Boost limit?

[Si|ver Bu||et]

I was just reading another thread and remembered how everybody always talks about their boost going into the red zone.

I was wondering if it does that stock or is that modified, because mine only goes to the boundry of the yellow, and never enters the red

[Robinb]

Stock allows very little opportunity for getting into the broken red, never mind the solid red.

That's where the low-cost MBC comes in - you can add another 3-4 psi of boost without too much danger of fuel cutout, and begin to creep into solid red.

[Stefano]

Originally Posted by Si|ver Bu||et

mine only goes to the boundry of the yellow, and never enters the red

Are you sure you're not stuck in base boost? disconnect the electrical connector on the BPC solenoid and see if the boost is lower or not. If not, you're in base boost.

[Si|ver Bu||et]

oh ok, thanks, but isnt it bad to run in the red??
doesnt red usually mean

[Si|ver Bu||et]

and is it bad to be running it more than base boost? doesnt red usually mean bad? lol

[Stefano]

Base boost is a boost level that is there for safety reasons. If everything else fails, APC or Trionic will lower boost to base boost. So, running more than base boost is only normal.

[Si|ver Bu||et]

so happy now , just need to get a new clutch first.

so basically I can adjust the boost to high number, 8 or 9 PSI, and then disconnect the APC solenoid valve and drive around on base boost like that. and then when I want the high boost just connect the APC solenoid valve???

[djtaylor]

Why would you want to do that? How's that going to work? You want to overtake someone so you pull over, get out, connect the APC valve and then carry on?

There's nothing to gain from what you've described because max boost will be controlled by the APC valve and if your base boost is too high to start with, it doesn't reach max boost.

Have you stuck a calibrated boost gauge on your car? Mine goes to the boundary of yellow/red at around 1 bar boost. Your car sounds normal to me.

David.

[Si|ver Bu||et]

I was thinking that when its disconnected its running base boost, which is the same that I am running now, which is enough if I want to overtake...

[djtaylor]

How do you know you're running base boost? Have you stuck a calibrated boost gauge on yet?

[Si|ver Bu||et]

I unplugged the power to the APC solenoid, and I realised that when it runs base boost, it runs it in the middle of the yellow. Then when I plug it in it runs right up to the red, but still in the yellow (boundry of yellow). So if I up my base boost to where my max boost is now, then my max boost will be higher??

[djtaylor]

The APC mechanism is automatic, it's not a system that adds xx boost from the base position so by turning base boost to what you have as max boost right now, all that will happen is that the APC system will keep the valve open, you'll achieve nothing.

As I said before, mine puts the turbo gauge on the boundary between yellow/red at full boost, I know this because I have a second boost gauge fitted, mainly because i'm tall and can't see the one on the dash because it is blocked by the top of the steering wheel.

Conclusion - your car is normal, nothing to worry about, you don't sound like your losing anything. If you want to boost higher, then you'll need to modify other areas like the ECU or if you must, add an MBC.

David.

[Si|ver Bu||et]

thanx...
yea I guess but I would like to have more boost...and the only way is with an ECU or MBC? and what is an MBC?

[djtaylor]

MBC = Manual Boost Control

You set the boost (using a calibrated boost gauge of course) and turn it up as high as you like. Once you've melted the pistons, you can back it off a little. Can you see the problem with this method?

The A in APC is AUTOMATIC, if too lean a mixture is determined and engine knock occurs, the APC along with trionic will back off the ignition timing and reduce boost to a safe level.

Saab put a lot of effort into making APC and trionic a reliable system for everyday use while delivering useable power. By all means fit an MBC but understand that you're removing all the nice protection that Saab built in for you.

The ECU upgrade is usually considered the better solution.

David.

[Si|ver Bu||et]

alright thanx....

an aftermarket ECU will still run more boost safely right? The APC and ECU will work together to protect it but still (relatively)safely run more boost?