[57teeburd]

Can someone tell me the formula for calculating rear wheel HP to rated HP? I have a 289-4bbl that says 150 or so to the rear wheels....seems a little lame for a new engine?? Thanks!

 

[arnoldtx]

What type of dyno did you run on? 15 - 20% loss at the rear wheels but it depends on the type of dyno can be as high as 30%.

 

[FEandGoingBroke]

the 289 stock had 185 and 210 HP at the flywheel in stock form, I can imagine 150 to the wheels as fairly accurate.

 

[PSIG]

There is no formula. You used a chassis dyno, so the difference to FWHP is entirely dependent on your particular chassis setup. Changing tire pressure by 5 psi or changing the U-joint angles can give or take 10 hp. HP figures from a chassis dyno are only for comparative tuning on the same car and only generally relate to other cars - even with the same engine. If it makes you feel better, an average of over 40 random small block cars (Ford, GM, MOPAR, etc.) of 273 to 360 C.I. with aftermarket carbs, intakes and headers (otherwise stock) was 168 hp and just over 200 ft/lb TQ. I agree, your 289 would seem to fit right in, assuming the same mods.

David