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Discussion Starter #1
IS the boost at 1st and secound 9 psi and the rest its 13.5psi?and if so can i set all of them at 16? with a MBC?? and would it be safe?
 

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Pre MBC on my MY01 WRX:

1st = 9-12 (12 near redline)
2nd = 15
3rd = 15
4th = 15
5th = 15

Post MBC:

15 in all gears from 3,000rpm

Michael
 

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i dont know how you set an mbc. so how do you set boost at each gear if you adjust the boost by just turning a lil screw?
 

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Are you sure on those numbers michaelwrx?

My numbers are a bit like pace's. when i'm in 1st and my BC is set to 16.5psi, i get about 14-14.5psi.

and also is that right? a 01' rex gave 15psi in every gear (except first) before a BC?? maybe i should've bought the '01 rex! hehe.

---RaCinWRX
 

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Oh yes, and answer to the original first question.
To revinwrx: i hear setting it to 16.5psi for races is even ok, but 17 would be pushing it. Although for daily driving with an MBC, ppl are almost unanimous in their setting of 15psi.

To Jdmario: umm i never thought to question why this screw controlled whether or not more psi comes out or not. i just know to turn it this way for more.. that way for less <g>

---doesn't know anything about MBC's, RaCinWRX
 

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stock, I had
~9
12
14.5
14.5
14.5
18psi in reverse :eek: j/k

I just leave my MBC at 17psi. It goes down to 14.5-15psi at redline anyway, but has 17 in the midrange like it should. There is plenty of fuel there, but that's about as high as you can go without losing power (and making so much heat).

Also, you can never get full boost in first. There isn't enough loud there. You can put your mbc fully closed and only get ~16psi in first, but in 2nd you'll get over 20psi.

hth, -C
 

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Discussion Starter #8
OK I HAVE A BOOST GAUGE in mpa but i know how to convert it to psi so should i set my psi nto 15.5? and if it says so on the boost gaige then it is 15.5 my car is curreently runnin 13.5 i have a 2002 WRX so when im drivin i should test how much psi im at in 3rd gear and that means 1st will be like 9-13 right and the rest will be 15.5????i dont know how u peoiple r sayin u set diffrent psi at diffrent gears how is that possible on a MBC??
 

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It's not really possible to set different boost levels in different gears. A standard MBC has a single adjustment screw. However, it is a simple fact that your WRX builds boost as the motor is placed under load. This means you are going to see the most boost in fifth gear, and the least in 1st. Most people find that the psi difference across 3rd - 5th is much smaller than the difference across 1st - 3rd, which is why we calibrate for 3rd, 4th, or 5th gear. I personally calibrated at 15psi in 4th gear. This translates to the occasional spike to 15.5psi in 5th gear in cold weather, and a maximum of 13psi in 1st gear. Everyone with a MY02 USDM WRX with a MBC will tell you basically the same thing.

Under 'normal' driving conditions you WILL NOT get the same level of boost in 1st as you do in 5th, with a manual boost controller.

-Pace
 

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personally when i'm calibrating for a 1/4 mile race. i calibrate the BC in 3rd gear.

but if i'm going for say a longer race. i calibrate my BC for 4th or even 5th gear.

---hoping all this makes a wierd kinda sense, RaCinWRX
 

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RaCinWRX said:
Are you sure on those numbers michaelwrx?

My numbers are a bit like pace's. when i'm in 1st and my BC is set to 16.5psi, i get about 14-14.5psi.

and also is that right? a 01' rex gave 15psi in every gear (except first) before a BC?? maybe i should've bought the '01 rex! hehe.

---RaCinWRX
Ok...I have rigged up a permanent boost guage and report the following with MBC

1st = 13 psi
2nd & 3rd = 14.5 (peak) settling back to 14 almost instantly
4th = 14 (under load 14.5)
5th =14.75 under WOT


Michael
 
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