Whats the Stock Max boost?

[GreenChevelleSS]

What is the stock max boost that these things come with from the factory? 90 7MGTE

Well Im getting 5-6PSI boost :icon_bigg with the bypass valve stuck open... so what do you think it would be with a new one in place? I havent done anything to up the boost except i had the block and head decked...

 

[Joel W.]

i think its 6.8psi off the top of my head? no clue once you fix the bov. probably stay the same...

 

[GreenChevelleSS]

Why would it stay the same when its leaking off the boost?

 

[Joel W.]

i would think the turbo would work harder to maintain 6psi with a leak. so once the leak is fixed it will still be 6+ untill you use a boost controller or washers to up the boost.. and the turbo wont have to work as hard...

 

[GreenChevelleSS]

what does a boost controller do?

 

[Joel W.]

well, there are a few different kinds, electronic and manual controllers and basically, both allow you to adjust your boost over stock psi.

edit, search for MBC and EBC
http://www.supramania.com/forums/forumdisplay.php?f=42

 

[shaeff]

chances are: your boost will stay the same, but it'll come on a bit earlier as the turbo is working harder since it's leaking off the boost.

-shaeff

 

[rakkasan]

what does a boost controller do?

control the boost. :naughty:

 

[7MGTEJoe]

what does a boost controller do?

It manipulates the pressure signal that the wastegate actuator "sees". The stock spring/diaphragm assembly opens the wastegate when it sees ~6.8 psi (taken off the inlet track). A boost controller diverts this pressure so you can run more boost before the wastegate opens. Stock boost "max" is around 12 psi; more than that and you'll hit fuel cut. I said "around" 12 psi becuase fuel cut is based off of the MAF signal not manifold pressure so atmospheric conditions give it a bit of play.

 

[Supra5MGTE]

the hose going from the 3000 pipe to the BOV was all dry roted and had a HUGE leak in it. got 7PSI? on the stock gauge and put new hoses on the BOV and checked for other intake leaks... still the same psi now. but it starts and idles better and i'm sure gas milage is better.

 

[boost fiend]

i agree with shaeff. either put another valve in or go aftermarket bov. dont over work the turbo. but on the other hand, it could be argued that the boost leak *could* help with spool up time. as far as stock boost i beleive its about 8 psi.

 

[shaeff]

The stock spring/diaphragm assembly opens the wastegate when it sees ~6.8 psi (taken off the inlet track).

almost, but in reality, the wastegate starts opening when you hit positive pressure. it's FULLY open at 6.8psi. if you want EVEN BETTER spool up time, get an electronic boost controller, as it will keep the wastegate COMPLETELY closed until your desired boost setting. by far, the best way to go.

even with a manual boost controller, the wastegate STILL starts to open before full boost is reached because it acts as a bleeder valve.

-shaeff

 

[tlo86]

4 PSI in colorado 6-7 psi in texas

 

[boost fiend]

again, shaeff has the point. i HAD a hks electronic valve controler and it was great. too bad i decided to sell it. they do do a much better job than a mbc. spend a few bucks and enjoy the ride!!! :icon_evil

 

[Anh]

almost, but in reality, the wastegate starts opening when you hit positive pressure. it's FULLY open at 6.8psi. if you want EVEN BETTER spool up time, get an electronic boost controller, as it will keep the wastegate COMPLETELY closed until your desired boost setting. by far, the best way to go.

even with a manual boost controller, the wastegate STILL starts to open before full boost is reached because it acts as a bleeder valve.

-shaeff

Some good points there. "Stock boost" assumes people are still using the restrictive stock exhaust system, elbow and downpipe. When people see gains in boost by upgrading the exhuast, it's difficult to be sure what boost the standard actuator is rated as.

 

[billspreston01]

At one point I wasn't getting any boost, the gauge didn't move AT ALL at any rpm. I was tooling around fixing some things in the engine, too the stock bov and blew threw it.....no resistance at all. Grabbed the bov from my 87 blew into it...couldn't do it. Slapped the 87 working bov on...maxxed the stock gauge. Just fix the problem, regardless of if you're going to get more boost or not.