Drivetrain losses
Discussion
Ive been on 3 different UK dynos on my noble mostly slightly differing states of tune so not directly comparable.
Last one was a hub dyno and they wouldn't even entertain a flywheel estimation... its this much at the hub your guess of flywheel figure is as good as ours.... the other claimed 60bhp and 100bhp... all are claimed to be conservative and more accurate than everyone else's.
Anyhow speaking to a respectable american firm who specialise in tuning extreme nobles they have a car with a comparable engine to mine.... they told me they were running massive flywheel power, but that they had 200bhp drivetrain losses?.... at reasonably close wheel power levels to what i run.
Other than engine dyno back to back with a hub dyno is there a way to test these losses and have conclusive figures?
Last one was a hub dyno and they wouldn't even entertain a flywheel estimation... its this much at the hub your guess of flywheel figure is as good as ours.... the other claimed 60bhp and 100bhp... all are claimed to be conservative and more accurate than everyone else's.
Anyhow speaking to a respectable american firm who specialise in tuning extreme nobles they have a car with a comparable engine to mine.... they told me they were running massive flywheel power, but that they had 200bhp drivetrain losses?.... at reasonably close wheel power levels to what i run.
Other than engine dyno back to back with a hub dyno is there a way to test these losses and have conclusive figures?
ok this sounds similar to what i was thinking.
so basically for a noble that runs a mondeo ST220 V6 engine and gearbox (a fwd car)... even though its making 700hp at wheels its not going to be loosing 200bhp through the drivetrain and thus have 900bhp at fly.... more like 70-100bhp max?
what would you expect the difference in figures between a hub dyno and a set of decent rollers?... its just the wheels and tyres that are removed?
so basically for a noble that runs a mondeo ST220 V6 engine and gearbox (a fwd car)... even though its making 700hp at wheels its not going to be loosing 200bhp through the drivetrain and thus have 900bhp at fly.... more like 70-100bhp max?
what would you expect the difference in figures between a hub dyno and a set of decent rollers?... its just the wheels and tyres that are removed?
Pumaracing said:
Ok I'm now thinking you might be feeding us bum information. Looking at your previous posts and other stuff on the net your rolling road figures will already have been converted to estimated flywheel numbers and won't be wheel bhp. So I'm now thinking you have an estimated 700 bhp flywheel bhp not wheel bhp which will probably be in the low 600s.
So a hub dyno figure would be mid 600s bhp.
No im not feeding you bum information, your missreading what I have said So a hub dyno figure would be mid 600s bhp.
In the states they have a car they claim 900bhp flywheel, and said it was 700hp at wheels... thus 200bhp losses hence my confusion as its the same engine and box with same mods to box and drivetrain.
for clarification my car made 575 wheel HP in an old guise which was estimated as 626bhp at the fly at the time.... I then had it pushed a little further with new engine mods, it 'felt' a lot faster on pure wastegate pressure than the previous guise... when it was dyno'd this showed it had increased 60bhp on low boost, which matched what it felt to drive.
High boost this iteration made 595hp (i think) at the wheels and 700bhp estimated flywheel... it felt and was a lot faster than the 626bhp iteration.
Ive now had it on a hub dyno and it made mid 600bhp at hubs... no estimation of flywheel was made but it is running more boost than before and is faster any thus is more powerful.
So Im not unhappy or worried about the cars performance... I just cant believe how vastly different peoples claims for transmission losses... Personally I cant see how the drivetrain losses can be over 100bhp... I also don't beleive a wheel and tyre could loose over 30bhp (well not my ones)... that's a HUGE amount of heat or noise to dissipate and they would simply melt and or explode as thats over 22kw and is lot of electric fires of energy lol
Edited by andygtt on Wednesday 1st October 12:27
stevieturbo said:
Whether it's your fancy or not...
1/4 mile traps, 1/2 mile traps etc are far better and more reliable indicators of actual power to the ground.
Dyno's just vary too much to try and make comparisons elsewhere.
And trying to compare with US dyno's....is even more difficult. Everything is bigger over there !
Or if standing starts arent great. Some of the 30-130 or 60-130 type pulls are also a good indicator of power and can be far more reliable measured across continents ( unless you're running downhill with a massive tailwind )
I don't have telemetry from 60-130mph (unless I stick bits of telemetry together)... but I do have 70-140mph of 5.3 seconds or 70-130mph 4.6 seconds with 2 people in the car... so 1030kgs plus driver 95kgs and passenger 90kgs... so 1215kgs... I don't have 1/4 mile times or anything yet.1/4 mile traps, 1/2 mile traps etc are far better and more reliable indicators of actual power to the ground.
Dyno's just vary too much to try and make comparisons elsewhere.
And trying to compare with US dyno's....is even more difficult. Everything is bigger over there !
Or if standing starts arent great. Some of the 30-130 or 60-130 type pulls are also a good indicator of power and can be far more reliable measured across continents ( unless you're running downhill with a massive tailwind )
Wont be anything like as fast as your monster/car though lol
Pumaracing said:
andygtt said:
I don't have telemetry from 60-130mph (unless I stick bits of telemetry together)... but I do have 70-140mph of 5.3 seconds or 70-130mph 4.6 seconds with 2 people in the car... so 1030kgs plus driver 95kgs and passenger 90kgs... so 1215kgs... I don't have 1/4 mile times or anything yet.
