The dyno I regularly use has changed from a fair to middling dyno to a stingier dyno as far as readouts from local dynos are concerned. After conversations with my dyno guy it appears that upgrades to the same dyno (software, etc) have made his dyno read more conservatively. He is a good guy and we talk about stuff. It got me thinking.
I was aware of different makes of dynos reading differently, Dynojet Vs Factory Pro being very clear examples, and also aware of different models from the same dyno manufacturer reading differently over the years, but what threw me was the same actual dyno reading differently due to programme upgrades. Now my old data is useless. I'm not the only person to have mentioned this after discussion with different people. It seems the later version Dynojet model dynos read more conservative (up to over 10%), and that's leaving out any dyno shenanigans (another issue again). On that note it seems that if you own the whole set up you may be able to play with temp, barometric and correction factors to pump things up to look good. One guy I know who leases the dyno computer is locked out of those parameters and couldn't cheat if he wanted to. His customers have complained of his dyno stealing hp! [laugh]
The dyno I have taken bikes to for years has become more conservative so now I can go anywhere as corrected comparisons are now useless. Shame. The only comparison I can rely on now are the before and after readouts on the same day.
Some guys own the whole set up, some lease the whole set up and some might own the machine and lease the computer hardware. With that comes upgrades to software and firmware that could recalibrate the same machine to read differently. Bugger.
I now have easy access to three dynos and I know for sure they read differently. One is a Dynojet that is owned outright and reads much higher than most around here, one is part owned and part leased that was a midrange dyno among the local ones here but which has recently become stingy, and one is owned outright that is a custom built amalgam of different dynos to meet the operator's particular requirements (brilliant professor type guy in the hills). None of these guys would cheat as they are good blokes, just the machines say it different. One bloke had customers complaining that their bike made less hp than before when run on another dyno, but he was able to point to the big hp increase between his dyno runs after the work. It's just that the improved power after the work was done was still less than the dyno reading from the other side of town!
I am interested in any thoughts from experienced dyno users on this topic.
For those of you that get their bikes dyno tuned, I believe this is the best way if you have access to an accomplished dyno tuner (in conjunction with road testing). Don't feel sad if your bike makes 10hp less than your mate's identical bike with the same mods if it's on a different dyno. Even if the dyno is the same model by the same manufacturer, that means nothing. Just look at the before and after graphs and ignore the hp numbers.
I road tested a bike recently after a dyno tune and took it straight back to have some adjustments made. The configuration of the motor (big air cooled single) had different fuel requirements above what which was theoretically required for a water cooled in line 4 cylinder.While dynos are great tools, that's just what they are and not the whole picture.
Good to know I can easily add ten ponies via choice of dyno. ;D
Not an experienced user yet, but this is the main reason I ended up rolling my own (of yet to be determined consistency)... In the end the house numbers are basically bragging rights. What's really important is percent change and maximizing that result.
I'll know more as I gain experience with the homebuilt job.
You did a pretty cool job too [thumbsup].
Thanks for the kudos... Now I just have to figure the data to log and how to do it.
Lots of racers install o2 sensors for running and remove them for the salt... I'm thinking that plus a single cylinder egt will tell me something useful.
@koko
Are all of the dynos 'inertia' style?
DD. What you are doing is interesting for sure and understandable because you have requirements related to your particular goals. I just it's so cool how you did it :D.
A bloke I know built his dyno out of a few different types available to get what he wanted. It seemed he was able to get features from each dyno manufacturer to meet his own very strict requirements. He tunes everything from modern superbikes to Formula One side cars to old classic and vintage racers.
SD.
I'm told two are the same Dynojet models but with a big hp variance, might be generations of computer software as one is owned outright (reads high around here) and one is leased with periodic updates (becoming more conservative over time). The third custom one does everything. The guy wants to measure everything everywhere in every way. It probably has a Flux Capacitor.
PM sent.
Dynos are best used to compare before and after runs and used for diagnoses /setup. What they truly get used for is bragging rights and bench racing. I have seen people lose their minds trying to chase a silly number that made little to no difference but .... because it was there.
I have used a number of dynos all Dynojets, mine is a 100 converted to 150 spec running winpep-8. The 250i we had at the dealership was great with the eddycurrent brake, I do want that upgrade but for now mine does the job just fine. The one we had prior to that was a 150 , similar to what I have now but both at the dealership were running winpep-7. The winpap-7 dynos have a single pickup on the drum where the winpep-8 has about 12 pickups so the resolution is better. This helps with diagnosing issues some times as little things show up more.
