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Modding my 4jb1t for 250hp

Getting the best performance from your Isuzu, the in's and out's

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

Postby dieselguy86 » Mon Jan 07, 2019 11:26 am

Ill use the 4jb1 sticks then.

On another note, i finally have my other turbo figured out, and its quite the hybrid haha. To start out, im using a vf34 ball bearing center section, a vf38 lightweight turbine, a vi95 (4jg2 turbo) exhaust housing, and a vifb compressor wheel and housing. This gives me a 40mm turbine with the standard ihi bolt pattern to the manifold, and a 41mm compressor. Best part is, i got it all for $850, and its all bolt together, should have really fast spool with the lightweight rotor and ball bearings, and enough air for 200hp. Ill post lots of pics as i build it.

I also ordered some ceramic dry film lube. Ill be coating the main, rod, and cam bearings, valve stems, and the cam and lifters.
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Re: Hi from USA, modding my 4jb1t for power.

Postby isuzurob » Tue Jan 08, 2019 4:18 pm

The 4jh1 injectors will fit and work just spray pattern is different and if your going for high power you want the pattern to match the pistons other wise the risk of cracking them is far greater
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Re: Hi from USA, modding my 4jb1t for power.

Postby isuzurob » Tue Jan 08, 2019 4:21 pm

Oh and if you run 4jh1 injectors you will have to make new injector pipes as the 4jb1 pipes dont work as I found out
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Re: Hi from USA, modding my 4jb1t for power.

Postby tezbang4jb1trodeo » Sat May 11, 2019 2:17 am

Sounds like a fun project. Will be following progress. Just in case you haven't already dont it but will need to run a lot stronger valve springs running 38psi of boost.
Looking forward to progress.
I have a spare 4jb1t that I'll be stripping down and doing something similar and then swapping with my stock one.
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Sat May 11, 2019 9:09 pm

Hey guys, just letting you know that upgrading the crank is probably going to need to be on the table for these hi power builds on the 4JB1T. Snapped the crank a few days ago on my setup, this was with 11mm fuel injection pump on my compound setup whilst running 35psi. Currently looking at options to use a stronger crank. I have a spare engine but reluctant to just use it as the same thing will probably happen. Not too many options when it come to cranks with these things.
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Sat May 11, 2019 9:12 pm

tezbang4jb1trodeo wrote:Sounds like a fun project. Will be following progress. Just in case you haven't already dont it but will need to run a lot stronger valve springs running 38psi of boost.
Looking forward to progress.
I have a spare 4jb1t that I'll be stripping down and doing something similar and then swapping with my stock one.


Doesn’t seem to be an issue, ran up to 46psi on my compound setup without valve issues.
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Re: Hi from USA, modding my 4jb1t for power.

Postby geeves » Sun May 12, 2019 3:00 pm

valves are held closed by cylinder pressure. The issue that requires stronger springs is higher revs. This doesnt really apply to diesels
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 tezbang4jb1trodeo » Wed May 22, 2019 4:20 pm

Ah yeah okay, have always done springs on petrols when doing high horse power, high revs makes sense.

Upgrading crank sounds expensive.
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Tue May 28, 2019 10:34 pm

Y
tezbang4jb1trodeo wrote:Ah yeah okay, have always done springs on petrols when doing high horse power, high revs makes sense.

Upgrading crank sounds expensive.


Yes upgrading the crank is expensive, billet crank would have to be made probably $4k. The only other option is to get the factory crank Cryo treated to strengthen, which is the path I am going to go down. Anything around the 200hp + is going to be playing with fire on a stock crank. The crank in mine had a hard life, around 60-70 runs down the quarter mile and daily driven. Hopefully cryo treatment gets it over the line strength wise, pretty much out of options otherwise.
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Fri Jun 14, 2019 1:24 am

Hard to believe it snapped, these isuzu cranks are built really heavy duty. 200hp isn't far from the stock hp, i wouldn't think they'd spec such a critical part so close to failure.

On another note, how'd that 2871r do? My math said it was a little small for smoke free power higher in the revs, but i bet it spools up really nice!
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Tue Jun 18, 2019 1:42 pm

dieselguy86 wrote:Hard to believe it snapped, these isuzu cranks are built really heavy duty. 200hp isn't far from the stock hp, i wouldn't think they'd spec such a critical part so close to failure.

On another note, how'd that 2871r do? My math said it was a little small for smoke free power higher in the revs, but i bet it spools up really nice!


Have had a few engine shops say they have seen plenty of snapped cranks in the 4jb1t’s particularly the earlier ones. Was alway expecting it as a weak link. The torque going through the crank was nearly 3 times factory output so never expected it to last long. As for turbo sizing, never really has it going long enough to get set up well or dyno it. Definitely went better, but don’t have anything on paper. Will have it all up and running again in a few weeks, rebuild with lots of upgrades. And 12mm fuel pump. Just need to sort out injectors that will flow better
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Fri Jun 28, 2019 12:08 pm

Let me know what you come up with on injectors, I'll be needing a set myself. Have a 12mm pump head to install too. Did you do anything to your cam?
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Thu Jul 04, 2019 7:21 pm

dieselguy86 wrote:Let me know what you come up with on injectors, I'll be needing a set myself. Have a 12mm pump head to install too. Did you do anything to your cam?


