Yobbo wrote:So just to confirm, without an intercooler, the standard turbo will be fine at that level of boost?
I know you have to adjust fuelling so it doesn't end up too lean
The standard turbo is fine without an intercooler (up to 14psi, with occasional excursions to 17 absolute maximum)- the engine, on the other hand, won't appreciate 17 un-cooled psi. I'd stick to 12-14psi without an intercooler.
Diesels don't care about lean mixtures, in fact a lean mixture will keep your EGTs down. Rich mixtures (below 16:1) kill diesels.
If it smokes when you stomp the accelerator, IE before the turbo spools up, try winding the boost compensator star wheel *up* (higher/more pressure on the spring) one turn and see what happens. Check out this thread: viewtopic.php?f=94&t=18908&start=15
(it's specifically for tuning a Hyundai engine when installed in a Delica, but if you ignore the bit about removing adjusters and aligning the accelerator lever, it's a generic how-to-tune-a-4D56 guide.)
Yobbo wrote:presumably it'll be fine to install a T for the boost gauge in line with one of the small boost hoses that goes to the compressor housing?
Yup. I'd tee into the one that goes to the injection pump, so you can make the junction close to the pump where it's easy to get at without having to remove the drivers seat engine cover.
Yobbo wrote:In regards to tuning I can't quite justify the outlay for a wideband AFR at the moment but have spotted cheap probes and gauges that will work in the normative ratios though don't know if it'll be good enough.
Don't bother. The AFR ratio for a well-tuned diesel is 18:1 up to 99:1. A narrowband sensor (or a wideband that doesn't have a diesel mode) is useless. You can get 90% of the way there by watching your smoke and EGTs. The thread above has a description of what to adjust to get the EGTs the way you like them.
Nothing says "poor workmanship" more than wrinkles in the duct tape.