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BC5 EJ20g Boost spike/cut


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#1 Rex Calibvr

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Posted 10 August 2019 - 2:41 AM

Hey all

 

Hoping someone can help, wanting to increase boost to 14/15psi, i can get this with an MBC, but 4th gear boost spikes too high and it will cut, its at about 1.2bar or 17psi (my gauge only reads to 1.1).

I have the MBC between the stock boost control and wastegate actuator.

 

Can i remove the factory boost control with no effect on computer?

How can i best eliminate boost spike so i can i can run boost smoothly?

 

It has high flow panel filter & 2 3/4 exhaust with siamese downpipe.

 

 

Just want that little bit more from the engine without taking it too far from stock.

 

Any help, ideas or wisdom would be greatly appreciated.

 

Thanks heaps



#2 DCVR

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Posted 10 August 2019 - 4:01 AM

Hey all

 

Hoping someone can help, wanting to increase boost to 14/15psi, i can get this with an MBC, but 4th gear boost spikes too high and it will cut, its at about 1.2bar or 17psi (my gauge only reads to 1.1).

I have the MBC between the stock boost control and wastegate actuator.

 

Can i remove the factory boost control with no effect on computer?

How can i best eliminate boost spike so i can i can run boost smoothly?

 

It has high flow panel filter & 2 3/4 exhaust with siamese downpipe.

 

 

Just want that little bit more from the engine without taking it too far from stock.

 

Any help, ideas or wisdom would be greatly appreciated.

 

Thanks heaps

 

Hi have a quick search on the forums I'm sure there's a walkthru somewhere showing exactly how the plumbing goes.  Also found this link which might be useful

 

https://www.clubwrx....noid.134349063/

 

also, what kind of mcb u using?  some of them are just rubbish


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#3 Rex Calibvr

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Posted 10 August 2019 - 4:15 AM

Its a tee with ball and spring and seperate needle valve to vent to atmosphare.

Will check out the link now.

Thanks

 

So basically reading that link, i should just leave it and wait until i can get an aftermarket ecu and tune it to 14psi on dyno?



#4 DacerX

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Posted 10 August 2019 - 5:07 AM

I was about to say get a link before your engine loses the will to run or compression whichever comes first, may the odds be ever in your favour
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#5 Rex Calibvr

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Posted 10 August 2019 - 5:31 AM

Isn't it safe to run 14psi on these engines?
It's just the spike that's the issue, which I believe happens from factory, spikes 14/15 & drops back to 11.

I may be completely wrong, trying to educate myself, but distinguishing correct info can be hard

#6 DCVR

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Posted 10 August 2019 - 6:50 AM

there's lots of conflicting info.  Yes the engines are good for 14psi but just keep in mind they only came out at 8psi so depending on how they're being driven the wear and stress factor goes up accordingly. Ideally you would get a tune to dial everything in correctly but you'd need an aftermarket ecu for that.  

 

google 'subaru legacy boost controller delete' or 'boost solenoid delete' or try mixing up your search words.

 

RSLiberty is also another good forum

 

You could also try posting on the DOBC group FB page if ur not on it already

https://www.facebook...00340879977390/

 

Subaru Parts NZ https://www.facebook...00340879977390/

 

wots ur FB name?


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#7 Rex Calibvr

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Posted 10 August 2019 - 7:03 PM

Thanks man.
Factory boost is 11... but yea I got you.

I'm not a fan of dirty ol Facebook, but I did start another acc when I bought the legacy.
It's under the same pseudo as this Rex Calibvr, otherwise known as Daniel.... along with various nick names.

I'll have another Google today, but I will get an ECU and do it properly.

Any other basic upgrades you guys would recommend?
Remembering I want to keep it looking pretty close to stock.

Thanks

#8 DCVR

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Posted 10 August 2019 - 9:08 PM

Thanks man.
Factory boost is 11... but yea I got you.

I'm not a fan of dirty ol Facebook, but I did start another acc when I bought the legacy.
It's under the same pseudo as this Rex Calibvr, otherwise known as Daniel.... along with various nick names.

I'll have another Google today, but I will get an ECU and do it properly.

Any other basic upgrades you guys would recommend?
Remembering I want to keep it looking pretty close to stock.

Thanks

 

there's just so much you can do to the RS/BF depending on where you wana take it.  Braking mods are worth while and needn't be expensive.  


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#9 Rex Calibvr

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Posted 10 August 2019 - 11:16 PM

Yea I will look at brakes at some stage. Mainly fixing small things atm, (air leaks around doors noises, adding catch can, blown speaker etc.)

It rides abit hard, rear shocks have been compressed, front is lowered. So might fit coilovers. Also might mod exhaust to remove highway drone and to look more stock.

Plenty to do, just need info and $$$ lol.
But it will get there

#10 DCVR

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Posted 11 August 2019 - 7:17 PM

take your time.  There's so much that can be done to these old girls while still keeping the factory look


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#11 Rex Calibvr

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Posted 12 August 2019 - 6:49 PM

That's what I'm after.
I accidentally cracked the engine cover :(
Was being so careful too. Doubt anyone would have a spare.

And yea I'll take my time, and alot of research.

Thanks




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