4jb1 pistons

This is the place to discuss DIESEL engine modifications.
KarlssonOnTheRoof
Regular Member
Posts: 7
Joined: Mon May 15, 2017 9:17 am
Location: Arvidsjaur Sweden
Isuzu vehicle(s): 1985 Isuzu Pup longbed 4x4 With 4ja1 Now With Turbo running 30+ psi boost:) 1989 Isuzu Trooper with 4jb1-T

4jb1 pistons

Postby KarlssonOnTheRoof » Thu Aug 03, 2017 7:52 pm

I bought a isuzu trooper with a 4jb1T for 500 swedish kroner or a little les that 50 dollars the engine is in bad shape but it ran the cylinder liners are bad and the second piston was burnt so im going to rebuild it. The trooper is free from rust but need a bit of work

It has square bowlpistons

Are ther any preformance differens between the square bowl vs round bowls in the pistons?

I know the round bowls are later modell and in my head that means its better for preformance but i dont know for sure

And if the round bowl pistons would just be a swap in or if i need to change the injection nozzel?

downunderyank
Regular Member
Posts: 307
Joined: Wed Feb 10, 2010 10:15 pm
Location: Hutchinson MN
Isuzu vehicle(s): spacecab diesel Holden rodeo 1993, 1986 pup spacecab, 1987 pup spacecab
Contact:

Re: 4jb1 pistons

Postby downunderyank » Sat Aug 05, 2017 4:30 am

I have pulled a lot of 4jb1t's down and rebuilt a couple, I have never seen any difference in the cylinder head between the square and round top pistons. The injectors are also the same so I see no reason why you can't just order a kit with the newer style pistons and have at it.
converted '86 diesel spacecab

KarlssonOnTheRoof
Regular Member
Posts: 7
Joined: Mon May 15, 2017 9:17 am
Location: Arvidsjaur Sweden
Isuzu vehicle(s): 1985 Isuzu Pup longbed 4x4 With 4ja1 Now With Turbo running 30+ psi boost:) 1989 Isuzu Trooper with 4jb1-T

Re: 4jb1 pistons

Postby KarlssonOnTheRoof » Sun Aug 06, 2017 7:00 pm

Okej, thanks a lot i want to get the most reliable power out of my 4jb1 and if im not wrong the round bowls on the N/A version gave it 3 hp and i think its a bit more than that on the turbo model