Crankcase vent vacuum setup removal = bad

[ducatiz]

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.

[DJ]

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.

[ducatiz]

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.

[mitt]

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

[ducatiz]

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.

[spinned]

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?

[Sgt_H]

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.

[ducatiz]

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.

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.

[Howie]

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?

[Bill in OKC]

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.

[spinned]

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....

[ducatiz]

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.

[Bill in OKC]

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

[A.duc.H.duc.]

   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

[MendoDave]

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.