10-12psi boost?

elkaboom · Post by **elkaboom** » Fri Jul 16, 2004 4:33 am

Okay, I'm at a bit of a disadvantage here, but I was having a discussion last night with a friend about the boost capacity of a stock sport sedan.
Without any resources to fact check, I was relying on memory -I was pretty sure the stock setup runs at 8-9psi, though, right?
Being the owner of an n/a, my knowledge of things turbcharged on Subarus is sketchy at best, but what specifically (in terms of engine and engine control management) would be neccessary to run at 10-12psi consistently?
The numbers are kind of arbitrary, but we were just waxing philosophical.
Any ideas? Cost to achieve? Relative difficulty?

georryan · Post by **georryan** » Fri Jul 16, 2004 4:36 am

Well it depends on what elevation you are really. The ecu allows enough boost to acheive a certain level of pressure to the manifold. In higher elevations it raises the boost, and in close to sea level it is about 8.7 psi reletively.

If you want to raise it you can do that with a cheap manual boost controller. If the ecu sees 13 psi of boost for more than 3 seconds (right?) it will cut the fuel, unless you have a fuel cut defender of some sort.

legacy92ej22t · Post by **legacy92ej22t** » Fri Jul 16, 2004 5:11 am

If you got a Saab 900 TMIC setup with a MBC, you could run 11-12 psi all day long without any worries.
Because most MBC's don't hold boost real well though you still may get FC when boost spikes so I'd install a FCD just to be safe (and safe yourself from a sore neck).

Georryan's got it. IIRC, FC will happen at 27.5 psi total pressure (atmospheric pressure + manifold pressure) for more then 3 second, so elevation does make a difference but at sea level it's 13 psi at the manifold.

mTk · Post by **mTk** » Fri Jul 16, 2004 7:11 am

You can run 10-12psi all day long on the stock motor. I've been doing this for some time now.

MK

BAC5.2 · Post by **BAC5.2** » Fri Jul 16, 2004 9:45 am

I ran 12psi, with my SAAB TMIC, and stock exhaust.

It wasn't ideal, I'd probably have been faster on 10psi, but I ran 12 psi for about a week. Then in went the exhaust, and up went the boost to 15.

I usually just do part-throttle pulls @10psi since my FCD is non-functional at the moment.

91White-T · Post by **91White-T** » Fri Jul 16, 2004 4:32 pm

elkaboom wrote:but what specifically (in terms of engine and engine control management) would be neccessary to run at 10-12psi consistently?

absolutely nothing except a boost controller

BAC5.2 · Post by **BAC5.2** » Sat Jul 17, 2004 10:19 am

It's a good idea to have at the very least an intercooler if you live at sea-level.

elkaboom · Post by **elkaboom** » Sat Jul 17, 2004 4:09 pm

Alright then, here's another question: how exactely does a a manual boost controller work?
Is it an electronic device that overrides the ECU's predetermined settings?
How is it attached?

THAWA · Post by **THAWA** » Sat Jul 17, 2004 5:10 pm

nope, it would be an electronic boost contorller if it did that. It goes inline where the stock boost controller was, between the wastegate and compressor inlet. Instead of using the stock solenoid to bleed pressure at 8.7 psi (electronically), it will allow you to adjust what pressure the wastegate starts bleeding pressure (mechanically).

Here's an example of one you can build: http://www.autospeed.com/cms/article.html?&A=0096

Gonzoturbo · Post by **Gonzoturbo** » Sat Jul 17, 2004 8:48 pm

2 Questions. This seems an appropriate thread.

1. What is the advantage of the coffee mug?

2. Where can I get or make a FDC?

legacy92ej22t · Post by **legacy92ej22t** » Sat Jul 17, 2004 8:58 pm

The coffee cup mod replaces the very restrictive resonator that's inbetween the air filter box and the turbo in the stock intake.

FDC? Do you mean MBC (manual boost controller) or FCD (fuel cut defender) ?

444turbo · Post by **444turbo** » Sun Jul 18, 2004 12:08 am

15 PSI all day long...

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10-12psi boost?

10-12psi boost?

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