how much power can a nv4500 handle with a good clutch? and the fixed 5th gear nut? thanks

 

To be honest with you, I don't know, BUT in all my reading I have never seen or heard of anybody having to upgrade or modify the NV4500 for power except for the 5th gear and there are a lot of trucks out there pushing big power. Same with the transfer case.

 

The imput shaft is a weak point on a NV4500. they can be upgraded with one of south bends 1.375" imput shat for the five speed (the stock one is 1.25). this is the same size as the 6 speeds.

 

I dynoed 611 TQ to the rear wheels and replace my 4500 about every 100k miles. I have yet to break an input shaft, but the internals just aren't meant for that much torque and constant towing. I remember reading somewhere that it was designed for about 450 lbs of TQ which would make sense. Stock, my engine was rated at 440 TQ at the flywheel.

 

The stock CLUTCH won't handle much ovet 275 HP so it neeeds ungraded with HP mods.

 

The tranny is rated for 460 ft-lbs, but as we know, these things are built tougher than they are rated for.

Only issue I've had was losing 5th gear in my dually, but that is a design flaw, not a failure due to power.