I just had some work done to my 2011 GSR and it pulled 310 whp at 6658 rpm on the AWD dyno - any idea how this converts to HP at the crank/flywheel?

 

I think most people assume ~20% drivetrain losses.....

 

Roughly 15-20% more I think. So about 360 give or take I'd say.

 

thx

 

Approx 80bhp loss on an evo its not a percentage. Oh and not all dyno's actually give wheel horsepower, some are estimated flywheel already.

 

@20% drivetrain loss you would be making appx 387hp at the crank.

Also you ALWAYS lose a percetange, not just 80hp.

Plus most Evo drivetrain's lose roughly 22-25%.

 

Sorry but that is not true. Measure the coastdown losses properly and its quite clear what the losses are. The wheels don't get heavier when you double the power and they are the main part of the loss.

 

You're right it is not necessarily a fixed %. But to say it is always 80hp is equally bad logic.


Coast down method is not always accurate either. The test is not dynamic, it is done while coasting, not accelerating, it only captures steady-state drivetrain loss and rolling resistance. Not a true indicator either.

It is hard to correlate the two. Especially when modding.

 

I said approx 80bhp. But fit bigger heavier wheels it goes up. This is why fhp figures can get out of hand because most people aren't looking at the losses properly and some dyno manufacturers are keen to have the biggest numbers. Just saying

 

I do agree with you to an extent. Look at some Evo owners claiming to have 700BHP when their car makes 500whp on the dyno. Just because they used to percentage method. It is really hard to correlate the two. You just need to accept they are two different numbers; frankly I don't really care what my car has at the flywheel either.

 

I am merely curious and was looking for an approximation...as a muscle car guy I am not used to looking at whp numbers......

 

More load (torque) on the rotating parts of the driveline = more friction = more loss. It's not necessarily a steady percentage, but it's definitely not a constant 80HP (or any other number).

Basically, the force needed to accelerate all the rotating parts of the engine is constant, but the friction between the parts is not, and since that friction changes with the normal force from one part against the other (load on the parts/torque the engine is putting out) coast down won't accurately portray it either.

But really, dynos read WHP wildly differently, who cares how exactly you modify an already inexact number

 

i think the % is the most realistic approach to get any kind of gain numbers.
We can safely say it is more then 15% drive train loos with an Evo. It is an easy count if you get a BHP number from the manufacturer and you get a bone stock base evo numbers . You will get some kind of rough number and % you can go with if its must. Just make sure you do this on a same dyno where you get a tune.

By the way no whp or bhp numbers really is what matters. I think the difference between your base line and the after tune-install number matters. So you will know it was a worthy upgrade or not. The two number % is the real number you are looking for. And that should be a same wont matter which dyno you run it. If you really must have a number

 

Regardless of dyno numbers, real world is ~17% DTL for Evo's; but not nearly as Subies @~22% DTL

 

Torque @ RPM is what we should be talking about!