Still scratching my head with injectors, extrusion honing might be an option to go bigger and keep the correct spray pattern. As for the camshaft, had one the local cam gurus work their magic on the cam, a little more lift and changes in duration, lobe separation, nothing too extreme thought. After I get it going again I will probably not take it too much further. I have an Isuzu 4BD1T 3.9L I want to start working on it for another drag Ute project
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Fri Jul 05, 2019 12:04 pm

Do you know if the 4jb1 injector nozzles fit into the 4jh1 injector bodies? Talked to a guy on messenger that installed the 4jh1 injectors and remarked about how much quieter it ran, but i was told earlier in this thread not to use the 4jh1 injectors because the spray pattern is different.
Then read another post dated from 2015 that there are different nozzles available for the 4jb1, from a 4 hole for the square bowl pistons, up to 7 hole nozzles. It would be nice if 7 hole nozzles could be put on the 4jh1 injectors.

Here in the states almost everything is common rail, getting old mechanical injectors honed is getting harder and harder.
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Fri Jul 05, 2019 1:08 pm

dieselguy86 wrote:Do you know if the 4jb1 injector nozzles fit into the 4jh1 injector bodies? Talked to a guy on messenger that installed the 4jh1 injectors and remarked about how much quieter it ran, but i was told earlier in this thread not to use the 4jh1 injectors because the spray pattern is different.
Then read another post dated from 2015 that there are different nozzles available for the 4jb1, from a 4 hole for the square bowl pistons, up to 7 hole nozzles. It would be nice if 7 hole nozzles could be put on the 4jh1 injectors.

Here in the states almost everything is common rail, getting old mechanical injectors honed is getting harder and harder.
.

Not sure on the interchangeably of the injector nozzles. There were early 4hole injectors in the 4jb1, then they went to a 2 stage injector, these are the smoother running ones. I’m stuck with 4hole injectors as I already had a set of ceramic coated square bowl pistons. If you go the round bowl pistons you have a lot more options. I am possibly going to look at going to a bigger body injector and machine the head to suit, something like a 4bb1/4bd1 injector. Haven’t followed the injector issue up much just going to do some testing with what I’ve got
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Fri Jul 05, 2019 2:32 pm

Is there any part #s for the dual stage or atleast a pic i can compare mine too? I have a ways to go till I'm at the fueling stage, so I'll be watching to see what you find out.
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Re: Hi from USA, modding my 4jb1t for power.

Postby paulthepilot5 » Fri Jul 05, 2019 10:28 pm

dieselguy86 wrote:Is there any part #s for the dual stage or atleast a pic i can compare mine too? I have a ways to go till I'm at the fueling stage, so I'll be watching to see what you find out.


I don’t have any part numbers on hand, but there are exploded diagrams of both injector types in the 4jb1t workshop manuals that are online
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Re: Hi from USA, modding my 4jb1t for power.

Postby dieselguy86 » Mon Jul 08, 2019 11:24 am

Well, my original plans for today was derailed when my 2yr old son woke up sick. So i got to spend most of the day doing nothing, which i used to research nozzles.

I found a Spanish manual that told me what nozzles were used in what engines. The early 4 hole, square bowl piston 4jb1ts used zexel p/n DLLA146PN-055. This nozzle is a 4(hole)x0,30(mm)x146°(spray pattern in degrees) [4x,30x146°].
Going down the list i found 2 more listings for nozzles. Im guessing one was for the latter round bowl engines, and the other for the intercooled version? Those numbers are;
DLLA153PN177 [5x0,25x153°] and
DSLA149PN903 [5x0,26x149°].

The one thing i can't find, is a paper that breaks down what the numbering system means. For instance the difference between DLLA and DLSA, the middle 3 numbers obviously tell the degree of spray pattern. The 2 letters behind that i don't know, ours are "PN", there's also "SM" that have alot more options in both hole size and amount. If you work out the area of the stock injectors, it works out to .245mm³, I'd like to go around 50% bigger, so .245x1.5=.3675. Which divided up into 6 holes they'll need to be .28, which they're is no 6x.28 "PN" nozzles. If i do 5 hole id need .30, there is a 5x.30x160°, but not for the double spring.

Might make the call tomorrow to a semi local injection shop to see what they can do. I know they can make custom nozzles, just not sure on price.

I know i rambled somewhat, it's just a good way for me to "log" what I'm thinking so i can go back later.
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Re: Modding my 4jb1t for 250hp

Postby dieselguy86 » Thu Jul 11, 2019 11:59 am

Ok, found more info, here's how the nozzle coding works.
I'll use the 4 hole nozzle as a reference DLLA146PN-055

D stands for nozzle,
L means hole type injector, N is for pintle for the idi diesels, and S means sacless nozzle
L is for long shank, there is also S which stands for short
LA means there is no ring groove, and dowel pin hole is 90° from fuel duct.

The 146 is as stated before, the spray angle.

P means it has a 14.3mm nozzle body collar diameter.
S is 17mm,
M is 14.6.

The last 3 digits is simply the "serial number" in which that nozzle was designed/ made. For instance -056 doesn't mean it's an upgraded nozzle. It was just the next one designed after -055.

The PN, SM i was talking about before is Zexels spin on Boschs P and S designation, probably to keep from having the exact same numbers.

So after figuring all that out, i found some Bosch DLLA149P-601 which has a 8x0,23x149° hole pattern. This is just slightly below the 50% increase i was looking for, and is right in the middle of the range of the spray pattern degree ive been finding, as well as also meant for a 2 spring injector body.

In the next day or so im going to see how easy/ hard an inline Bosch A pump will mount to the timing case, just for experimental purposes 8-)
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Re: Modding my 4jb1t for 250hp

Postby dieselguy86 » Fri Jul 12, 2019 2:23 pm

Just for anyone who might be thinking of it, an A pump will not bolt up to the timing case on a 4jb1. I mean it could with some machining, but way too much trouble than it would be worth.
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