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Hi from USA, modding my 4jb1t for power.

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Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Sat Jul 07, 2018 9:14 am

Hello all,

First post here, member of other isuzu and diesel forums but just found this one. I do drainage and irrigation systems during the day, and mod diesels and build custom turbos during the night.

Im picking up my recently imported-from-austraila 4jb1t next week along with a genuine overhaul kit. Putting it into my restored 86 Trooper II. I know the gen 1 troopers are weak so it will take throttle management should i ever want full power.

Right now my current plans are after a good cleaning at the machine shop and proper rebuild are as follows:

Ceramic coat top of pistons for protection
Replace the crappy ihi rbh5 turbo and install a custom garrett gt1756 with water-cooled center housing, built by me.
Add a garrett gt2867r turbo on top of the 1756, and add a water-to-air intercooler.

Ive read a thread here that a guy installed 4jh1 injectors and a 12mm pump head with good results, any validation to this?

This is my first 4jb1t, they arent very common here, so im open and will welcome any experience/advice/tips on this engine from you all that have been around these.

My power goal is a reliable, cool, easy 250hp, which is why im using twin turbos, at 250hp both turbos will be running at a measley 1.6 pressure ratio, keeping shaft speed and bearing speed low. And piston coating to keep as much heat out of the pistons as possible.

Any feedback welcome!! -Joe
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Re: Hi from USA, modding my 4jb1t for power.

Postby tonkamu » Sun Jul 08, 2018 4:03 pm

Hi, what gearbox will you be using for that amount of power?
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Mon Jul 09, 2018 12:34 am

Ill be swapping out the msg for an mua
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Mon Jul 16, 2018 4:48 am

Wow guess i didnt realize this is a somewhat slower-moving forum. Thats ok, ill update as the build goes, have the engine now and turbo parts ordered. Next the piston rings are being sent out to be converted to gapless rings for better efficiency/ compression. Pistons, bearings, and valves are going to be sent out for their respective coatings.

Fuel system will be the next to be worked on, but that will be awhile until im at that point.

-Joe
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Re: Hi from USA, modding my 4jb1t for power.

Postby geeves » Mon Jul 16, 2018 3:49 pm

Not many are going for max power at any cost. The 4jb1t is a great engine already and does quite well in standard form and plenty well enough with quite minor mods. We know there is more to get out of that engine but at the same time its bullet proof reliability and excellent efficiency (compared to other pre common rail engines) are the reasons a lot of people go for that engine. They want an engine that is good for half a million km or more they want 8l/100km economy out of a 2 ton truck and these engines will still achieve that when tweaked to 120 or so kw. Going further is possible but doing it while keeping drivability and reliability takes a lot of money as you know and you have better access to technology we can only dream about down here.
Do a search for a user name superturbocompound. He hasnt been active here for a long time but he was building 4jb1s for drag racing. From memory he got a Mu (Amigo) down the quarter at 85mph and 18 seconds using a 4jb1 running custum turbo compounded with a supercharger. Last I heard he was playing with 4JH1 engines which are a 3 litre version with improved heads etc. You start with a bigger and better engine and they were getting fantastic results but I can imagine what these would be like in the morning commute.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Mon Jul 16, 2018 11:16 pm

Hi geeves, ive seen superturbocompound a few times on here while reading through. I think hes at a level far beyond where i want to be. And besides the piston rings, everything else im doing can be done at home. The coatings can be diy if you have the time, i just dont.
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Mon Jul 23, 2018 3:18 am

Well i decided to do the coating on my own, this build is going to take some time and figured i could squeeze some coating in here and there. its a pretty simple process. First the parts are blasted with 120 grit aluminum oxide, cleaned with acetone, baked in an oven at 450°f/232°c to burn everything off. Spray it on with an airbrush and then bake at 350°f/176°c for an hour to cure.

For the piston tops i bought techline coatings cbx designed for high compression/nitrous/turbocharged engines. Im going to coat the valve face/back, exhaust port, and the exhaust manifold/turbine housing with this stuff to keep as much heat in the exhaust as possible. Image

Heres the link to where i ordered it from: https://www.powderbuythepound.com/cbx_-3_oz.html

I also sent my rings to Total seal, they converted my second rings to gapless. They wouldnt do the top rings because they are cast and didnt want to make them thinner. They did quote me ~$230USD for a whole set made by them that are gapless for anyone interested.

http://www.totalseal.com

-Joe
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