles, against gravity.
I suppose it's all a balance between competing tuning principles.
Keeping the intake charge clean Vs vacuum assist to crankcase breathing.
Strong air box vacuum Vs open air box and maximum air flow.
Resonance mangement Vs Strong air box vacuum.
Creating crankcase volume Vs constraints with space.
Crankcase venting and pumping losses Vs emissions and noise laws (if you care).
Etc, etc.
Given the constraints of the long manifold carb motor and it's compromised air box, the above issues have to be dealt with in terms of their tuning potential.
The testing I am doing is to prioritise the tuning effort.
Any advice that could save me dyno time$$ is welcome.
Quote from: ducatiz on July 02, 2011, 06:58:54 PM
i've always understood those boxes were meant to catch oil. sort of a centrifugal nautilus design.. like the old VW oil bath air filters -- the oil never gets sucked into the vacuum because it has to go past several right angles, against gravity.
Very true, but they are also cavities that provide for
virtual crankcase volume increases. This includes things like the Corsa breather box, the air box and oil seperators. They all add up to increased crankcase volume. What I have trouble understanding is if you can get away without vacuum assistance then why not vent to the atmosphere? I know some racing regulations stipulate enclosed breathing systems for safety in case of of an oil puke (like EPA), but some race tuners vent to the atmosphere but with an oil catch bottle.
Maybe it's the V-twin's pumping losses compared to the inline four, apples and oranges.
Quote from: koko64 on July 02, 2011, 06:32:01 PM
Isn't that the race set up that has been mentioned?
I mean with no reed valve venting into a huge breather/oil seperator box and then back to the air box via a auto type one way valve? The breather box gives the extra volume and often sits in the tail section.
That link explained it well, the Corsa set up.
The race setup does have a remote reed valve when the full system is used. I have seen a few use the race breather without the remote reed, not the complete system, which I suspect reduces power.
Thanks guys for going over this with me after the mother of all threads.I appreciate the responses.
I have only seen pictures of the Corsa system, I've only eyeballed in line four race set ups. That would be cool to run on anything big bore or racing I reckon. Could probably run it on a Superlight. I'll probably rig something up near the steering head under the pods on the Monster if I don't get lazy and slap a mini K&N on the oil seperator box.
Just couldn't find a loss on the dyno with the breather hose detached from the air box with the stock set up. Wasn't racing though or holding it flat out for too long, just enough for the EGA to clear the accelerator pump.
Just 'guestimating'; little filter on the breather probably a power loss and oil leak/crash risk, seperator box to atmosphere or air box not much difference. I'm saying that the Monster system is a very poor man's copy of the Corsa system and don't do much due to constraints on packaging. Small oil seperator box, whimpy air box, reed valve for emissions more than power. It's beter than nothing and keeps the EPA happy though.
Does that ring true to you?
(Kind of thing to discuss over a few beers, but I'm across the Pacific).
I've read about 50% of the pages.
For the system with the tube going into the airbox, especially a pressurized airbox, I think it would not help the system and may even hurt at speed. No test on a Dyno would show this.
If the crankcase is pushing 3 bar and the airbox is pressurized say to 4 bar, there would be no venting and in fact it would stop venting thereby increasing pressure in the crankcase.
the old TT bikes had a box under the seat with the crankcase venting to that where the oil and air were separated and then vented to the air. which would allow the positive pressure of the crankcase to self regulate.
I would suspect even with the stock Monster airboxes there is some pressurization going on at speed to keep up wiht the increased demand of the motor at higher RPM. again no way for test equipment on a dyno to show this.
Thanks Raux, food for thought.
The system you described is what I will try with the pods. Adding further volume is something I will consider with an extra breather cavity. I will try to use the largest filter I can fit off the oil seperator, to minimise any restriction.
Air box resonance or pressurization affecting crankcase breathing is something I want to avoid. I suppose thats unlikely with pods.
I like the idea of keeping the intake charge pure.
Quote from: koko64 on July 02, 2011, 10:31:12 PM
I'm saying that the Monster system is a very poor man's copy of the Corsa system and don't do much due to constraints on packaging. Small oil seperator box, whimpy air box, reed valve for emissions more than power. It's beter than nothing and keeps the EPA happy though.
Does that ring true to you?
(Kind of thing to discuss over a few beers, but I'm across the Pacific).
