Thread: Defender 4BD1T Conversion

Originally Posted by C H T

Justin C suggested that I should put up a post about my Defender to which I recently fitted an Isuzu 4BD1T (very late Factoryturbo). The conversion was carried out by British Off Road who did an excellent job. The engine instalation looks and drives like a first class factory instalation. The engine was sourced from DNA truck parts in Minto - highly recomended also - and great to deal with.
1. The engine instalation.
I used a very rusty Isuzu County as the donor vehicle for all the Landrover specific parts - Bell housing (LT85), sandwhich plate, starter motor, aircleaner brackets, engine mounts (engine and chassis), radiator, header tank etc. I managed to obtain the Landrover Australia spacer to go between the twin oil filter hosing and the engine block, and made a spacer to fit between the oil line and the oil cooler - (gives clearance for the front tail shaft. The county chassis engine mounts were welded to the Def chassis in the relevant position. A brand new genuine LR Donaldson aircleaner housing was sourced from ULR in Melbourne. I retained the factory 4BD1T thermostat housing, and modified the Turbo cross over pipe. We had to remove the steel underbonnet stiffeners and replaced them with aluminium flat bar in order to give clearance.
2. Gearbox.
We used the R380 that was behind the 300 Tdi - it has the larger layshaft bearings - mated to an LT85 bell housing. apart from some initial alignment problems - see below - the installation has run over 11000kms now trouble free. A 1.2:1 Disco transfer case was fitted, which with the R380 and 235/85 R 16s gives 2255 rpm at 100 kph and just over 2400 at 110. We have used a 6x6 clutch pressure plate and a custom soft centre clutch from NPC in Brisbane (great service) - no gearbox rattle at idle (upped to 800rpm).
3. Problems
1. Bell housing/gearbox alignment.
KLR did the initial mods to the bell housing, but didn't quite get the alignment right (about 1.5mm out). Brad very quickly offered to rectify the problem at their expense but time constraints memant that BOR sorted the problem in house. No complaints from me about KLR.
2. Rear main seal leaking. There was a very small groove in the seal surface on the crank shaft. After three changes of seal in as many months we fitted an Isuzu factory wear ring (like a very thich speedi sleave) and over size seal which seams to have fixed the problem completely.
3. Oil out of the engine breather.
The engine was poking a fair amount of oil out of the engine breather. I cut the top off the oil separator and forind the the small "mushroom valve" was well past its use by date allowing significant quantities of oil to surge up the oil drain line connected to the sump. The valve was repalced with an identical one from a Holly Carb kit. Problem solved.
4. Was it worth it?
Absolutely!!!! the vehicle does a lot of bush/remote area/long distance work fully loaded summer and winter, and while the 300 Tdi did a fantastic job, it simply wasn't big enough and therefore was working hard all the time. The Isuzu has transformed the vehicle it is quieter and smpoother than the 300 Tdi - yes really!, noticeably faster on the hills and when towing, and much better in the bush - particularly in very steep country.
5. Before I forget.
Boost increased to 11psi with the fuel screw wound out just under half a turn (approx) Fuel economy so far 18.5 to 23.86 mpg.

As for the rest of the vehicle it was the very last 300 Tdi 110 wagon sold in Australia according to LR, Maxi drives front and rear, aux fuel, ARB B/bar and warn 10000lb winch etc etc.

Christopher

Thanks for the insight to all Christopher, And well done. It is a fantastic engine/ box for a 110. Have you thought of 255/85 tyres? At about 33 inches they give great salisbury clearance, excellent off road and that engine will easily push them.
Makes me want to buy a 110 again now...

JC

PS The conversion is fully complianced with an engineers certificate. All very straight forward.

That sounds like a very nice Defender


Any pictures?

Justin I will be looking at tyre sizes when the time comes - the STTs are still less than half worn and performing brilliantly - Dobbo I am afraid no pictures at present but will see what I can do.

Christopher.

Nice writeup. Being a very late model motor, do you have the non-wastegated turbo?

Originally Posted by Dougal

Nice writeup. Being a very late model motor, do you have the non-wastegated turbo?

Dougal
No the turbo is a wastegated Garrett. I understand that the order of turbo fitment to the 4BD1T is as follows:
1. Wastegated IHI. (not watercooled). Early 4BD1Ts including Australian army versions fitted to the 6 wheel-drives.
2. Non-wastegated watercooled Garrett. Later 4BD1Ts.
3 Wastegated watercooled Garrett as per my engine. Very late 4BD1Ts - mid nineteen nineties - mine is about 94 vvintage.

Christopher

Originally Posted by C H T

Dougal
No the turbo is a wastegated Garrett. I understand that the order of turbo fitment to the 4BD1T is as follows:
1. Wastegated IHI. (not watercooled). Early 4BD1Ts including Australian army versions fitted to the 6 wheel-drives.
2. Non-wastegated watercooled Garrett. Later 4BD1Ts.
3 Wastegated watercooled Garrett as per my engine. Very late 4BD1Ts - mid nineteen nineties - mine is about 94 vvintage.

Christopher

Ahh very interesting. I have a 4BD2T turbo (in the parts bin) which is non-wastegated so assumed the last of the 1's would have had that too.

I'll wait patiently for pictures.

Originally Posted by Dougal

Ahh very interesting. I have a 4BD2T turbo (in the parts bin) which is non-wastegated so assumed the last of the 1's would have had that too.

I'll wait patiently for pictures.

I'm afraid the pictures may have to wait until the new year - no suitable camera available to take them yet!