VR6 dyno plot!

[Col_M 0]

Hi, has anyone got a dyno plot of a VR6 from a rolling road day? as close to standard as possible would be best.

I need it for a uni assignment where i'm modeling the theoretical acceleration and performance in matlab simulink.

Cheers

Col

edit: pretty please

[Col_M 0]

I've found lots of plots by going onto google image search and entering "VR6 dyno" (without speech marks), but most of the plots i can find are American and give peak power as about 155bhp, surely this is at the wheels because otherwise it's pathetic, i'm sure all the plots i've seen in the UK have been corrected for transmission losses and give an estimated power and torque at the flywheel.

Does anyone have a plot that has been corrected for transmission losses?

Please, i'm sure somebody on here must have a printout that they scanned

look here http://www.dynospotracing.com/a3vr6.htm it clearly gives the standard power as 155bhp and all of them are like this that i can find

[Eat this 2]

yes the yanks use wheel power they dont bother with corrected figures as thyr inherintly innacurate to a certain drgree

[Col_M 0]

Cheers that's cleared up

To be honest i don't see what the problem is with the innacuracies of corrected values, power runs are usually only done for the fun of it and nothing is read into the results, it's just bragging ammo down the pub or forum so accuracy is hardly critical.

When cars are tuned on the rollers i'd guess that it is done by comapring relative values, for example, if you adjust this does it improve the torque from the result i got a few seconds ago, absolute values are of no use because you are comparing relative values. If the rollers are innacurate and underreading by say 2% then all the values will be 2% down but the best setup with still give the best figure. If that makes sense lol

tbh i have no experience of rolling road dynos, i've always used engine test beds with hydraulic dynos

anyway i'm still waiting for someone with a plot (impatient bugger aren't i)

[badboyV6 4]

a friend told me that the transmission loss was calculated by the time the car took to come to a halt (or the rolling resistance of the transmission) i always wondered how this was calculated....

[VRmonster 1]

When cars are tuned on the rollers i'd guess that it is done by comapring relative values' date=' for example, if you adjust this does it improve the torque from the result i got a few seconds ago, absolute values are of no use because you are comparing relative values. If the rollers are innacurate and underreading by say 2% then all the values will be 2% down but the best setup with still give the best figure. If that makes sense lol

[/quote']

well in fact, when tuning a car on a rolling road, you arent actually aiming to meet a certain power. your more tuning the negine to run at its highest possable fuelling/timing before it starts pinking, so the figures reached are mainly just to guage the strength/power of an engine. nothing to do with the tuning if you see where im coming from.

you could tune a car on the street just as well as on a roaling road if you have an afr meter, you just wont have a power figure at the end of it. plust its easier to get the car to run different loads, thus making the car more comfortable to drive around the town.

i think there may be some really old slips from the first rr shootout still in the members section. think its time pete chimed in and sorted them out for ya.

[Eat this 2]

do u want a bhp graph or torque imho bhp graphs r useless (as u say bhp is basically pub ammo) the torque graph tells you what the engine is doing

[Craig 0]

The flywheel figures gained from a rolling road are misleading, as the procedure for obtaining them is fundamentally flawed.

After the at the wheels reading is obtained, the operator puts the car in neutral and allows the wheels to slow down of their own accord, to measure "Coast down" losses.

This is supposedly to gain an idea of transmission losses, but therein lies the error. Back to that in a moment ...

Anyway, the reading for the "Coast down" is added to the at the wheels figure and the result is supposed to represent the power at the flywheel.

The problem is that with the vehicle in neutral, the engine is not engaged with the drivetrain and therefore any losses registered are primarily due to drag from the tyres, rather than transmission!

There is a lot of good information on the Puma Racing website, from where I learned the above. Visit [link]http://www.pumaracing.co.uk and look in the Power, Torque And Vehicle Dynamics section (Under "Technical Articles").

[Col_M 0]

Yeah i need the torque, as you know power is just a drivation of torque and engine speed. It doesn't really matter if the plots are inaccurate, as long as they are there or thereabouts is fine. I can add into the report that the results were assumed to be innacurate and a way to improve this would be to use a more accurate dyno, ie engine dyno, that'll get me extra marks so that's why i don't mind.

cheers