Modding my 4jb1t for 250hp

[dieselguy86]

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

[tonkamu]

Hi, what gearbox will you be using for that amount of power?

[dieselguy86]

Ill be swapping out the msg for an mua

[dieselguy86]

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

[geeves]

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.

[dieselguy86]

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.

[dieselguy86]

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.

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

[dieselguy86]

*Warning: lots of pics* haha

Rings came in yesterday, and half of the turbo parts. The other half are in, but not delivered.

Ill start with the rings...


You can see the second ring had a step machined into it, and what they call a “rail” is fitted into it. The rails gap is installed 180° from the second rings gap.


A somewhat decent pic of the step machined into the ring.


Second ring fitted with the rail to show how it is assembled.

Next is the turbo. This one will be the second turbo, known as the atmosphere turbo, or low pressure turbo. It will suck the air in first, compress it, and send it to the smaller turbo on the manifold, also known as the high pressure (hp)turbo. This is a custom Garrett GT2867r turbo that i am custom building for this engines needs. I went with an 8 full bladed wheel as these work extremely well on low pressure systems. This will send 10psi of boost to the hp turbo, where it will be compressed again to achieve the 38psi ill need to produce clean, smoke-free power.

[geeves]

Looks nice

[dieselguy86]

Well my wheel for the high pressure turbo FINALLY came. I mocked it up quick to make sure it fit. Turbo is a bit of a hybrid, center housing and exhaust housing are from a saab 2.0. Exhaust wheel is a gt17 from a volkswagen diesel, the intake backplate and housing are from a VM 2.8 common rail out of a jeep.

The wheel isnt a standard design, its best for low boost/high flow. This will be receiving ~13psi of boost from the larger turbo, and compressing it again 1.9x to my final 38psi. Im going to have to intercool the air inbetween these two. If i didnt the air leaving this turbo would be close to 500°f (260°c)at full-throttle. There will be a decent sized water-air intercooler before going into the engine to drop temps down to normal.

[dieselguy86]

Ok so i spent some considerable time looking at glow plugs. The c223t in the US market came with 5v plugs, the 4jb1 uses 11v. I wanted to keep my working isuzu QOS to keep it as factory as possible. I know that sounds funny since im adding another turbo, but the turbo isnt integrated into the vehicle like the glow plug system. Sensors, fusible links, controllers, etc. i really didnt want to hack up the “system”, so my hunt began.

Downloading the Bosch glow plug product catalog gave me all the measurements i needed:


The m12x1.25 is a somewhat uncommon size, had it been m10x1.25 it would have been much easier.

I couldnt find anything of bosch that was 5v, but a look through denso’s glowpug catalog showed a perfect match, down to the mm and 6v. Denso glowplug DG-241:


The only downside is these arent available in the states, so i had to pay $60usd for 1 plug shipped from uk. I want to make sure everything fits as it should before i spend a whole lot of $$$ on plugs. Ill have to make a new bus bar, but atleast i should have a factory performing system.

-Joe

[geeves]

Where in USA do you live? Chances are that you wont need the glow plugs as that engine will start without a glow down to 0C

[dieselguy86]

Wow, totally different animal than the c223t, that needed a glow below 15°c. Depending on the weather pattern ive seen anywhere from -40°c to +4°c. I live in northern ohio so we can get what we call “polar vortex’s” come out of the arctic. This will be garaged in the winter so I really wont have to worry, but i wouldnt be able to stand knowing i wouldnt have a functioning glow system.

[geeves]

The record low in the city I live in is -3C That took up 5 pages in the newspaper. The airport was closed for a couple of hours trains stopped running etc. People in Nz wouldnt even comprehend -40.

[dieselguy86]

The -40 was a somewhat rare event, and was a whole different type of cold. Alot of peoples cars over-heated because the snow would melt on the radiator, and then freeze. It would keep building up until the entire radiator was froze over. Your nose hairs would freeze everytime you inhaled, it was wild. The normal range is -20 to +4. Believe it or not but my il c223t started in that -40 with a block heater and a freshly restored and operational Quick On System.

[dieselguy86]

Been a bit, time for an update.

The stock exhaust manifold has an ihi turbo bolt pattern. Didnt measure it but i need a garrett t25 bolt pattern. The easiest thing i could think to do was to weld the flange on and machine the manifold out to match. The t25 pattern is alot bigger and will definitely open the manifold up more.

Here the flange is only tack welded into place, and starting the machining. It is a tiny hobby mill and this filled it up. Ive got the bulk of the excess material out of the way now, ill take it to work tomorrow and use a die grinder to remove the rest and blend it all.





Before i forget, the new glowplug arrived and it fit PERFECT. Still stoked about it lol.

Also, ive ordered a couple needle bearings, im going to experiment and see if i can machine the block and cam to accept needle bearings. Obvious advantages are more power freed up, less oil flow needed, and smoother running. If it can be done or not i cant say yet, ill have to have a good chat with my machine shop.
Been doing some research into retro-fitting some roller rockers too, not easy as i thought it would be. Fortunately for me summit racing is 1hr 45min from me, so i might run over there and see if they can help match something up.

[dieselguy86]

Almost 5 months since an update! Work and life kept me out of the garage, but here it is winter time so i have some more time to get back on this project.

Ive scrapped my original turbo idea. Wasnt making me 100% happy. Ive decided to go with an IHI vf38 hybrid turbo for the high pressure turbo, and a Borg Warner EFR 7163 turbo for the low pressure. Im not done with the VF38 so ill leave those details out, but the 7163 is awesome, its the exact turbo used on indy cars, and the math showed it was a perfect fit for this application. Features dual ball bearings, a very lightweight titanium-aluminide exhaust wheel, a forged milled compressor wheel, aluminum water-cooled bearing housing, and stainless steel exhaust housing.



I also received my 12mm pump head today, and will be dropping the pump off at my local fuel injection shop to clean, re-seal, install the new head, and recalibrate the pump.

Hopefully ill get the pistons all ceramic coated within the next couple weeks, then the rotating assembly will be sent out for balancing. After that, itll be ready to assemble. Still need to get some 4jh1 injectors. Anyone have a set? Or can get a set? Hard to find here in the states.

[isuzurob]

4jh1 have a different spray pattern to 4jb1 injectors as the pistons are different so just run 4jb1 injectors

[dieselguy86]

Could you explain a little more what you mean? The 4jh1, 4jb1, and 4jg1 all have relatively the same size/shape bowl in the same spot of the piston. The only thing that could change the pattern would be if the injectos are installed in the heads at a different angle. The size and number of holes may be different too for a cleaner burn, but as long as the installed angle is the same that shouldnt matter.

That being said im definitely open to listening to experience.

[geeves]

I think the 4jj1 is closest to the 4jb1