Transaxle/Transmission Ratings, Torque or Horsepower Options

[Brian Mifsud]

Something discussed long ago way way back to "Porschephiles"...

In many posts, I've seen people rate transmissions/ transaxles by maximum horsepower. I believe that this is misleading and incorrect. As far as I know, gear and shaft diameter as well as gear tooth size (thickness of gear) within a transmission dictates how much torque one can manage from input to output (assuming decent alloys are used in gearmaking). Too much torque fed into a transmission, and shafts can deflect, or gear teeth can shear, and either way, we have a failure.

HP = Torque x RPM X (some constant I forget)

Let's say I have 2 engines, both rated at 100hp max. One is a slow reving 250CU V-6, and the other is a 1000CC superbike engine. The 250 CU engine will put out roughly 200+ -odd ft-lbs peak, and the superbike engine will pretty well max out at ~60 ft-lbs (BTW, after years of reading the spec sheets in car and driver, I've noticed that most engines put out ROUGHLY 1 ft-lb torque per cubic inch regardless of style).

Both engines will get to the 100HP rating, but at different torques input into the transaxle.

Of course, if I run a transaxle at very high rpm, I will get lot's of heat through bearing and gear friction. Eventually, it will fail, but I believe for different reasons depending if it was a low torque/high RPM engine feeding it, or a low RPM high torque plant.

My understanding was that the 901 was dependable for 200-odd ft-lbs. Of course, the factory will probably go one step further and rate them at a certain RPM to include the heat buildup from speed.

Well, anyhow, I believe this to be true. Of course you'll reply if you know better than I and I humbly admit I don't know it all.

Also, does anyone have the actual specs from the factory for the 901 and it's varients?

Thanks

Brian

[Brian Mifsud]

Have any of you V-8 guys done the research and found out what the 901 was rated at in foot-lbs? Or has it been more a case of break and replace?

Thanks