Thought that since i have often looked for info on this
forum i should post my outcome...
1990 GQ (Jap import Nissan Safari with small 75ltr
fuel tank)
At 360,000km truck was getting tired (I was getting tired of truck) and not using common sense I decided to make some mods. I decided to build my own Turbo system as the prices for Aussie kits in NZ seemed too high to justify. Unfortunately being
young, an engineer (although a desk job type) and having lots of mates to give suggestions I ended up going a little over the top on the set-up. Basically after lots of internet reading and learning to read turbo compressor maps I opted for a new Mitsubishi TD05-16G turbo. Next I slowly and painfully built an individual cylinder feed exhaust manifold from schedule 40 pipe and bends. I went for an upward mounted turbo which sits 2” under the bonnet insulation. From here I built a heavy 3” schedule 40 elbow out of the turbo with a separate 2” s/s waste
gate outlet which blends together into a handmade 3” stainless exhaust (tig welded from mandrel bent pipe). (Pyrometer was fitted into elbow at exit of turbo) The exhaust was a mission but made easier with the use of a mates hoist. I built it in 3 sections and opted for a straight through high flow 3” muffler and exit behind the rear left tyre. Back up front I put in a 3” thick Medium RacePro front mounted intercooler after ditching the aircon. Piping for this was 2.5” alloy with some silicone fittings. I managed to get a nice unrestrictive arrangement after moving a few things around under the bonnet. As a final overkill I pulled the head off for a tickle and ended up spending 13hrs porting, valve shaping and contouring the inlet chambers. I think this is what gives my truck the edge. After winding up the
fuel the clutch lasted 2 gear changes on the first test drive – bugger. After fitting a custom made heavy ceramic/fibre clutch it was time to set the
fuel. Decided to get some new injectors apparently rated for higher flow as the old ones were stuffed. Original radiator was mush so sourced a 3-core high capacity one from Aussie through a mate. Currently been running peak boost of only 9PSI with EGT at 110km/hr and flat road sitting at 160 C. Peak temps under high load (5th gear up steap hills at 120km/h) are pushing over 500 C although I drive to the pyro and just shift down to 4th. Truck is so different from original to drive that I haven’t done anything with boost yet but that’s on the cards.
Fuel economy in city is worse at 14L/100km (but that’s currently due to driving style) and open road is similar at 11.5L/100km @ 100-120km/h. Towing a small boat but at pace seems to use less
fuel than before but I get there far faster. Currently starts boosting over 5PSI from 1400RPM and wheel spins in 1st, 2nd and 3rd gear. If it’s a bit wet can get it spinning in 4th as
well. OK that’s not what a part time 4wd is for but its been fun learning to drift it in 4th on a typical drizzly NZ winter day on our windy back roads…
I have a theory that I plan to try ie: increase boost to 12-13PSI, reduce peak
fuel rate slightly and see how it goes and if
fuel useage drops at all. As a note the approach I took was to maximise thermal efficiency, air flow etc to get the most without having probs with high temps.
Water temp needle does not move above ¼ now when towing my old mans 2.5 tonne boat under heavy load. Previously would go over ½ and fan would kick in and we would be going sooo much slower!