Increasing boost
06-13-2001, 08:34 PM
#1
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Increasing boost
I've heard on various occasions that it is possible to run a 931 upto 15 psi bosst instead of the stock 10. I would like to consider this but I'm unsure of how. I've had a quick look at everything from 1.0 bar springs upto electronic boost controllers and other things inbetween. Does anyone have any experience with this? Thanks in advance.
06-15-2001, 04:06 PM
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Hi Brad, the spring way is probably the least versatile out of all of the ways, i would go with a controller, it just depends on how much $$$mOnEy$$$ you want to spend.
On hot summer days 15PSI is probably too much for the engine to handle heat wise without some sort of cooling, water injection and/or intercooling etc..
There are simple controllers and fancy controllers, in cockpit and out of cockpit, i guess its the money that is the deciding factor, a simpel manual controller works fine, but the more expensive ones let you store boost more effeciently, the wastegate doesn't lose any turbo pressure until you want it to, i think you can program the expensive ones, whereas with a manual simple one you don't get to program WHEN you want the wastegate to start to open, and it isn't VARIABLE at different times. (IE you want the wastegate completely closed at 1500 RPM say, so with a manual controller it will always be open a little, just like stock, but with the expensive controller you can program it to start opening at 2200 RPM or whatever, its not based upon RPMS, but a t certain rpms there is a certain pressure built)
On hot summer days 15PSI is probably too much for the engine to handle heat wise without some sort of cooling, water injection and/or intercooling etc..
There are simple controllers and fancy controllers, in cockpit and out of cockpit, i guess its the money that is the deciding factor, a simpel manual controller works fine, but the more expensive ones let you store boost more effeciently, the wastegate doesn't lose any turbo pressure until you want it to, i think you can program the expensive ones, whereas with a manual simple one you don't get to program WHEN you want the wastegate to start to open, and it isn't VARIABLE at different times. (IE you want the wastegate completely closed at 1500 RPM say, so with a manual controller it will always be open a little, just like stock, but with the expensive controller you can program it to start opening at 2200 RPM or whatever, its not based upon RPMS, but a t certain rpms there is a certain pressure built)
06-16-2001, 11:48 AM
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Yeah, they have some really neat digital toys out there... too bad they're all mostly designed for EFI cars...
Looking through the APEXi site (www.apexi.com) they did have some older, less expensive boost controllers that looked like they might be a good value for a CIS car... under $300...
Looking through the APEXi site (www.apexi.com) they did have some older, less expensive boost controllers that looked like they might be a good value for a CIS car... under $300...
06-17-2001, 12:24 AM
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I figure that at 25 degrees Celsius at 15 psi boost I'll be just short of EGT's that promote knock. If I switch to premium I should be allright upto 30 degrees. I hope. Any hotter and I'll just have to take it easy. Anyway, how do the manual boost controllers work? Plug'em in the vent line and turn a ****??
06-17-2001, 09:59 AM
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That's pretty much it, as I recall. You do absolutely need a boost gauge of course. You also need to drive the car to develop max boost in order to determine what it's set at. It's also "dumb" - boost adjusted to 15psi on one day could easily creep higher under different atmospheric conditions, say winter vs. summer. Need to keep an eye on it.
06-19-2001, 01:16 AM
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Just so I am following everyone correctly. The air flow adjuster **** would be spliced into the line that runs from the bypass valve to the pressure tube? Is this the vent line that everyone is talking about?
06-19-2001, 01:54 AM
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Originally posted by PAH924:
<STRONG>Just so I am following everyone correctly. The air flow adjuster **** would be spliced into the line that runs from the bypass valve to the pressure tube? Is this the vent line that everyone is talking about?
</STRONG>
<STRONG>Just so I am following everyone correctly. The air flow adjuster **** would be spliced into the line that runs from the bypass valve to the pressure tube? Is this the vent line that everyone is talking about?
</STRONG>
Pah, hi, its the one directly across from the pressure cut off fuel switch, its the wastegate line.
Goes right inbetween the aluminum duct that says "924 turbo" on it and the wastegate line, black hose with spindle nut connection.