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how do they compare as a motor. Everything I can find online suggests an industrial motor

geeves wrote:how do they compare as a motor. Everything I can find online suggests an industrial motor

so is the 4jb1,

Apparently a few 4jb1's and 4jg2's have benefited from this set up done by one mechanic here,my friends shop has sold more then 10 sets to this person,so this guy must know the how things are put together .

i dropped by the parts shop today to take some photos but my friend was out so some time next week i'll drop by again.

FINALLY!!!! got the pics and measurements, bore is 105mm, 3mm bigger then the 4jb1, bowl shape is a late model direct injection type so nozzle has to be changed...and the best thing is that the pin sits 2.5 mm higher meaning the 4jg1 piston is 2.5 mm lower then the 4jb1 , so can use the 4jg2 crank which has a stroke of 107 as compared to 102 on the 4jb1...do the maths 107mm-102mm = 5mm /2 = 2.5mm so the off set suits the 4jb1 block....looks like a plug and play aside from reboring the cylinder...doing a conversion now so will update from time to time...

geeves wrote:Ive heard of 4jg1 parts but never ever seen a reference to a 4jg1 engine. Is this a mythical beast of the same nature as a 4.88 diff?


Early versions of Ingersoll Rand 185 cfm portable air compressors runned with 4JG1 engine (newer ones comes with John Deere)...Also we can find these engines in some boats, generators, bobcats, mini excavators (kubota)....although I never seen turboed applications.

superturbocompound wrote:



FINALLY!!!! got the pics and measurements, bore is 105mm, 3mm bigger then the 4jb1, bowl shape is a late model direct injection type so nozzle has to be changed...and the best thing is that the pin sits 2.5 mm higher meaning the 4jg1 piston is 2.5 mm lower then the 4jb1 , so can use the 4jg2 crank which has a stroke of 107 as compared to 102 on the 4jb1...do the maths 107mm-102mm = 5mm /2 = 2.5mm so the off set suits the 4jb1 block....looks like a plug and play aside from reboring the cylinder...doing a conversion now so will update from time to time...


As always Conrad doing brilliant projects, hurray!! ....cannot see the pics though...

hmmm... abit confusing here, the 4jg2 blocks is taller by 4mm....the pistons of the 4jg2 is identical in height to the 4jg1...which is 2.5mm lower then the 4jb1...maybe the rods are different? pistons protrusion are almost identical...any ideas???

Why not use the 4jg2 block, crank, rods, 4jh pistons and 4jg1head....if you can find one that is!

reason not to use another engine block is when an engine is changed here, the car loses its 'GREEN' status hence 50% off the road tax...

progress report:-


the 4jg2 crank is in with its extra 5mm stroke....

and this is how much it protrudes out of the engine block...so this configure is with the 4jb1 rods and pistons(4jb1 sits 2.5mm higher)...

there is about 3mm piston protrusion...2.5mm lower if it were the 4jg2 piston...so i think this will work....cranks spins freely not hitting anything (for the moment, dunno what happens when fully assembled)

superturbocompound wrote:reason not to use another engine block is when an engine is changed here, the car loses its 'GREEN' status hence 50% off the road tax...
We don't have that kind of road tax system here in Aus. If tax wasn't an issue would using the 4jg2 block be easier? I didn't quite follow the piston differences between the 4jg2 and 4jg1.

progress report:-
there is about 3mm piston protrusion...2.5mm lower if it were the 4jg2 piston...so i think this will work....cranks spins freely not hitting anything (for the moment, dunno what happens when fully assembled)

So is the 4jg1 piston going to protrude .5 m.m. out the top of the block?
Thanks for updating, this is an interesting experiment!

Roderunner wrote: I didn't quite follow the piston differences between the 4jg2 and 4jg1.
the 4jg2 and 4jg1 are identical in height...

Roderunner wrote:So is the 4jg1 piston going to protrude .5 m.m. out the top of the block?

its about that...was going to use a dial gauge but the battery was flat(digital)...

from what i see....to convert the 4jg2 to a direct injection...head change , fuel pump nozzle(maybe fuel pump), head gasket(4jh1) pistons...(off hand)