On my 90 idi I have water in a drivers side cylinder. Hopefully it's just a head gasket. Since the motor has about 180k on it I'm pondering a complete over-haul.

My question is what do I need to overhaul it to a '94 idi turbo specs? And is it worth it?

I would like to add a turbo to it when the checkbook allows and I understand that the 94's were built heavier to compensate for the added stresses.

All I know of now is that the pistons are know as the "big pin" ones.

Finally, Is there any resource that can take me through the overhaul process better then my Chilton manual?

Thank so much, I appreciate your input!

 

The main difference is the valves and valve seats are made out of Inconnel.
The pistons are hypereutectic which is a high heat resistant aluminum, silica and several other material alloy in all the Navistar diesels, but the turbo ones have bigger wrist pins.

The compression is actually a little lower on the turbo motors as well to make room for all that extra air the turbo blows in there.

I spoke with a tech support guy at ATS about the different components and were they worth the money difference as the Inconnel valves are high dollar items.

His reply was that they had thousands of their turbo's out there on completely stock NA 6.9 and 7.3 IDI motors running boat loads of miles without problems.

Most of the work you will need done other than disassembly and reassembly will have to be done by a machine shop. I would talk to several different shops and get input from them on how they feel. I would also talk to several garages to see who they get to do their machine work on diesel motors to figure out which machine shops to talk to first.

 

If the compression ratio is lower it isn't worth it, the power will go down and it will start a little harder when cold. There's nothing wrong with turbo-ing a NA engine.