Comments on: Dyno Day at YarrowSport – Ians version!

By: Chapel

Chapel — Wed, 22 Feb 2006 00:49:25 +0000

He’s talking about drivetrain loss.
The number represented by a chassis dyno is power at the wheels.
To ‘estimate’ crank horsepower, you do this simple equation:

BHP – driveline loss% = WHP

Generally, FWD cars get between 12 and 18% driveline loss (I use 15% as a standard)

So, let’s say you made 150whp. divide 150 by .85 (15% driveline loss) and you get 176.47bhp

Pretty simple, however all these numbers are estimates as there is no standard DEFINED driveline loss. What I do is divide by 12, 15 and 18%. Generally, it’s somewhere between there. I use dynos to see if the car is running right more than anything.

By: Ian C.

Ian C. — Thu, 10 Nov 2005 00:18:04 +0000

Any chance you can explain that further – all these wheel/crank/hp/torque/rpm figures get me confused easily

By: roccodart440

roccodart440 — Wed, 09 Nov 2005 19:32:43 +0000

THose numbers are actually better than what JCW claims. Your getting about 214 at the crank.

By: Chris K.

Chris K. — Mon, 13 Sep 2004 19:48:34 +0000

I imagine the claimed 200BHP from JCW is “at the crankshaft.” JCW undoubtedly uses and engine test bench w/ dyno and gets their figures from there. Driveline “slop” and friction rob 10-15% (sometimes more) of you power “at the crank.”
Good numbers!

By: RB

RB — Mon, 13 Sep 2004 14:49:06 +0000

Looks like you had fun that day. I wish I knew more MINI folks.
I know it would be nice to have more pony’s but for the cost of the JCW’s package I expected a lot more.
The movie was cool thanks Ian.
BTW…my wife did order the A4t Quattro with the Premium & the Ultra Sport package this weekend. That is if the dealer will come to her price. We noted the HP as you suggested but it’s fine for her.
…RB

By: Ian C.

Ian C. — Mon, 13 Sep 2004 11:28:30 +0000

Thanks … I am not much bothered by the numbers because I know how GBMINI drives

By: db

db — Mon, 13 Sep 2004 07:09:37 +0000

Don’t get to down on the lower than expected numbers. Remember that the dyno gives you horsepower at the wheels, and usually the manufacturer specs horsepower at the crank shaft. That’s the difference. Besides that, 191HP is nothing to sneeze at! You still have me beat by 84…