transmissson choices

Best choice is to stay above a 189, 209 would be best

 

Just about every Eaton tranny designed for the class 8 market, except the lower cost fleet varieties, will handle 600 hp and 2050 lb torque. But not if driven by an idiot. Keep in mind Eaton, Meritor, etc will publish lower ratings than what the tranny will actually do. It is all about legal issues. I have seen trucks that have been spiked to 700 or even 800 hp and putting down an easy 2200 lb of torque using standard 13, 15, or 18 spd trannies. It is all about the operator and how he uses that power correctly. It probably would not be my first choice to use a non specialized tranny in that application, but it is safe to do so in the right hands.

 

What Cowpie said is the truth. You should have temperature gauges on the transmission and differentials. If you are smart enough to drive by the temperatures, about any combination will work.

Back in the day, I ran an old cat with the fuel turned up, 13-speed double overdrive, 4.33 rears and 24.5 rubber. It figured out around 102 MPH and ran 98 MPH on the dyno at the Cheyenne Cat house. I always ran over 102,000 pounds eastbound.

You could cook the turbo or any box on the truck if you wanted. On hot days and heavy loads you just drove by the temperatures. I never had a single problem with anything related to ratings, heat or load and 75 was taking it easy.