Well I decided to take the 8 to a local rolling road centre today so I could obtain some written proof of figures my car's producing.

My 8 has been remapped by Gerry @ Phoenix, but apart from that its stock (engine wise anyway http://www.8er.ch/forum/images/smilies/icon_grinsen2.gif)

Well I'm pleased to report back that it reached 299.9BHP, which I'm well chuffed at and maybe it finally shows that there is gain to be obtained with having the ECU remapped.

So the graph is saying you reached about 238HP at the wheel? Am I reading that right?

I'm a little confused at how the dyno can measure flywheel HP. I assume it's just doing some assumptions and performing a calculation to estimate flywheel HP?

Based on the bottom part of the pdf...it says 227 HP at the wheels (BTW...Where are the TQ numbers? HP is derived from the torque).

Assuming a 70 HP loss of the drivetrain the measured FWHP comes to 297 HP which is 11 HP gain from BMW spec of 286 FWHP.

My baseline dyno of my old Dinan chipped 840 came at 228 HP and 269 TQ at the wheels on a very hot summer day.

I'm not sure where the torque figures are, the guy who did the run did mention that as its an auto it cannot be locked into gear so does make the run harder, but I'm not sure.

Faisal, repeat after me---E31 power train loss is not 70 HP, more like 55- 60 HP, I have never seen any E31 drivetrain loss more then 65 HP and that was with a diff with 140 weight gear oil and a very cold day, first run!

I know we are splitting hairs here but again, to try to translate wheel HP to crank HP is not going to be very accurate or a reliable way to judge. We should all be on a campaign to state what we measure and not make any assumptions.

To make sure that no one thinks this is my idea, there are many articles by the wheel dyno manufacturers that state there is no reliable way to get crank HP or torque numbers from a wheel dyno with any accuracy or repeatability!

All to often people will jsut throw a "20% or 25%" power train loss just top make the numbers come out right or make them bigger! AND, power train loss, while a real number, does not follow the input power in a linear fashion. If you have 400 HP at the crank and and use 20% that suggests wheel hp of 320 HP and if you up that power to 500 HP at the crank that would suggest a wheel HP of 400, so with the same drivetrain by adding 100 HP the losses go up by another 20 HP? NOT A REASONABLE assumption. Yes HP losses will go up as power input to the drivetrain goes up but not in a "1 for 1" or fixed % relationship.

E31 power train loss is not 70 HP, more like 55- 60 HP
E31 power train loss is not 70 HP, more like 55- 60 HP
E31 power train loss is not 70 HP, more like 55- 60 HP

:):):):):):):):)

E31 power train loss is not 70 HP, more like 55- 60 HP
E31 power train loss is not 70 HP, more like 55- 60 HP
E31 power train loss is not 70 HP, more like 55- 60 HP

:):):):):):):):)

:buttrock:buttrock:buttrock

Ok Ok, I get the point!:lol

I case you guys want to read a bit more here is a link to the whitepaper I did awhile ago. (2005)

http://www.mwrench.com/Whitepapers/Dyno.pdf

I have updated information that confirms the original thesis, but, have not taken the time to document it because I had thought that this controversy had finally come to a realistic conclusion.

Thanks for posting the whitepaper. Makes perfect sense. You're right, the contraversy should be put to rest.

Cheers

Well I decided to take the 8 to a local rolling road centre today so I could obtain some written proof of figures my car's producing.

My 8 has been remapped by Gerry @ Phoenix, but apart from that its stock (engine wise anyway http://www.8er.ch/forum/images/smilies/icon_grinsen2.gif)

Well I'm pleased to report back that it reached 299.9BHP, which I'm well chuffed at and maybe it finally shows that there is gain to be obtained with having the ECU remapped.

Jeesh Wayne,

Couldn't you at least have farted in the air filter before that run and at least cracked the 300 bhp mark?:eek:

Gerry.

Jeesh Wayne,

Couldn't you at least have farted in the air filter before that run and at least cracked the 300 bhp mark?:eek:

Gerry.

Only wish I had thought of that, I didn't even think I would get so close to 300.