jmelgin

Well, I strapped my toy on the dyno today to see what kind of numbers I could pull. My rig has a 5.7L Hemi (by SLC), 6-spd manual, 3.21 gears, and 35" tires. Best run generated 280 hp & 327 ft-lbs torque at the rear wheels. Putting down that much hp and torque at the rear wheels is pretty darn good in my opinion!

Stuka

Swap in some 4.56 gears and those numbers will jump up significantly. Probably put down closer to 320hp or so. What gear was the transmission in?

nick p

Could you explain how changing the axle ratio will change the RWHP?

Nick

Stuka

It all has to do with torque and leverage. Low gearing is basically the same as using a longer lever. Which means you will lose less torque. Since he has 3.21 gears and 35" tires, he is losing a fair amount of torque through the drivetrain. The larger diameter tire is the same as having a longer lever attached to the axle, that the engine is trying to fight against. By putting in lower gears, its giving the engine more leverage to fight against the larger diameter tire.

This is the reason you have much much more torque in low range than in high range. Although because a regular engine has a limited operating range, you need to go with gearing which will give us a compromise between wheel speed and available torque.

COSWORTH

Torque will multiply, but RPM will divide HP=TQxRPM/5250


Gear ratio has never made a difference on any of the vehicles i have chassis dynoed...

arkain04

Gearing only allows you to reach that peak horsepower in a quicker time frame.
The only way to increase rear wheel horsepower is lessen drivetrain loses ie. lightwieght flywheel-driveshafts or simply increasing engine internals for more horsepower..

Schantin

That's a great torque curve. , especially since your rig was tested on a Mustang dyno. Those historically give "low" results.

Screamin Lizard Customs

Looking good Mike.


How's everything?

Gerry

Ronson

I'm impressed by the torque # this is what you feel when you drive. I have my Hemi and tranny but had to put it on hold for now. I blame Obama

jmelgin

Thanks for all of the kind words. The motor/tranny setup is awesome. Gerry and the boys at SLC did a super job. My only issue is that the exhaust is a bit too aggressive for my taste (probably because I'm and old fart). If anyone is hesitating to pull the trigger on this conversion, just go for it. You'll not regret it!