Bigger compressor wheel ...4jbit.(RHB5)

[oscarg]

I have a 96 rodeo with 4jb1t..... Has 3" exhaust & dump, 3.1 jackeroo top mount intercooler, k&N air cleaner, and has had the fuel pump tweaked a touch.

Goes much better than standard, but thought I could now afford to run a couple more pounds boost..........but after installing a bleed valve to the waste gate actuator, I can only manage a measly 1 or 2 psi increase with the the bleed off wide open.

Have read many tales of being able use a myriad of different compressor wheels and housings from Subaru's, Mazda, etc... but can find any definitive info as to what wheel will work - and if it will even fit to my rodeo's RHB5.

Can anyone shed any light?

[Jimmu]

Mine will boost to 20 psi if I let it.

Try disconnecting the waste gate tube entirely and rev her up to 3k or so and see where the boost goes.

You should be able to get some more out of it that that.

Jimmy

[oscarg]

That's all it seems to want to boost up....with the actuator hose off completely - No problems with the turbo, it's good as gold. I have read other posts where people say they can't get to much boost out of the standard turbo on the 4jb1t as well.

My engine has the old plain bearing RHB5...... Is this what you have?

[Jimmu]

To be honest I could not tell you if it was or was not. I am confident it is the standard item though.

Maybe the MU has a different turbo to the Aussie 4JB1T

Jimmy

[pig75]

The 2.8 MU has a VI87 and the 2.8 rodeo/jackaroo has a VI58. The VI58 has a 2mm bigger compressor wheel.
Where are you taking your boost readings from? Before or after the intercooler.

[oscarg]

Before the intercooler.... so in theory there would be slightly less than that getting to the engine.

[James W]

Have you taken into account, removed or adjusted the relief valve on the inlet manifold?

[oscarg]

No.....The Rodeo's don't have any "overboost" relief valve that I am aware of.