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The mkiv Supra Owners Club

MBC set to lowest and boosting to 20psi on standard twins


Shaleskin

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Got some replacement standard turbo's from Dom1993 (SupraLee's old turbos) and now managed to fix the issue of it boosting at 2psi. It's set to the lowest it will go and yet when i reach 5k revs it's boosting up to 20psi. I've got a 2.5" pipe in replacement to the cat, then 3" back Blitz Nur Spec.

 

Is it just the turbo's that can't take more than 1.2bar or is it that it can't be fueled for on the standard injectors?

 

As if it's fueling I've got 650cc's running on a hardwired e-manage piggy back if that makes any difference? :rolleyes:

 

Any input would be great! :friends:

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J-Spec turbo's generally don't like anymore than 1.2 bar. Have you got a restrictor ring?

 

In all honestly I don't know, I'd assume not if it's peaking past 1/1.2bar. Although I thought the restrictor ring size was 2.5" so having the 2.5" downpipe would've done it?

 

What size ring would be ideal?

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You need to remove the mbc, and throw it in the bin. Then run without a boost controller and see what you're getting. Then buy a quality EBC :)

J spec turbos have been known to throw their turbines down the exhaust at anything over 1.1bar.

 

Aw but it's a turbosmart Hi & low boost setting MBC :innocent:

 

I thought 1.2bar was OK for these to be ran at?

 

Where's the best place to buy a 2" restrictor then? Had a quick look on fleabay and found 2.5" and that's it...

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Aw but it's a turbosmart Hi & low boost setting MBC :innocent:

 

I thought 1.2bar was OK for these to be ran at?

 

Where's the best place to buy a 2" restrictor then? Had a quick look on fleabay and found 2.5" and that's it...

 

That doesn't sound like an MBC to me. Are you sure about it being manual and not electronic? How does the "hi and low" setting work?

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That doesn't sound like an MBC to me. Are you sure about it being manual and not electronic? How does the "hi and low" setting work?

 

Yeah definitely manual, it's got 2 dial knobs in one device block which has wires going to a fighter style toggle switch to flick between the two. I'll get a pic shortly.

 

Also, whoever's plumbed the BC up has taken the boost reading from the boost pipe going to the intercooler oppose from the nipple coming off the turbo housing. I assume this wouldn't make much of a difference as it's still being pressurized? (will get a pic of that too)

 

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Edited by Shaleskin
Pictures! (see edit history)
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There is a chance that you already.have a ring but you keep hitting this boost..j spec are know for.overboosting a bit..check your air/fuel ratio and if you car its.mapped ok.you will.be fine..i.have.been running.1.2 for the last 10.years and its all good..

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Yeah definitely manual, it's got 2 dial knobs in one device block which has wires going to a fighter style toggle switch to flick between the two. I'll get a pic shortly.

 

Also, whoever's plumbed the BC up has taken the boost reading from the boost pipe going to the intercooler oppose from the nipple coming off the turbo housing. I assume this wouldn't make much of a difference as it's still being pressurized? (will get a pic of that too)

 

[ATTACH=CONFIG]199875[/ATTACH]

 

[ATTACH=CONFIG]199876[/ATTACH]

 

[ATTACH=CONFIG]199877[/ATTACH]

 

That's nuts :D

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