I do. I ran your car through my vehicle performance simulation programme. So 1030kg plus two fat b
ds, assume 0.85g grip off the line (0-60 mph 3.2s) from best quality road tyres and mid engine rwd weight distribution, 0.2 second gearchange time as I recall you telling John down the pub how you'd just managed to obtain those with practice.I get good agreement to your 70-140 mph time with 720 bhp. Your 70-130 times are wrong. They should be exactly 1 second quicker than 70-140 as 1 second is your 130-140 time. 1/4 mile is 10.5 at 150 mph with perfect launch and gearshifts. With drag slicks and optimised gearing that could be 9.2 seconds at 154 mph.
Im hoping for quarters in the high 9's... given that with basically doing a burnout on a cold evening with cold tyres I did 0-60 in 3.4s and I have managed full throttle in 1st on hot tyres.... I've only done 1 full launch since i fitted the motec.
Also the Ultima 720 with same weight and similar power managed 9.9s quarters... and according to my telemetry I am a lot faster which knowing the engine builder means their engine isn't quite 700bhp.
My motec telemetry says I have done 130-140mph in 0.7s although I changed at just over 140 so the 140-150 was 1.2s.
I must say that I have seen the value that telemetry offers to racers... for example comparing 2 different runs down the same straight using full throttle one was 0.5s faster as I rev'd the car to close to 8000rpm than in one when i was changing up at 7300rpm even though the peak power is actually around 7000rpm and comes in at 6000rpm so I changed into the 'power band' in both instances.
My goal of the thread was not to validate my power figure, just to get a better idea if transmission losses could actually be tested in some way rather than guessed (sorry estimated)...
You all seemed to have confirmed what i have always believed... there is a lot of bull out there with no real way to prove or disprove it.
Pumaracing said:
andygtt said:
I find this very Interesting, although in truth I'm not sure if you taking the piss out of me or not lol
Would I take the piss out of a fellow accountant? Moi?Anyhoo, details of the capabilities and design of my vehicle performance computer simulation programme are here.
https://web.archive.org/web/20110903091550/http://...
so you either have a lot more information on specifics of my car or have made some detailed assumptions for your calculations... i remember you once promising to calculate my clutch and flywheel gains from you spreadsheet.
Im also guessing you have gear ratio's for the box etc?
I bought my engine for my Ultima from the same company that the Ultima 720 comes from.. it was claimed as bench dyno'd by the tuner as 526bhp... I took the engine out and had it bench dyno'd by Peter Knight and it cam out at 490bhp... Id paid for a 500bhp engine so was fairly happy.
We then removed the dyno headers and fitted the Ultima ones I ran and it only lost another 10bhp... but in mid range it lost 60ftlb.... my car was same weight as the Ultima 720 and I did quarter mile times of 11.4 @ 126mph at the pod were they did their runs.
Given cars like the Enzo and F1 my times were pretty much were you would expect... I have a mini spreadsheet I wrote to predict times as well, its not as advanced as yours but wasn't that inaccurate (a few cars didn't fit the model though).
Do you remember Autocar testing an Ultima in their 0-100-0 way back in 2002?... that was me and I wasn't popular with the factory after that as they had continually refused to provide a car
So I am very very confident the Ultima 720 has a lot more power than 500bhp...
Incidentally I find my noble has a lot more traction than my Ultima had!
We then removed the dyno headers and fitted the Ultima ones I ran and it only lost another 10bhp... but in mid range it lost 60ftlb.... my car was same weight as the Ultima 720 and I did quarter mile times of 11.4 @ 126mph at the pod were they did their runs.
Given cars like the Enzo and F1 my times were pretty much were you would expect... I have a mini spreadsheet I wrote to predict times as well, its not as advanced as yours but wasn't that inaccurate (a few cars didn't fit the model though).
Do you remember Autocar testing an Ultima in their 0-100-0 way back in 2002?... that was me and I wasn't popular with the factory after that as they had continually refused to provide a car
So I am very very confident the Ultima 720 has a lot more power than 500bhp...
Incidentally I find my noble has a lot more traction than my Ultima had!
Im not being any of those things... as I say I bench dyno'd my ultima engine and did the speed runs myself... the Ultima 720 is same weight but 1.5 seconds faster than my ultima was so must be more powerful.
To be clear I don't think its 700bhp but I do think its a lot more powerful than mine was as its a lot faster... also the engine was a lot higher spec so should be more powerful as well.
worth mentioning the Ultima has a flywheel 4 times the weight of mine and higher transmission losses IMO, maybe thats a factor?
To be clear I don't think its 700bhp but I do think its a lot more powerful than mine was as its a lot faster... also the engine was a lot higher spec so should be more powerful as well.
worth mentioning the Ultima has a flywheel 4 times the weight of mine and higher transmission losses IMO, maybe thats a factor?
interesting that its a long way from a linear curve, doesn't even make sense to me (less power loss at 3500rpm compared to 3000rpm?)... id always assumed it would be a smooth curve of some kind.
Maybe oiling is playing a part that at certain box speeds the gearbox is more efficient and thus saps less power?
Maybe oiling is playing a part that at certain box speeds the gearbox is more efficient and thus saps less power?
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