can anyone tell me how much horsepower loss there might be from the engine to the rear wheels? I have a 65 289 hipo it dynoed at 258 at rear wheels. Just wondering what I might have at the engine. Was told 100 horsepower loss, through the drive train that sounds low to me, it is a 4 speed.
thanks

 

I always thought that arule of thumb forthe difference was closer to 50hp for a manual and 75 hp for an auto.

 

the rule of thumb is usually a 15-20% hp loss through the drivetrain. So, if you dynoed 258rwhp, you're losing about 38-48hp from the transfer...which means at the flywheel you're probably seeing ~290-300hp.

 

its a simple equation, ur loss through a manual is about 15 percent. so
u take the 258 u made, multiply that by 1.15 cause u want the extra 15 percent u lost, and then u will have ur number. i did and got 296.7 hp at the flywheel.

 

If you are using an 8 or 9 inn Ford differential that alone uses about 7% of your gross hp. That would put you at around 275-280 not including transmission loss. Not too shabby for a 271/289. Bet you aren't running a factory cam...maybe a Crane Fireball? What about headers?

 

does my factory AC unit drain HP too? I could go without it ...

 

not while its not running it doesnt.... while off its just turning the pulley which is like less than 1 hp if i had to guess

 

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