Which Cat 3406 should I start with for maximum HP

If your wanting over 800hp your best bet would be to get a 2WS, 1MM, 6NZ, 7CZ or MBN. MBN only if you want to do a rebuild before you put it in as the pistons, cam and injectors wouldn't be as good as the previous prefixes. They're all 70pin ecms.

You could probably go with a 1LW as well but their known for breaking the cranks. Although if they have high mileage good chance the crank won't break. Normally if they're gonna break it will be before a million miles on the crank.

If you want over 800hp stay away from a 5EK as they are prone to cracking the block over 800hp. Can't remember if the 6TS had solved that issue or not... I know the 1LW definitely has a stronger block than 5EK

 

What could be expected if the 250 was turbo charged? I'm guessing it would be good for another 150 hp.

How many rpms is the cummings running at 55?

 

Its easy to make power with a b (turn up the pump and new nozzles) but If your aiming for over 1000hp eventually I think it would be cheaper with an e. You'll need more than a ecm program to make 800hp.

5EK, 6TS, 1LW and 5DS are all 40pin 3406Es easy to make 800hp with. 2WS, 1MM, 6NZ, 7CZ and MBN are all 70pin ecms a set of injectors, turbo and ecm program and easily over 800hp.

 

If you start with a good base engine, you will need a cam, turbo, injectors, and a ecm upgrade. Then you would have to upgrade most of your driveline in that truck to handle the power and torque.

 

You're not gonna get 800hp out of anything for very long without getting a suitable turbo. 800hp could to obtained with a 5EK or 6TS with a higher factory rating (475 or 550) as most of those engines all have bigger injectors. With the right file in the ecm you could get away with 800hp without the cost of buying injectors.