[Torquemonster]

I posted a thread on this very topic a few weeks ago on the org site - posted up the best and most scientific data i could find and there was some good comments made by others.

Bottom line - there are some fixed loses and variable losses - as you would expect - therefore a flat percentage is not always accurate....however, as a rule of thumb for rear wheel drive this formula works better than anything else we've found so far...

1 - Take corrected rwhp from an industry standard chassis dyno

2 - add 10hp

3 - Divide result by 0.88

= Engine Hp aprox.

This will give a lower figure than many popular conversions but is more realistic to actual numbers run.

To reverse:

1 - Take engine dyno corrected hp

2 - subtract 10hp

3 - multiply by 0.88

= RWHP.

Here's an example - the 649rwhp John just dyno'd + 10 = 659/0.88 = 749hp at crank.

Yours Smokin - 777rwhp + 10/.88 = 895hp!

Paolo's - 888rwhp + 10/.88 = 1020hp!

engine makes say 650hp - 10 x 0.88 = 563rwhp

This formula appears to be quite close to what a Viper will produce.