I can tell you they all were off a little between then our first one at the dealership we had to measure humidity and enter all data before running ourselves. #2 did that for us and being brand new at the time the HP was just a little higher than #1. #2 being used also had worn knurling on the drum which allowed some tire slip, strapping the bike down did help equalize this. My Dyno #3 is obviously old and the knurling is good but not new, most bikes do not need to be strapped down but high HP bikes I do tie down. Your dyno that has lost power may simply be losing traction on the drum.
My Dyno is about 5hp lower than the dealership dynos I used, again as long as you are comparing before and after it is no big deal but I have to caution customers about dynos so they are not too disappointed when they see the numbers. I am not sure but have a hunch that winpep-8 lowered the numbers to be more in line with other brands because of the claim of "dynojet-dyno numbers". It may be more accurate but customers still read magazines and sales brochures with bogus hp numbers (engine vs rear wheel hp and dry weights are about as useful), and expect to see advertised numbers because they are sure that their buddys bike is faster.
Can you manipulate the hp numbers? yes by choosing different conversion factors you can fish for the highest number but this is no good if you are comparing your run in DIN and your buddys in SAE one will have a advantage but the bikes are no different. If you are using a DYNO room and the room is pressurized so the room does not run out of oxygen then you are also pressurising the intake charge of the bike and just like any forced induction system they tend to make more HP. A dyno in a small room with no reserve of oxygen will use up whats there and after too many runs the power starts to suffer.
Appreciate you chipping in. Seems Instruments can be used for diagnosis and measurement Vs marketing and propaganda, and like any tools can wear or change calibration. ;D. Cheers.
Over the last few weeks I have had interesting conversations with three blokes who operate or use dynos and build/tune race engines. All three said it wasn't worth using the dyno correction factors anymore, as they no longer believed that one can compare data over time by using them. All agreed that all that mattered were the before and after runs on the same day, and that one should just ignore the actual hp/torque (except the AFR) numbers and look at the curves. Each bloke just ran the dyno uncorrected and accepted that the power displayed was for that day.
When discussing how the local dynos varied so much in their power readings, one bloke said that one dyno known to him displays so much horsepower that there's a hayshed behind the dyno room [laugh].
I can understand where they're coming from, for sure.
Buuuuut......
How would they then realistically compare before/after engine mods that can't be done in one day?
I have no idea mate. A big job might take days or weeks. :-\
I guess they would have to make do.
I also see where they are coming from but like nick said pick a correction factor and stay with it. In the US SAE is the most common so I use it, In Au I am not sure what you use commonly but I am sure there is a standard.
It may also be in their benefit to use whatever the others do not because then they can point to that as the reason the powers "off" make everything apples to oranges and it is some times easier than educating your customers.
They have no choice on long running jobs I'm sure. One guy is getting complaints about his stingy dyno. ;)
I see SAE, PS and STD used , both corrected and uncorrected on Dynojet dynos here.
I 'd be ecstatic just to have my own, but would probably be bankrupt by now from testing every question I've ever wondered about.
Once you buy one you will need to have one after that because it becomes one of the most valuable tools you will own and I do not mean for handing out runs and making money. I have used mine for everything for injection and carb set up to test riding race bikes or non road legal bikes. Diagnosing running issues from final drive to ignition systems.
Yes you will waste tons of time using the BS detector to come to your own conclusions instead of trusting manufacturers specs or some jerk on the internet who is making claims.
I will at some point have a inexpensive modernized dynojet for sale if you feel the need, I think that shipping would kill you but I would consider selling only to buy a eddy current model. Keep an eye open in your are as they can pop up and I would have tried any brand model to start. Keep in mind the spending does not stop after buying as I have spent 3x the money spent buying the dyno on upgrading.
Yeah, thats what JD Hord calls dynos,.. "bullshit meters".
Worked out what has been going on locally. I can compare dyno data from my most used dyno shop back about three years, but after that there is about a 10% difference. So there are two "eras" so to speak with this dyno where the data is comparable with 10% lower, more conservative readings starting around three years ago. It helps me make better sense of long term data.
Any chance it is a dynojet and they switched to winpep-8 software?
I think thats the case. The computers and software, etc are leased and would get upgrades while he owns the dyno. In your experience could that account for a dyno going from "fair to middling among local dynos to stingy" as the owner put it?
