Ok well i guess i am interested to see what other people have experienced tuning a td42.
I have tuned motorbikes and cars but am fairly new to diesel turbo tuning.
From what i can gather their needs to be some sort of balance.
Really after info on what kind of boost levels and rpm combo's work best.
And at what point do you lose power from exhaust back pressures due to to much boost etc
If you have a standard injector pump then that will be a limiting factor. You also need to consider the efficiency map of the turbo to determine the safe maximum boost pressure. If you push a turbo out of its efficiency range you may get more boost but the temperature of the compressed air will be too high to be beneficial, especially without an intercooler. You will need to contact the turbo manufacture to get a copy of the turbo map.
You should really start with basic tune, ie adjust valve clearences, new injectors, pump timing.
Then I would start with 14Psi boost and gradually wind up the fuel until you see between 500 and 550c-post turbo peak sustained EGT (up a long hill, towing a heavy trailer if you have one - you want to put the engine under maximum load). As you wind up the fuel you will need to wind down the idle, once you run out of idle adjustment the pump is maxed out. The next step is to get the pump modified with a larger plunger and a boost compensator, at this point you really need to be getting the vehicle professionally dyno tuned as well.
I wouldn't go over 14Psi without an intercooler and 3" exhaust.
Note, tuning diesels by EGT's is a guide only, mixtures should ideally be set using a mixture meter.
Boost v RPM, you want the boost to come on as early as possible.
Tony
Going to have to find a bigger hill i went up one today that use to labour it up bad and it cruised up it only reaching 450 degrees max pre turbo.