WHP v. FHP
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WHP v. FHP
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?
#5
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.
#7
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.
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#8
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.
Last edited by HAHAV8; Jan 31, 2012 at 02:08 PM.
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#10
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.
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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.
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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
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
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Last edited by mirkendargen; Jan 31, 2012 at 07:46 PM.
#13
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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
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
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Last edited by Robevo RS; Jan 31, 2012 at 08:26 PM.
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