When I bought my Dino it came with winpep-7, It was missing a computer to run so I updated it to winpep-8 as it waas the latest and greatest. Comparing the runs now to what I used to get on two different Dynos (dynojet 100 and 250i) at the dealership I used to work at, I am about 10% lower as well. The new software is much higher resolution but I also believe they worked to get "more real world numbers" not "Dynojet dyno" numbers.
In the end it is not a difference in the bikes just correction factors, I just compare before and after runs ad know there is about 10% difference to a older dynojet number. Now I am closer to the factory dyno numbers which they always claimed to be true hp [roll].
On our old dyno my 750 was close to 65 now high 50's
900's low 70's now was mid 70's before.
1000/1100 low 80's
800's mid to high 60's
620's mid to high 50's
Thanks heaps. That helps a great deal and explains a lot. It gives a reference point between the old and new numbers that will help me make sense of the dyno data over the years.
My 900 dyno'd exactly the same on the 'new' dyno with flatslides as it had on the 'old' one with stock carbs.
Right at 75hp.
Not that it truly matters I was tempted to dyno a bike and run down to the local harley shop to see how close they were.
Quote from: ducpainter on December 06, 2016, 09:07:39 AM
My 900 dyno'd exactly the same on the 'new' dyno with flatslides as it had on the 'old' one with stock carbs.
Right at 75hp.
Not bad ;)
Quote from: clubhousemotorsports on December 06, 2016, 09:39:39 AM
Not that it truly matters I was tempted to dyno a bike and run down to the local harley shop to see how close they were.
There's a dyno I want to run my Hyper on for the big numbers. Do a job and test it there and man, you are so good. [laugh]
My vintage race Triumphs have more time on the dyno than the track ;D My bikes are run on a Superflow, it functions as an eddy current or an inertia like a Dyno Jet.The shop owner wants the bike tuner to ride the machine on the dyno. some don't allow that.. On inertia ,the readings are about 6-8 percent higher than eddy current.. I use it for a tuning tool to compare before and after ....Bragging rights? Not so much....At any rate it's the best 100 bucks an hour I can spend to help tune the engine...And at the LSR track spend less time getting leaded race gas on my hands from changing jets.
I hear you. I work on carbs alot, and since unleaded pump fuel is laced with benzine :o, I'm grateful how dynos streamline the jetting process. Fuel injection is so sanitary with jet changes just a flick of the keyboard away.
Truckedup
Is he saying he gets different readings when he chooses to not use the eddy current?
Not superflow but our Dynojet 100 and 250i (eddy curent)were the same Hp numbers (1-2% off due mostly to age of the 100). The eddy current should be only acting as a break to add a load to the engine more than the inertia style. It should have little to no difference in a wide open throttle run as you do not have the break on for a full power run. They are used more for mapping, mid-throttle loads where the inertia type goes through the gears too fast with the break you can bog a motor down with excess load. It is not hard to get exhaust pipes white hot if you are not paying attention.
Bigger hp numbers can also be made by running in a room that is pressurized, playing with correction factors, on some dynos you can "adjust" settings and get wildly different readings. i had a monster s4R customer show me her Dyno reading where she had 140 rwhp at about 5000 rpm!
140 at 5000 rpm ;D
Quote from: koko64 on December 08, 2016, 07:11:32 AM
I hear you. I work on carbs alot, and since unleaded pump fuel is laced with benzine :o, I'm grateful how dynos streamline the jetting process. Fuel injection is so sanitary with jet changes just a flick of the keyboard away.
Yes, I see the car guys at the track with a the laptop making air fuel ratio changes.. But carbs and jets are much less expensive ;D And generally speaking for wot throttle racing that injection doesn't offer a power advantage..
I'll get my Ducati on the dyno this spring to check the main jets...I don't bother with air/fuel measurements for wot, simply jet for best power...
If you wonder what an old 650 Triumph looks like on the dyno...Running the engine from 3800 to 7500 rpm..I was doing this for hours and getting a little goofy....Bragging rights, 55 rear wheel HP at 7100 rpm and 46 ft lbs of torque... ;)
https://www.youtube.com/watch?v=-y94Yje2lzc (https://www.youtube.com/watch?v=-y94Yje2lzc)
Is that a conical rear hub I spy? :D
Quote from: koko64 on December 08, 2016, 07:33:19 AM
140 at 5000 rpm ;D
It must have been one of the super rare S8R.
