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Isuzu 4JB1 N/A to Turbo

503 Views 12 Replies 5 Participants Last post by  Dougal
Would be planning to run an Isuzu 4JB1 N/A (around 80hp and 130lb/ft torque) with turbo low-boost system (just to shove air in and keep smoke and EGT down)

The Isuzu 4JB1 I'll be using is a early truck type unit (no oil cooler, 4-hole injector with square bowl piston), would not run a turbo I/P as stock N/A power level would be sufficient but needed to be efficient at 1,400-3,500rpm with my cruising RPM range from 1,500-2,600rpm at 30-60mph.

Would also need to assess whenever I need intercooling and if the vehicle needs to be regeared when necessary.

My vehicle would be an '89 Toyota Crown, with 3.91 rears, W55 tranny, 205/55R16 tires and grossing at 3,000lbs estimate.
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What was the motor in originally?

Have you found torque and power cures for the motor?



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This would be the nearest power curve that I could find roughly.
I owned an early-80's Toyota with the 2.2 NA Diesel; and a 220D Mercedes. Both those motors made up for not having any power, by not having any torque.The experience left me without any fondness of under-powered vehicles.

That Crown seems the perfect place to drop a VW TDI. But, I know that's not what you're asking.

What did your motor come out of? What transmission and gearing?
Stock W55 tranny, 3.91 rears with 205/55R16 tires.

Could be better with 4.30s but would be always prefer lower RPMs as I often drive around 55-60mph on highways
Isuzu Rodeo in most places, would have a different name in the US, some very small Isuzu trucks. The 4JB1 and 4JB1T are not a common engine over there. In stock form a 4JB1T is around 100hp at the flywheel, so usually about 60-70 at the wheels. Without any major mods, just good intercooling guys are getting around 120-130hp at the wheels, turbocharger is the limitation here. If a more suitable turbocharger is used the Injection pump will max out around 135-140hp ATW. It is common to upgrade injection pumps and turbo and push a lot more power anything north of 25-30psi and upgrading to head studs becomes a consideration. As an example of what they can achieve, I’ve run over 300hp 640nm at the wheels, with an inline injection pump conversion. You just have to look at what the Thai’s do with them drag racing some would have to be running north of 400-450hp for the 1/4mile times they achieve.
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Saw an A-pumped industrial 4JB1 for around $1000 but located way up north
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