pumping up boost on 4JB1T

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pumping up boost on 4JB1T

Postby Leedo » Thu Nov 27, 2008 6:42 pm

hello folks,

does anyone who owns a rodeo know how much boost you can safely (and practically) run on a 4JB without an intercooler.

I understand the temp of air charge without a 'cooler is high and i can only assume it gets higher with more boost . my deo pumps up 10psi on my aftermarket gauge.

also would i have to advance/retard my injection timing to optimise the increase in boost.:confused:

Leedo
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Postby The Vulcaniser » Fri Nov 28, 2008 4:20 am

the easiest way would be to put a spring with an adjuster on it to hold the waste gate shut for longer...... or just get a boost controller off ebay....... it would work ok. coecruiser from this forum has one on his 60 series. The most you will get out of the turbo on the deo is about 14psi max. I had mine intercooled when i had it and it was retuned on a dyno and was pushing about 90kw (72kw standard) and about 340nm of torque (220 standard)
I didn't get the injector pump retimed, but i read on the Isuzu forum in the US that with an intercooler and the injector pump adjusted they are getting around 150hp (112kw) out of the 4JB1T engines.
Just an intercooler will give it an extra gear pretty much. Mine would power up hills with 4 adults in it and a load of gear on the back.
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Postby KRUZIN » Mon Dec 01, 2008 10:52 pm

a 2 1/2 inch zorst makes a world of difference to these engines.

adjusting the timing helps power as well, only you have to know what your doing....you dont actually "adjust" the timing, you adjust the amount of fuel injected at a certain point. very easy to adjust with minimal tools.

on a later engine you can simply "shim" the wastegate actuator with washers to adjust boost, on earlier ones you can shorten the actuator pushrod to increase boost, a nifty adjustable rod would be ideal here...........
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Postby Leedo » Tue Dec 02, 2008 7:12 pm

so in your honest opinion doing the boost controller mod without an intercooler would not lead to premature engine failure. my engine is mechanically sound after haveing smashed rockers and bending push rods when my timing belt falied a few 1000kays ago.

I'm just looking for some cheap safe power gains and thought this would be the go.

Leedo
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Postby KRUZIN » Wed Dec 03, 2008 12:05 am

no one these days will openly say that certain mods wont affect engine longevity.....

BUT.... certain inlet (eg : a snorkle) & exhaust mods will give reliable power gains.

& without being excessive... timing/fuel & boost mods CAN/MAY give good power increases without significantly reducing engine longevity.
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