
Originally Posted by
nissannewby
1. The most you want to do is an exhaust side high flow on a HT18. I am currently in the progress of upgrading to a TD05 18G and will show results once done. I have had the standard setup tuned to a respectable 142hp and towing a 3 tonne trailer it will do about 17-18l/100. The standard turbos spool nice and early but run out of puff pretty quick. Ben-e-boy has just finsihed some modification on his TD42 and is running a TD05 16G from the dts kits with very good results.
2. I have only used TD05 turbos as they are a journal bearing turbo and the garret ball bearing turbos reliability is sometimes questionable. The journal bearings can take a lot more abuse before failing and a minor rebuild is cheap compared to that of a ball bearing unit.
3. Like I said I have just dynoed mine and it returned 142hp at the wheels. This is on a factory intercooled turbo motor though. I have removed the EGR and vent the crank case breather to atmospher, run a 3" mandrel bent exhaust with dump pipe. The bigger the exhaust the quciker the gases can escape allowing your turbo to work better.
4. Without an intercooler I wouldnt exceed 14 psi. When you compress air it heats up and being that the HT18 is on the smaller side anything beyond this it just makes to much heat (air thins out) and EGT's will start to become an issue. With a intercooler I wouldnt go much further than 16 as the turbo will be out of its efficiency range (HT18).
5. 3" from the turbo back. This will improve response and help lower EGT's slighty. It is the most common size and is cheap enough.
6. With a HT18 best value for money would be an exhasut side high flow, 3" exhaust from turbo back and an intercooler setup. Follow this up with a tune and you will be very satisfied.
My standard factory turbo setup with intercooler with my tune will pull our big heavy trailer without to much drama in a 100k zone and up an incline I havent had to go below 4th gear. And I hear what your saying about the standard setup they are dismal power and torwue wise. Mine without any load normally sits around the 13/100 mark.