Thread: 4bd1 to 4bd1t

HI,
I would go the truck turbo engine if price isn't a problem. Turboing your curent engine will be cheaper and less hassle fitting of the bellhousing to gearbox etc. What type of turbo conversion are you after? A full blown fire breathing dragon or simply a couple extra ponies and forget the intercooler type conversion? There's so many ways to go. The search engine on this site is your friend as many many isuzu's have been treated to various different turbo systems and all bring a big smile on the owners dial.

Cheers,
Brian.

Also ask yourself 'what do you want it to do' - the vehicle that is..?

There's a fair expense in fitting a turbo, so with your answer to the (above) question, is it worth it.

I'm not trying be all Zen, but you may find tipping in 50% of the vehicle value in modifications will never be recovered, nor realised as an advantage. Assuming a 4BD1T engine is around 6k.


Matt.

Thanks for the thoughts. The truck is a keeper so not worried about resale. Always liked something a bit different and haven't seen any ex mil with the turbo conversion. Has anyone driven both with and without? Always liking for more ponies but don't expect to be doing any wheel stands anytime soon either.

Turbocharged 4BD1s have stood the test of time in Land Rovers, with some lasting for as long as 500,000 kms between rebuilds. "Light duty" industrial diesels such as the 4BD1 have been seriously over-engineered & take the occasional abuse we may put them through very well.

That said, the main differences between an 89 4BD1 and a 91 4BD1T engines (as far as I recall) are the turbo block comes with:

1.) Case hardened crankshaft to improve wear & reduce friction. The case hardening process (nitriding / also known by its trade name Tufftriding) creates a very thin layer of super hard steel. The crankshaft is known to last several rebuilds, but also means it can't be machined in the unlikely event of scoring.
2.) Oil squirters fitted under pistons for better cooling / lubrication
3.) High flow oil pump (to feed oil squirters and turbo)
4.) Twin oil filter setup potentially allowing for longer intervals between oil changes (many N/A trucks came with this as well)
5.) Potentially a boost compensated fuel pump that allows reduced off boost fuelling
6.) Turbo oil drain integrated into the casting, although some late 4BD1s reportedly have the same provision



Early on in the production, only the 4BD1Ts came with alfin pistons fitted, but after 88 I think, Isuzu started fitting them to naturally aspirated engines as well. BTW, "alfin" stands for Aluminium Ferrous INsert (I think), so aluminium piston with cast iron inserts around piston ring grooves for better wear characteristics, Your 89 4BD1 would likely already be fitted with them.

If it's worth it I think depends on your preferences. Oil squirters allow slightly higher "safe" EGTs, meaning you can tune the engine to run a slightly richer mixture under max power conditions, but that's only if you're wanting to really push the limits.

Oil squirters (brass tubes pointing to the underside of the piston) look like this BTW:



HTH

Bojan

I think there is also a difference in the IP, or at least the tuning of the IP as several on the site (myself included) who have turbo'd their NA engines find a surge / stutter at around 2700. The more you turn out your fuel screw the more noticeable it is.

There is no need to fit a factory turbo engine unless you are going for all out performance, but if you have one laying around I'd use it to get around the stutter / surge.

Originally Posted by obelixxx01

Thanks for the thoughts. The truck is a keeper so not worried about resale. Always liked something a bit different and haven't seen any ex mil with the turbo conversion. Has anyone driven both with and without? Always liking for more ponies but don't expect to be doing any wheel stands anytime soon either.

Mine is a civvy 110, but I drove it for a few years without a turbo before fitting it. Night and Day.

Thanks guys for all the info. Seems I have some thinking to do. One more question though. I am of the assumption that to so an engine change over would be a bolt out bolt in event? Does anyone know of any possible kids/adapters that may be required?

Originally Posted by obelixxx01

Thanks guys for all the info. Seems I have some thinking to do. One more question though. I am of the assumption that to so an engine change over would be a bolt out bolt in event? Does anyone know of any possible kids/adapters that may be required?

Major things like engine mounts will swap straight from one block to the other, also flywheel housing, bell housing etc. You might come across some minor differences like the throttle linkage.

Cheers, Murray