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hey all, whats the common upgrade from the small factory turbo on 2.8 MU. I hear the 98 - 03 4jb1t Mu's run a bigger compressor turbo and bolts straight onto the older 4jb1t manifold.

Planning on changing oil filter housing and getting the 2.5" turbo back pipe before getting a bigger turbo.

I don't want to big, I'm after more torque and faster spool up.. anything under 1400 rpm would be nice.

Anyone have options that worked and any details would be of big help.

My old 89 bighorn still had a factory turbo (I bought the car at 92000km) but it did have snorkel unifilter and 2,5 inch exhaust. That would hit 10 pound boost by 1500 and 15 by 1800 which it would hold till 3800 only dropping to 12 when the rev limiter kicked in.
Bigger turbo would see more power at the top end but would not be great at low revs. Short of a custom turbo from the a turbo specialist you could easily be disappointed with the result. A good 2.5 inch exhaust with open muffler will see good gains across the rev range especially at low revs. Also see what you can do to make the intake breathe better. The Mu isnt to bad but the bighorns settup would seem ahsmatic to a Pug

yeah mine hits 10-12 easily, getting it to 17 takes some time. My turbo is quite small, I think once you have all the other mods (intake and exhaust) a slightly bigger turbo would see good gain over the factory one. I'm not looking for a big one as the engine would struggle with it. But I heard the later 4jb1-t engines (98-03) ran slightly different set up. But its hard to find those wrecking and I've never seen one up in person.

Later model 4jb1 runs a smaller turbo and exhaust manifold I have a turbo if you want to buy, ideal turbo is off a 89 s spec bighorn they have a 12r exhaust housing and good flow compressor and will bolt straight on, also can run a vf10 or vf8 compressor and core in your factory exhaust housing, more fuel equals less lag but higher egt if no done right

Yeah after a upgrade/replacement. I'll send you a PM Rob.

Hey all what size tubing do I need to get welded onto my vf10 compressor housing. is it 46mm outer diameter 2mm thickness and extending out 20mm?
If so having trouble finding 46x2 mm tube.

thanks

Edit* Nevermind measured the vf10 compressor hole its 50mm, I should have done that to begin with. So can't re-use my plastic inlet pipe.

Hey all, just needing some guidance on installing my vf10. I've found a cheap 3inch downpipe and adapter for using exhaust housing from the vf10 with the Isuzu manifold and downpipe came off a vf8 on an MU it was installed he was running free boost 30psi till the bearing went.

My question is..is the oil feed/exit pipes meant to face top/bottom (gravity fed), as on my vf8 one of the oil pipes is facing the direction of the manifold flange. Would that mean I need to turn the exhaust housing (as the downpipe wouldn't be facing down it waould be pointing out the side of the guard), I was told that these should bolt straight on how it is, but for me I can't understand how that works. This is all new territory for me.

Update: $200 to get exhaust housing turned and new bolts as the last were really rusted and also they got the shaft spinning nice and freely it was stiff before hand. $50 for the new gaskets for adapter and housing. Will try to use my old oil pipes after a clean out.

Currently in middle of changing turbo set up. Have gone for complete vf10 turbo with its Subaru exhaust housing and a custom straight downpipe off turbo back. The size difference is really apparent, hopefully it spools under 2k. The inlet is a big 3" to filter/snorkel.

A/C pump has been deleted in order to fit the larger turbo, ran shorter belt from crank to p/S pulley.

Size difference between factory turbo and vf10 Subaru.
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Hi all, I have just a stupid question. Should the downpipe go on after turbo is bolted on or before turbo is bolted on Its a custom downpipe 2.5". I Can't get the downpipe over the studs, and the clutch slave cylinder gets in the way.

Turbo is going back to get studs removed as they are well stuck. just wanting to know im on the right track I'm hoping it will slide on the back with no studs... It has not been as easy as I thought, definitely not quite (straight bolt on) I had to cut up my oil drain pipe, I've not got to oil feed yet. Big learning curve for me.