I agree that the system is a poor-copy of the Corse system, but you have it a little twisted. The reed valve is in the Corse setup - doesn't that mean it is more for power than emissions? The hose to the airbox is not on the Corse system - and you have proven it does not change horsepower - that kind of indicates it is an emissions thing for a Duc motor. A dyno without the reeds would tell the tale.
The Corsa system goes like:
From Crankcase to Box:
Crankase 'breather' (no valve) - hose - underseat breather box.
From Box to Airbox:
Underseat breather box - hose - airbox.... with valve...
That's what I understood j v.
Just been looking at Ian Falloon's desmoquatro book and you can see the hoses to the breather box and back to the air box on the '93 888 Corsa. On the 888 and 996 Corsa bikes you can see just how substantial the breather boxes are. A lot of volume there.
Also been looking at Neil Spaldings book Moto GP Technology, a picture of the WCM bike shows a hose going to breather cavity (cylindrical tank) in the tail, but a hose out the back of the cavity to the big wide world! :D
Yep, that's the setup on the 748RS and the rest. The size of the undertail breather box varied with the subframe/computer model and whether it was a race-only model (RS) or a street version with DP setup. The difference, as I understand it, is achieved from moving the valve to after the breather box, by the airbox, thereby increasing the available crankcase volume itself. The crankcase volume is not increased by anything after the valve, so on the stock setup with the valve inside the crankcase breather, there's no additional volume gained from the breather box, it serves only as an oil collector tank where the oil can then slowly drain back into the motor at the crankcase breather.
Thanks j v.
That is illuminating indeed and settles things in my mind. The most important information so far..
The valve location changes everything. It of course explains the valve location on the race bikes.
I take it's therefore only worth adding extra cavity volume if I'm going to move the valve to the end of the system.
I can remove the reed valve and bung a race type valve in a hose after the seperator box? That effectively adds crankcase volume without adding an extra cavity by shuffling the order of components. It utilizes the existing cavity.
After seeing the WCM system I'm feeling better about not venting to the air box. Real old school. The real reason they got disqualified [laugh]!
Cheers
Post a picture of that one if you can.
if you were going to fab up your own - using the existing two front tabs where the fusebox attaches, and the aft two holes by the tail light / seat latch, you'd want to go "in" at the bottom of your box closest to the engine, and 'out' (to the airbox or otherwise) at the aft section, at the 'face'.
Here's the "BIG" volume underseat breather box for the 748-916-996-998:
(https://lh4.googleusercontent.com/-Njp1KC-CiJo/ThEFcvHM1dI/AAAAAAAAHX0/16buEIVuLw0/s800/IMG_2443.jpeg)
And what I am trying to describe in action on an 888 Corse:
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008032.jpg)
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008027.jpg)
(http://)
(//)
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008020.jpg)
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008019.jpg)
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008018.jpg)
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008033.jpg)
(http://i217.photobucket.com/albums/cc90/jerryxt/888%20corse/02022008015.jpg)
And there's always the hall-of-wisdom article you might gleam some nuggets of wisdom from: http://www.ducati.ms/forums/80-hall-wisdom/36038-crankcase-ventilation-system.html (http://www.ducati.ms/forums/80-hall-wisdom/36038-crankcase-ventilation-system.html)
The one Oronero is selling through his blog looks like this:
(http://2.bp.blogspot.com/_XRaYCz6dULI/TSkR4_wv7aI/AAAAAAAAADI/Wc337WDTFas/s1600/P1010078.JPG)
Some classy carbon cavities there.
Nice to see some close ups of what I've seen in books.
A major fail on transfering the photo of a photo to my computer. The best I can do is text it to you straight from the phone. PM me if that's cool.
The hose out of the back of the WCM bikes breather tank looks like it was purchased from the local hardware store. I love it coz it looks like something I would do. ;)
My understanding is you want to remote the valve to the DP box and put a filter on the outlet so you don't pressurize it. (some bikes having a pressurized airbox)
(http://i219.photobucket.com/albums/cc190/stankbone/du25.jpg)
This may be off topic, but I was sceptical after reading the first couple of pages on this topic ( even though I posted on page 9). I went ahead and did the whole plumbing removal and installed pod filters and the crankcase breather. I personally think the bike has never ran better. My only issue is when its cold, it revs low and I have to give the throttle a little blip at every stop. This is due to the stepper motor. I dont wheelie so I'm not expecting the oil spewing to the rear wheel. I really cant tell if there is power loss, but the weight savings and the clean look out-weights the possible -1hp. I ran my 750 with the crankcase breather fot 10k miles and never had oil come out of the filter. It also appears that many of you are looking to get the absolute most out of the engine as possible. That case I suppose the pressure boxes will play an important role. For the street, I really don't see it as a big deal.