Quote from: koko64 on December 08, 2016, 08:11:16 AM
Is that a conical rear hub I spy? :D
Ya, the frame is a 1975 oil frame the engine is more or less a 1970.I built the bike from a pile of parts.....It currently holds the 650 push rod modified production record in the one mile standing start..125.00 mph
Can a 900 Ducati two valve make 110 HP with enough reliability for land speed racing? It wouldn't stand a chance against the best OHC Japanese 1000's but might catch them off guard...
Quote from: Truckedup on December 08, 2016, 12:54:37 PM
Ya, the frame is a 1975 oil frame the engine is more or less a 1970.I built the bike from a pile of parts.....It currently holds the 650 push rod modified production record in the one mile standing start..125.00 mph
Can a 900 Ducati two valve make 110 HP with enough reliability for land speed racing? It wouldn't stand a chance against the best OHC Japanese 1000's but might catch them off guard...
I'd guess 110 honest rear-wheel horses from a 900 is a tough proposition regardless of reliabilty ... perhaps with the right dyno .... ;)
Great effort out of the little Trumpy! I've owned two '73 T140's that were passionate love affairs.
Your question is worthy of it's own thread. Speeddog, Eric, DuckStew and Dirty Duck may have some input for you. 110 is more likely with an 1100 motor but maximum effort 900 motors reportedly can go to 100hp if worked to 944/964 and major head modifications.
Quote from: MonsterHPD on December 08, 2016, 01:42:33 PM
I'd guess 110 honest rear-wheel horses from a 900 is a tough proposition regardless of reliabilty ... perhaps with the right dyno .... ;)
;D
There must be a SOHC 2 Valve class.
Quote from: koko64 on December 08, 2016, 01:57:48 PM
;D
There must be a SOHC 2 Valve class.
Don't say that to the scta people... [Roll]
You guys run event gas? At Bonneville you can run ERC110k in the gas class.
Naturally aspirated on pump gas, I suspect the limits are fairly well explored.
The blower bike started as a 1000ds. Dual spark being one of the mods to make a 900 fast, and the class breaks normally being at 1000 make it seem like a better starting point.
Quote from: Speeddog on December 08, 2016, 08:14:52 AM
It must have been one of the super rare S8R.
The rare V8 32 valver. ;D
Quote from: Dirty Duc on December 08, 2016, 02:27:40 PM
Don't say that to the scta people... [Roll]
You guys run event gas? At Bonneville you can run ERC110k in the gas class.
Naturally aspirated on pump gas, I suspect the limits are fairly well explored.
The blower bike started as a 1000ds. Dual spark being one of the mods to make a 900 fast, and the class breaks normally being at 1000 make it seem like a better starting point.
Did I stumble into racing politics? ;D
Maybe a carbed 1000 with headwork and hotter cams? Is that allowed?
1000 cc push rod 2 valve Guzzi can crack 100 hp with a lot of money... [evil]
QuoteI don't bother with air/fuel measurements for wot, simply jet for best power
Keep in mind unless you are towing the Dyno on a flat bead trailer at speed when doing this you are leaner when you are actually riding the bike and your jetting will be leaner causing the power you think you have to be lower. You can guess with adding high speed fans in front of the dyno but you really should be finding peak HP on the dyno and then going a tad richer on the mains so you are not too lean when adding 100mph wind.
peak power often is around 13.5-1 but unless you are dealing with a fuel injected bike that will use airbox pressure you almost always want to be closer to 12.5-1.
As to the 110hp 900 I see no reason it would not be possible on somebody's dyno (probably not mine) I have seen 900's in the 90's with 50% builds so an all out build might just get there. I do have a couple 985 motors that are pretty close to full built. The best case would have been one that used to have tipped up port heads and all the lightened internals (rods,crank etc)and as a race bike running too high for street compression it might have been there when fresh. The problem is that is a lot of $$$ to spend on a motor to get it there.
I am going to be building a 1100 evo motor this winter/spring that is going to be a pretty full build. So far 107 on my dyno is the highest hp 2-valve. IIRC a st3 which is not aircooled is about 100hp stock and I am putting some hi comps in one this winter as well so lets see how the 3 valver works with a little compression.
