Thread: Isuzu Engine Swops for Dummies

At the moment I'm at a bit of an impasse - waiting for the Defender to get here, and waiting for JC's gearbox to make it up from Tassie, so time to give the engine a once over, and to order in everything I need. for now though, using Vern's Isuzu parts to get everything mocked up until my own come in.


Ordering the Isuzu bits and pieces has been interesting - for the most part I've been ordering straight from Patterson Cheney Trucks in Dandenong as their prices seem to be the best, even in comparison to some of the truck wreckers yards, though I've learned that as soon as I mention "Isuzu" and "Land Rover" either their eyes glaze over, or I get the same face that I assume is usually reserved for people who admit to killing small animals or homeless people in their spare time. But anyhow, they are ordering in a shiny new exhaust manifold for me, as it's more suited, size and position wise, to the turbo I plan to run.

A word to those who don't already know - the turbo manifold comes in two flavours:

1984-1987 non-watercooled manifold (P/N 8-94119292-6)
1988 onward water cooled turbo manifold (P/N 8-94366247-0)

The earlier manifold has the flange slung horizontally underneath, while the later manifold has the flange set at about 30 degrees off vertical. for the purposes of this engine swap we'll be using the later manifold, as it gives a bit more leeway as to what turbo can be used in the limited space underneath the defender bonnet.

Images shamelessly stolen from the internet





The turbo of choice is a GT2260v variable geometry turbo, from a 3.0l Iveco Daily van, namely because others have run it with the 4BD1 without issue, it will give a good combination of early boost but not be strangled on the highway, but more importantly, Vern had one that was sitting idle on the shelf that was in need of a rebuild, and he's more than happy to experiment on my engine before bolting one onto his own

However, the turbo has a T2 flange, and the manifold a T3, so in order to mate the two, a T2/T3 flange adapter has to be made up. A few people have made these up already - you can see the steps below.



Manifold with T3 flange:



First part of the adapter bolted up:



Second part of the adapter bolted up:



Manifold studs bolted up to take the turbine housing. Only modifications you need to make is to drill out the threads in the turbine housing to take the studs.



Turbine housing bolted up. For now it's just a dry fit - will be using high temperature copper gasket cement on all mating surfaces later.




For anyone curious as to how a variable geometry turbo actually works (I know I was), well here you go. The principle is simple - the optimum A/R ratio of the turbo at low engine speeds is very different from that at high engine speeds. If the A/R ratio is too large, the turbo will fail to create boost at low speeds; if the A/R ratio is too small, the turbo will choke the engine at high speeds. VGT turbos get around this by shifting the angle of a ring of vanes inside the exhaust housing depending on engine requirements. which change the angle of exhaust gas into the turbine. Essentially it's a variable A/R ratio housing.



Vanes open:



Vanes closed:



Changing the position of the outer ring adjusts the pitch of all vanes in the turbo.



The plan is to control the VNT actuator through a Dawes valve, as shown.



This turbo wasn't in the best of shape, so it was a good excuse to overhaul it. SteveG can at least take solace in the fact that I learned from his experience that the compressor spindle is reverse threaded, and thankfully nothing went snap as I disassembled it. The damage is pretty obvious - old parts on top show a worn bearing, a chewed up turbine wheel, a chewed up washer seal (pieces of which probably chewed up the turbine), and a number of bent and seized vanes. This thing obviously ran low on oil at some stage judging by the scorching and discolouration of the turbine shaft.



I ended up rebuilding the turbo while bolted to the engine, because the standard layout didn't really suit the plumbing I wanted to run, and the actuator ring needs to be set up to line up with the VNT lever (you can see the notch for the arm in the 7 o'clock position). There's a small locating dowel in the turbine housing that will need to be redrilled once everything is lined up.





Compressor housing going back together....






Vern scratching head and coming to terms with "righty - loosy, lefty - tighty".....



Side view of the turbo and spacers. As you can see, it brings the turbo out from the engine by about an inch, but only raises the overall height marginally.



As you can see, the orientation of the turbo is much more suited to what we want to do in terms of running intercooler hoses, etc. The turbo cartridge also happens to line up perfectly with Garrett's recommendations of having the water ports at an angle of approximately 20° from the horizontal





Exhaust outlet tack welded in place for now. Once the sump is cut and shut, the exhaust will run down behind the alternator and in between the chassis rail and the engine, same as a 300tdi. For safety's sake, will run a heatshield between the alternator and exhaust later.

Just noticed your "location" Mike. hehe