For the engine gurus.

[bazza2541]

What are the differences between the 2.8 and the 3.1?
Are any parts interchangable?

[geeves]

Only minor parts can be swapped ie oil pump and filter from later 4jb1 into 4jg2 timing belt on some 4jb1 is same as 4jg2 manifolds thats all

[bazza2541]

I heard the push rods can be swapped over?

[geeves]

true although the 3.1 ones are slightly thicker This could cause oil return problems in theory but hasnt in practice yet

[Drift]

Yup push rods fit, slightly thicker





But plenty of room in the channels (an old good head)


One concern is if they are stronger and the belt or bearings go they could cause valve damage, I was lucky and just bent 2.8 push rods, but change belts and pulleys in good time and it should not be an issue.

Starter, alternator, turbo, power steering pump, water pump and most ancillaries will fit.

An oil pump as reference

[bazza2541]

Would the 3.1 crank swap accross?
If so would it give a decent increase?

[geeves]

5mm longer stroke. I think the pistons will be pushing the head off the block.

[bazza2541]

5mm longer stroke. I think the pistons will be pushing the head off the block.

How so? IIRC all the 4J blocks are the same size?
I do know that swapping cranks to make stroker motors is quite common in petrol engines. Of course if no-one has hgeard of it done on a 4J it probably means that it won't work.

Would the 4jb1 benefit from other tuning methods? Porting and polishing? or larger valves?

[geeves]

It has been done with huge increases but no details on how much you can port things. Just wind the turbo up to 15 then advance the timing to just before it knocks and increase the fuel to just before it smokes. Mudlark had his wagon dynoed with these mods at 110kw and it was still reliable

[bazza2541]

110kw.....by my reckoning thats about 150bhp, that'd be fantastic.
Right now I am at 117bhp (86kw) with standard boost, pump and timing. Is Mudlark a member on here? Is there a build thread?
Many thanks.

[98Rodeo]

hi bazza, what have you done to get that much power without upping boost and fuel?

[bazza2541]

I have fitted a turbo, intake and exhaust off a 3.0 and a FMIC off a TD5.
Few pics.
Click to enlarge.