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I asked this sometime last year but could not find the thread. Does anyone know how to translate RWHP to approximate HP at the flywheel?

Thanks, Tim
 

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There is roughly, very roughly a 15% less of horsepower through the drive train. Take rear wheel horsepower and divide by .85 and it will approximate the flywheel horsepower. Automatices are a little more than manuals
 

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There is roughly, very roughly a 15% less of horsepower through the drive train. Take rear wheel horsepower and divide by .85 and it will approximate the flywheel horsepower. Automatices are a little more than manuals
:agree: Some say 15% some say 18%. My numbers are much more reasonable using 15%.

15% = 577hp for my car
18% = 592hp

I would guess 15% is closer.

:cheers:
 

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Thanks guys. I was curious because my car is being modded now and I was at the shop yesterday to watch a dyno pull and he got 360 to the wheels after kooks headers and x pipe with high flow cats, corsa touring exhaust, vararam air intake, 160 degree thermostat and throttle body spacer and new plugs and wires. It baselined at 335RWHP. Software is arriving today for the custom tune and he's expecting for another 30-40hp. You think that's feasible?

Thanks again~ Tim
 

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My A6 is exactly 16.5 %:D
How would you know this? An engine dyno would give you Brake HP numbers (most are a little over the advertised 400hp) but your A6 is hard to get accurate RWHP numbers because it does not have a gear that is 1.00/1.00 ratio so you are always getting gear multiplication figured into your rwhp Dyno numbers:huh:

:cheers:
 

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How would you know this? An engine dyno would give you Brake HP numbers (most are a little over the advertised 400hp) but your A6 is hard to get accurate RWHP numbers because it does not have a gear that is 1.00/1.00 ratio so you are always getting gear multiplication figured into your rwhp Dyno numbers:huh:

:cheers:
I took the baseline dyno and compared it to the advertised 400HP GM says the car makes and used that percentage throughout the modification process. Maybe not scientific, but as good as anything else out there.If you have a better way, I'm all ears, but with it being the new tranny on the block, I think my numbers are pretty good. If I'm off, it's to my loss, not favor, so thats cool.My 422.1RWHP =491.7BHP I take the dyno and add the 16.5% to the rwhp numbers rather than the bhp and reduce for the rwhp numbers.
 

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Thanks guys. I was curious because my car is being modded now and I was at the shop yesterday to watch a dyno pull and he got 360 to the wheels after kooks headers and x pipe with high flow cats, corsa touring exhaust, vararam air intake, 160 degree thermostat and throttle body spacer and new plugs and wires. It baselined at 335RWHP. Software is arriving today for the custom tune and he's expecting for another 30-40hp. You think that's feasible?

Thanks again~ Tim
30-40 rwhp from a tune is a little high in my opinion, but anything is possible. Just be sure they make it streetable. I'd rather lose a few HP than not be able to drive the thing.
 

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I took the baseline dyno and compared it to the advertised 400HP GM says the car makes and used that percentage throughout the modification process. Maybe not scientific, but as good as anything else out there.If you have a better way, I'm all ears, but with it being the new tranny on the block, I think my numbers are pretty good. If I'm off, it's to my loss, not favor, so thats cool.My 422.1RWHP =491.7BHP I take the dyno and add the 16.5% to the rwhp numbers rather than the bhp and reduce for the rwhp numbers.
That's as good as anything else but with your A6 it is not as pure as a car with a 1.00 gear.

FYI. My car stock dyno'd at 342 which if I use your method equates to a 17% loss. Since then I have changed some driveline parts as well as the engine. Now it is just a guess but 590+ seems a little high for my car.

:cheers:
 
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