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Making a 4JG2-T into a 4JG1-T with common parts

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Making a 4JG2-T into a 4JG1-T with common parts

Postby gomulletgo » Sun Sep 10, 2017 2:31 pm

Hey guys,

I didn't want to hijack this thread: viewtopic.php?f=19&t=4727 ..... is it possible to fix the broken photobucket links by editing the posts and uploading the photos directly to clubisuzu?

I found rabidrabbit001 by chance on a facebook group, he was very helpful with info on how he modified his 4JG2-T into a 4JG1-T using a 4JG1 head etc. He also gave me this great link from Isuzu Japan that shows that the 4JG1 did come from the factory in a turbo version (4JG1-T) http://www.isuzu.co.jp/world/product/in ... 1516090377

In this thread: viewtopic.php?f=19&t=7431&p=46077&hilit=4jg2+to+4jg1#p46077 Powertruck95 said: "Did some homework yesterday a friend of mine is a guru when it comes to Isuzu parts and he did a breakdown and found out that the 4JG1 shares the same head as the 4JB1 identical part numbers. The cranks are also identical." .... does this also apply to the turbo variants? Are the NA heads the same as the turbo heads?

In NZ and AU the 4JB1-T and 4JG2-T are quite popular in Isuzu vehicles but the 4JG1 was an industrial engine used in generators etc. and not so common.

So on to my main question, what is the EASIEST way to make a 4JG1-T out of donor 4JG2-T and 4JB1-T engines?

Is this the build? :
4JG2-T block, crank, rods & mechanical fuel pump
4JG1 or 4JG1-T pistons
4JB1-T head, injectors etc.

The only rare in NZ parts being the 4JG1 or 4JG1-T pistons.

I thought having this info on the forum would benefit more users than having it on Facebook.

Thanks in advance :)
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby isuzurob » Sun Sep 10, 2017 5:16 pm

There has been alot of this going around, best way is use a 4jh1-t direct injection engine and use a manual injector pump on it, im building 1 at the moment with 12mm pump high flow injectors and a td04hl turbo set to 20psi for my 89 bighorn
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby rabidrabbit001 » Sun Sep 10, 2017 11:25 pm

Gomulletgo,

Is this the build? :
4JG2-T block, crank, rods &
4JB1-T mechanical fuel pump
4JG1 or 4JG1-T pistons: http://www.partsfamily.net/isuzu-4jg1-4jg1t-engine-rebuilt-kit-p-808.html
4JB1-T head,
4jh1t injectors/hardware
Steve Dallas said he used 4jg2 injector lines had to bend a little to make work.
I had to cut h1 lines and splice with compression fittings b1 line ends at pump
4jh1t metal multi layer head gasket
I did all the polish work so that it is as efficient as possible for a 8 valve engine.
Last edited by rabidrabbit001 on Sun Sep 10, 2017 11:37 pm, edited 1 time in total.
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby rabidrabbit001 » Sun Sep 10, 2017 11:33 pm

isuzurob wrote:There has been alot of this going around, best way is use a 4jh1-t direct injection engine and use a manual injector pump on it, im building 1 at the moment with 12mm pump high flow injectors and a td04hl turbo set to 20psi for my 89 bighorn

That's nice that you have a 4jh1t engine to start with mate....but what about those people who have 4jg2t and want more fuel economy and more power and reliablity of the good ole 4jb1t and can't just drop the coin for a whole other engine platform? From what I have read the only reason the 4j diesel engine were not used in the US market was that it made to much mechanical noise. LAME EXCUSE US MARKET DUDES!!!
P.s. I really like the sound of the td04h 15t turbo upgrade.
I'm currently boosting 20 psi with the stock/rebuilt 4jg2t RHB5 turbo.
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby isuzurob » Mon Sep 11, 2017 5:27 pm

Guy that asked is in nz lots of 4jh1 engines around I brought 3 complete trucks, by the time you buy all the bits to build engine be the same just to buy a 4jh1?? Then have factory reliability, mine has high flow 11 blade turbine wheel and 16t extended tip compressor wheel
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby geeves » Mon Sep 11, 2017 6:51 pm

how easy does the 4jh1 bolt to a trans for a 4jb1 or do you swap the trans as a set
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby isuzurob » Tue Sep 12, 2017 4:15 pm

Straight bolt in same block
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby geeves » Wed Sep 13, 2017 5:44 am

thats cheating
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby isuzurob » Wed Sep 13, 2017 6:52 pm

Nope just the smart way
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby rabidrabbit001 » Thu Sep 14, 2017 10:01 am

So what is the newer Manuel 4×4 transmission that the 4jh1t bolted to? And if the 4jb1t will bolt to it then a 4jg2 will too right? And is there a newer transmission that is heavier duty than that one?
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby geeves » Thu Sep 14, 2017 10:32 am

My understanding might be incorrect but the 4j series engine split into 2 branches. 4jb1 4jb2 are the original engines I didnt realise the 4jh1 was the same block but it does make sense. 4ja1 is also this block. 4jx1 has a different bellhousing and very different block. I believe the 4jj1 is the same bellhousing although the engine is closer in design to the 4jb1 etc.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby isuzurob » Thu Sep 14, 2017 11:57 am

All the same other than 4jx1 engine mounts and clutch setups are different on each engine, it's never a straight swap changing engines, 4jh1 has a different gearbox and electronic transfer box that is rubbish
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby gomulletgo » Tue Nov 21, 2017 2:28 pm

@isuzurob , pm'd you :)
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby MISTIRIODES » Thu Jun 07, 2018 5:50 am

Hi to all, i successfully made a convention twice, and here are the steps: 1st project was 4JG2 crank, 4JH1 Pistons, 4JB1 (N/A) Con rod (its a weaker design since is for n/a engine and the piston pin is thinner, as 4JH1T Piston are. Head is from 4JB1T, Also VE pump.
Results : unbelievable torgue, especialy at low end rpm, in fact so much torque that my cluch disk couldnt stand a simple petal press with the fourth gear. 2 bar turbo pressure and going so. BUT... After a month or so suddenly 1 con rod gotten cut and a lsrge side hole appeared on cylinder. This happened when engine was almost idle, no pressure or pump ip or anything, reqular start from stop and boim... Probably man error on tighten the con rod bolds.
--------Second attemp: 4JG1T PISTONS, 4JG2 Con rod and crank shaft, everything else 4JB1. Notes;b now has only torque, not the same power feeling but torque is amazing, forced to replace fly wheel and disk with 4jG2. Feels good in terms of torque but on high rpm no good power. Again turbo now runs at 1.8 bar on max and it feels like shes thursty for more fuel (4jb1) next step is 4jb2 pump with mods.. If you need any advice let me know.
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby muffinmonsta » Thu Jun 14, 2018 9:31 pm

MISTIRIODES, in the last sentence where you state "next step is 4jb2 pump with mods...did you mean 4jg2 pump with mods?
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Re: Making a 4JG2-T into a 4JG1-T with common parts

Postby MISTIRIODES » Mon Jun 18, 2018 7:44 am

Yes sorry 4JG2, wrong typing:) anyone run a 4JG2 PUMP on Direct injection here?
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