While I "perceive" that mine runs well w/out the system, a goal for removing mine was the same as for removing the EGR system from my truck: only clean air is going in, no oily mist from the crankcase, nor bits of carbon build up from the exhaust emissions. If that comes w a slight adverse effect on performance, it is outweighed by cleanliness and related long-term performance/longevity. (mostly referring to the automobile EGR setup, but in a small way, I think the same is true for carbs + crankcase vacuum)
Quote from: j v on July 04, 2011, 10:49:27 AM
While I "perceive" that mine runs well w/out the system, a goal for removing mine was the same as for removing the EGR system from my truck: only clean air is going in, no oily mist from the crankcase, nor bits of carbon build up from the exhaust emissions. If that comes w a slight adverse effect on performance, it is outweighed by cleanliness and related long-term performance/longevity. (mostly referring to the automobile EGR setup, but in a small way, I think the same is true for carbs + crankcase vacuum)
During recent dyno tests I saw the EGA readings go up at idle by 0.4-0.5 leaner when the breather hose was detached from the air box (and blocked off of course). DP wasn't surprised by this and I suppose I shouldn't have been, but it bears out what you are saying. I had to richen things up with clean air going in! Just illustrates the effect of that oil mist on the A/F ratio. I agree it's better to keep things clean after seeing that.
Since this thread is so long, I have not read all of it, but I found the discussion at the beginning concerning crankcase vacuum (or not) quite interesting.
Many years ago (unfortunately …), I had a Yam XS650 / 860 twin (capacity increase by use of bevel-900 SS pistons and liners, by the way) where I had some problems with the crankcase ventilation. In the end I had a setup consisting of an approx 25 mm hose from the oil filler hole, in-line Ducati reed-valve stopping backflow into the engine as the (parallell)twin pistons rose together, potentially pumping 860 cc of air into the crankcases each revoulution, and an approx 20 mm hose leading into a catch bottle. This catch bottle was then vented to the atmosphere.
The hose leading into the bottle ended just above the bottom of the bottle, with the intention of keeping inflow into the bottle as far away from the vent opening at the top as possible. After a few 100 km some oil would collect in the bottle, eventually submerging the end of the hose coming from the crankcase.
With this setup, I noted that after the engine was stopped, oil would slowly get sucked back up into the crankcase vent hose, rising maybe 20mm to 30 mm above the bottle oil level, and staying there quite long before sinking back.
My conclusion was that the venting was good enough to get any blowby as well as the 860cc geometrical compression in the crankcase on the piston downstroke out of the crankcase, and the reed-valve set-up was tight enough to allow the pistons to draw a slight vacuum in the cases on the upstroke, resulting in a sub-atmospheric pressure in the cases.
Of course, it's not below athmospheric all the time, if it were no oil would have ended up in the catch bottle, but it's my belief that with a set-up like this, and possibly due to the parallell-twin layout, you can have crankcase pressures that are below athmospheric during part of the working cycle.
I suppose maybe the engine is most likely to stop with the pistons shortly before TDC on the upstroke, this beeing the most likely position to create a slight vacuum in the cases to suck oil back up the vent hose.
Building a motor like that is a good test bed for the theory. Very interesting.
Cheers.
start watching at 1:24
The new Ducati Superquadro engine / Il nuovo motore Ducati Superquadro (subtitled) (http://www.youtube.com/watch?v=H7SKvsW_0qo#)
Do you think it is a small version of the vacuum pump used on drag racers, or at least similar in concept?
Quote from: koko64 on October 10, 2011, 04:18:48 PM
Do you think it is a small version of the vacuum pump used on drag racers, or at least similar in concept?
that's pretty much what he says.. i'll be interested to see it in the parts manual when its published --- God knows I can't buy a new bike right now lol
Spose those massively oversquare bores are allowing such high revs, pumping losses have become a real issue. No surprise as the bore to stroke ratio sets a record for a twin.
I hope the gear cam drive makes it to the rest of the models.