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2.8 MU Turbo upgrade options

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2.8 MU Turbo upgrade options

Postby tonkamu » Sun Jan 21, 2018 1:55 pm

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.
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Re: 2.8 MU Turbo upgrade options

Postby geeves » Sun Jan 21, 2018 2:33 pm

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
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Sun Jan 21, 2018 2:40 pm

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.
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Re: 2.8 MU Turbo upgrade options

Postby isuzurob » Sun Jan 21, 2018 4:18 pm

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
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Mon Jan 29, 2018 1:30 pm

Yeah after a upgrade/replacement. I'll send you a PM Rob.
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Fri Feb 23, 2018 12:48 pm

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.
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Wed Mar 07, 2018 8:16 am

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.
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Fri Mar 09, 2018 5:44 am

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.
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Thu Mar 29, 2018 7:26 pm

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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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Thu Apr 26, 2018 1:20 pm

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.
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Re: 2.8 MU Turbo upgrade options

Postby geeves » Thu Apr 26, 2018 3:57 pm

Modifications often end in uncharted waters. The pipework could go on any way you can get it to work although looking forwards it would be ideal if you can remove the dump pipe from the turbo in situ without using every swear word in the book. Its not hard to take the clutch master cylinder off if needed.
A workmate had a rover v8 in a mk3 cortina. Every time he wanted to check the spark plugs it was a case of unbolting the headers and the engine mount and jacking up the engine to get at them.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 2.8 MU Turbo upgrade options

Postby paulthepilot5 » Mon Apr 30, 2018 7:10 pm

The stock turbo can perform very well if given a chance. If you are after quick spool up and torque don’t bother going bigger. Freeing up the intake and exhaust will make all the difference, Stock turbo will still go to 25+ psi. A dump pipe can be made to fit around the old style oil filter assembly, just a bit of mucking around.
To make life easy fitting the dump pipe take the studs off the turbo and run bolts into the turbo housing, this way you don’t need the rearward clearance to fit the pipe over studs. Get some loctite freeze and release spray to get the studs out.
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Mon May 14, 2018 4:06 pm

Could someone tell me which direction these water pipes flow to the oil cooler? I'm hooking up the 3.1 oil cooler to my 4jb1t mu and i'm being abit OCD with getting it right the first time. On the 2.8 oil cooler both pipes are level but on the 3.1 one pipe is at a lower level on the oil cooler.

Picture is just for reference, its not mine.


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Re: 2.8 MU Turbo upgrade options

Postby geeves » Mon May 14, 2018 7:42 pm

If you use factory hoses it will only go one way but I doubt it matters that much
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 2.8 MU Turbo upgrade options

Postby greegree » Mon May 21, 2018 9:24 pm

Hi there just wondering if the 3.1L turbo on the bighorn is the same as in the MU i would assume so but just want to know for shure (is the turbo different with the intercooler?). Also wondering if anyone has taken the intercooler from the bighorn and put it on the MU just seems like a good idea dont think the MUs came with them
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Re: 2.8 MU Turbo upgrade options

Postby geeves » Tue May 22, 2018 4:53 pm

Yes and no. Essentially they are the same turbo but the inlet side needs to be turned to fit the intercooler which is not meant to be able to be done on the later turbo but can be if you are careful. The intercooler along with all its brackets bolts straight on as they are the same motor. Only catch is fitting the air scoop and cutting the hole in the bonnet
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 2.8 MU Turbo upgrade options

Postby greegree » Tue May 22, 2018 6:56 pm

Cheers thats awesome. ive just started hearing the deadly noise of a turbo about to die on my truck and have found a replacement of a very low km bighorn thats being wrecked so figured i might take the whole set up and put it on my MU just have to get the angle grinder out
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Tue May 22, 2018 7:03 pm

don't do what I did and cut a hole same size as the scoop. if you can take off the heat shield off the bonnet and have a good plan where to cut the hole
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Re: 2.8 MU Turbo upgrade options

Postby tonkamu » Thu Jun 07, 2018 2:59 pm

Hey guys,

Finished putting on a vf10 with a custom 2.5" downpipe and original Subaru exhaust housing, I was very ignorant how much work was involved doing something different.

turbo1.jpg

turbo2.jpg


I have a question, when I had the exhaust disconnected as I hadn't been to exhaust shop for it to be connected. I was driving around with only the downpipe attached, I was getting amazing turbo sounds. Now that my exhaust is attached it pretty much sounds like my original turbo. Why is that? and is there a way to get those insane turbo sounds back
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Re: 2.8 MU Turbo upgrade options

Postby geeves » Thu Jun 07, 2018 4:58 pm

Straight pipe? Its quiet because the muffler is doing its job. You can fit a more open muffler and get the best compromise between legal noise and nice sound
Sanding your knuckles before starting work can help. That way you cant skin them
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