[Christ]

You'll want to monitor your EGT's more than anything... I think at cruise it should be around 600degF for maximum efficiency, I think I read that somewhere. (Maybe it was my Adele's manual...)

Also, your intake charge should be cold for highest efficiency, so if you can run the intake piping of the turbo to a cooler place, it may be of benefit to you.

Basically, with a diesel engine, you want to keep the block warm, but keep the intake and exhaust cool. The idea is that the colder intake charge will put more air around the same amount of fuel, increasing the chance that it will all burn, and the combustion's heat should be dissipated for the most part due to thermal expansion before it's put out the exhaust. IF this is not the case, you're wasting efficiency.

If you can figure out how, you can adjust your injection timing for better efficiency in the ranges you'll normally be operating in. The tighter you can keep your RPM range, the better, because you can dial in your engine for the way you're going to drive. HyperTech can help you with this.