M813 855 to 8.3 Cummins swap

[EricTheHoly]

I have a m813 I pulled the engine and have a 8.3 I’m going to be swapping in I’m looking to make around 600hp and 15-2000trq with the 8.3. What do you guys recommend for building the engine? Also any ideas on different gears I might have to put into the truck? Thanks

 

[simp5782]

I have a m813 I pulled the engine and have a 8.3 I’m going to be swapping in I’m looking to make around 600hp and 15-2000trq with the 8.3. What do you guys recommend for building the engine? Also any ideas on different gears I might have to put into the truck? Thanks

It'll last a few months at that power rating

There is a 8.3l power thread in the hot rod section.

Gear ratios for the 5 ton Rockwell range from 4.10 to 11.26. Finding them isn't easy though.

Sell the 8.3 and nhc250 and buy a big cam and a 10spd and go from there. The 8.3l is a few ft shorter than a 855 so you will have to move a cross member in the front or the rear mounts which will move the shifter location. For the big cam and 10spd you would need new engine mounting for the sae 1 housing setup

 

[Dirt71]