Quote from: clubhousemotorsports on December 09, 2016, 07:34:38 AM
Keep in mind unless you are towing the Dyno on a flat bead trailer at speed when doing this you are leaner when you are actually riding the bike and your jetting will be leaner causing the power you think you have to be lower. You can guess with adding high speed fans in front of the dyno but you really should be finding peak HP on the dyno and then going a tad richer on the mains so you are not too lean when adding 100mph wind.
peak power often is around 13.5-1 but unless you are dealing with a fuel injected bike that will use airbox pressure you almost always want to be closer to 12.5-1.
As to the 110hp 900 I see no reason it would not be possible on somebody's dyno (probably not mine) I have seen 900's in the 90's with 50% builds so an all out build might just get there. I do have a couple 985 motors that are pretty close to full built. The best case would have been one that used to have tipped up port heads and all the lightened internals (rods,crank etc)and as a race bike running too high for street compression it might have been there when fresh. The problem is that is a lot of $$$ to spend on a motor to get it there.
I am going to be building a 1100 evo motor this winter/spring that is going to be a pretty full build. So far 107 on my dyno is the highest hp 2-valve. IIRC a st3 which is not aircooled is about 100hp stock and I am putting some hi comps in one this winter as well so lets see how the 3 valver works with a little compression.
Yes, the dyno can be lean compared to the race track...Off the trailer with no jetting changes the bike ran 128.2 mph at the 1-1/2 mile track at Maine setting a new track record at that time...I went richer on the Mikuni 34 MM flatslides and the speed picked up 1/10 mph..Too close to make a call....I run leaner that the competition and go faster...of course the detonation risk is evil on the 1930's technology Triumphs...
I mentioned 110 HP just for an example. and not as a dyno queen...I have no real idea on the durability of 2 valve engines and if real power means special cranks ,rods and so on that gets real expensive... Thanks for your info...
I am going to assume you are talking of the old air force base in Maine for top speed runs or are you at the oxford drag strip?
Different bikes will take different jets it is just ballpark figures when you are getting jet sizes from someone else. There are too many variables between bikes for what you are doing. your Dyno will be the best judge of what works on your bike. Yes Lean can bring in detonation and that can get expensive so fat is safer within reason.
A safe mild build on a 900 motor is 80's at the rear wheel up about 10hp and +10 on torque the motor would be stock reliable. porting does not hurt reliability either. When you start getting into exotic materials like Ti rods, crazy cams or pushing limits with squish this is when you start to see a drop in practical reliability and need to treat the additional costs as maintenance. At 110 or 100hp I would also expect a shorter life before the cases cracked.
Loring AF base...We also raced at the one mile track in Ohio but that closed this fall...i use aftermarket rods on the Triumph so the stock crank becomes the limiting factor at about 70 HP and or above 7500 rpm..
I have seen 900 Ducati engines for reasonable prices. I was thinking of pulling the stock engine building another one and 80 hp at the rear wheel should do the job.. But at my age you might think the stock engine is enough to scare me... ;D
No problem with a stock or mildly built 900 motor. They are very good motors with easy to use power.
Big bore gets you more torque than just hi comp and cleans up the cylinder at the same time. 944 or 950 and there is lettle added risk of losing cylinder seal.
lighten the flywheel and mount a bank of keihin FCR's and you have a great setup. IMHO one of the great engine combinations.
I like my 900.
That combo makes a wonderful street motor.
Quote from: clubhousemotorsports on December 09, 2016, 04:23:43 PM
No problem with a stock or mildly built 900 motor. They are very good motors with easy to use power.
Big bore gets you more torque than just hi comp and cleans up the cylinder at the same time. 944 or 950 and there is lettle added risk of losing cylinder seal.
lighten the flywheel and mount a bank of keihin FCR's and you have a great setup. IMHO one of the great engine combinations.
How much compression can be tolerated on 91 octane pump gas with a cam similar to stock ? 9.5? Will a lighter flywheels make the engine too lumpy at low speeds?
A stock Monster is supposedly 9.2:1, and will run fine on 87.
My 853 has Pistal pistons reportedly somewhere around 12:5:1 and I can run 91, without pinging, if I don't find 93.
On a street motor running pump premium 10.5:1 to 11-1 is a safe bet. some of the 11:1 hi comps can ping if you do not set it up correctly. These will be domed pistons so some times you can get away with higher compression ratios by dual plugging. personally I would go with a known big bore/high comp non- race piston and you should be fine.
The Ducati flywheel is about 4lbs stock, we have them cut down to 2 lbs and there is no issues with idle or being lumpy. There are aluminum flywheels that are measured in ounces and many owners love them but I personally like to keep a bit more mass.