how to calculate torque specs in 4-lo/ double lo etc
 

a stock 3.0 for example is 150 hp at 3000 rpm and 180 ft lb of tourqe. how would i figure out what the tourqe is say in 4-lo with a transfer case having 2.57 gear ratio, or even better dual cases with 4.7s in the rear case. i know how to calculate crawl ratio but was curious if its possible to do the same with tourque?? Thanks

not really possible because the factory toque values are giving at the crank not the tires. I am sure there is some sort of equation you can come up with if you knew exactly what the proportional drivetrain losses are in different gears and such, but regardless what gear your in 4lo/4hi the engine will still get 150 HP @ 3000 rpm.

ya i know horsepower wouldnt change. if just stock 4-cyl case with 2:28 t/case was in guaged (4-lo) i would think you would multiply 180 x 2.28 wich equals 410 lb i dont know if thats a correct calulation and how to figures lower ring and pinion, dual cases etc

Yep, for a rough approximation, just multiply the gear ratios of the trans, t-case(s) and ring/pinion gear to get the torque out to the wheels. Unlikely you'll see 100% of the peak engine torque in normal use.