How much boost?/Ground Control Coilovers Good?
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How much boost?/Ground Control Coilovers Good?
I was wondering how much boost I can run if I'm stock except a BOV and MBC. I have heard there is a fuel cutoff for boost in excess of 17psi. Is this true? Is there an easy way around that? If I were to turn up the boost above stock, what would be a pretty good amount of HP to expect for each additional PSI?
I was also wondering if Ground Control coilovers are good on WRX's. I realize there are very expensive setups out there, but for 300 dollars it seems they cant be beat. Lemme know your opinions please. Maybe even let me know which drop springs you like the best. I want an overall lowered look, but I want to be able to take the car in the snow and stuff.
Thanx alot!
I was also wondering if Ground Control coilovers are good on WRX's. I realize there are very expensive setups out there, but for 300 dollars it seems they cant be beat. Lemme know your opinions please. Maybe even let me know which drop springs you like the best. I want an overall lowered look, but I want to be able to take the car in the snow and stuff.
Thanx alot!
Last edited by SSFWRX; Dec 16, 2002 at 02:46 PM.
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The stock turbo is performing optimally at 15 PSI. 15 pounds is safe. You gain good power up to there from stock, then after 16 the turbo is out of it's efficiency range and you start to generate to much heat this can cause engine destroying knock. To run more boost efficently you would need a different turbo charger and possibly better cooling for the charge like a bigger intercooler. Aftermarket turbos range in price from 700-2000 dollars, I recomend a slightly larger ceramic ball bearing turbo. At higher boost you also need to worry about fueling and knock. So a fuel controller or aftermarket ECU would be in order so you don't blow up your motor.
The right parts for the right application are cheaper then a fried motor.
You might consider making more power with full exhaust, intercooler and hoses, intake, under-driven or lightened pulleys.
You don't want to get a coilover spring kit. That uses your stock struts with some coilver springs. The car will handle/ride better getting some HR springs($275), even with the stock struts. Use KYB AGX struts if you can($459), you'll be ready for the track then! We always want to help.
The right parts for the right application are cheaper then a fried motor.
You might consider making more power with full exhaust, intercooler and hoses, intake, under-driven or lightened pulleys.
You don't want to get a coilover spring kit. That uses your stock struts with some coilver springs. The car will handle/ride better getting some HR springs($275), even with the stock struts. Use KYB AGX struts if you can($459), you'll be ready for the track then! We always want to help.
Last edited by RalliTeK; Dec 16, 2002 at 07:26 PM.
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Joined: Nov 2002
Posts: 735
From: Bay Area
Car Info: 2002 MBP WRX, 2012 OBP STi wagon
hey, SSFWRX. Where in South City are you?! WHY haven't you shown up at the San Bruno Starbuck's meets or the Daly City Krispy Kreme meets, or even the Tapioca Tea meet at Eggettes we had last week?! 
If you want some modding advice, show up. We've got all ranges of mods, from totally stock up to full Vishnu Stage 2+ upgrades, coilovers, body kits, lights, etc. Next meet is this Friday, 7PM, at the Daly City Krispy Kreme. We also meet Mondays at the San Bruno Starbuck's in the Bayhill Shopping Center, just north of Tanforan, at 7PM. You're in the area, might as well drop by.
As far as your questions:
The stock turbo is out of its efficiency range at around 17 psi. After that, you'll hit fuel cut, you'll generate more heat than boost, and the turbo won't be effective at all. Max safe PSI is around 15.5-16. If you have an MBC, watch out for partial throttle high boost situations, where your boost is very high (over 66%) but your throttle is not engaged more than a third to a half open. This generates high EGTs, and can fry your cat, sending chunks into your turbo, making that turbo replacement/upgrade MANDATORY. Just remember to either back off or punch it when you see PTHB situations and you will be fine, OR get a better up-pipe. Another way around this is to get an S-AFC or anything that can tweak your air/fuel maps.
The WRX is a small engine with a small turbo. To really get good performance, you have to open up the airway and let the engine breathe more. Check out the various tuners out there (Cobb, TXS, Vishnu Performance Tuning, etc. (Vishnu is local in the Bay Area)) to see what kind of modifications are available to you. There used to be only one way to get really good performance out of the WRX: the unichip. There are quite a few more options available to you now, so look around. Shiv at Vishnu Performance has dynoed stock WRXs on his AWD dyno at around 160-180whp. Adding an MBC can change this, but there is no way to accurately say "adding this much PSI will net you this much boost" since every car is different. The only way to tell is after you dyno tune your car. Some people have reported little gain with an MBC, some have reports relatively large gains. YMMV.
Also, if you want a more "local" response, start posting in the Bay Area forums, and those of us local to you can respond to your specific needs, etc. After all, not all people in other states understand that California is octane limited to 91, nor do some tuners take this into account.
See you at the local meets .
shadowcat
If you want some modding advice, show up. We've got all ranges of mods, from totally stock up to full Vishnu Stage 2+ upgrades, coilovers, body kits, lights, etc. Next meet is this Friday, 7PM, at the Daly City Krispy Kreme. We also meet Mondays at the San Bruno Starbuck's in the Bayhill Shopping Center, just north of Tanforan, at 7PM. You're in the area, might as well drop by.As far as your questions:
The stock turbo is out of its efficiency range at around 17 psi. After that, you'll hit fuel cut, you'll generate more heat than boost, and the turbo won't be effective at all. Max safe PSI is around 15.5-16. If you have an MBC, watch out for partial throttle high boost situations, where your boost is very high (over 66%) but your throttle is not engaged more than a third to a half open. This generates high EGTs, and can fry your cat, sending chunks into your turbo, making that turbo replacement/upgrade MANDATORY. Just remember to either back off or punch it when you see PTHB situations and you will be fine, OR get a better up-pipe. Another way around this is to get an S-AFC or anything that can tweak your air/fuel maps.
The WRX is a small engine with a small turbo. To really get good performance, you have to open up the airway and let the engine breathe more. Check out the various tuners out there (Cobb, TXS, Vishnu Performance Tuning, etc. (Vishnu is local in the Bay Area)) to see what kind of modifications are available to you. There used to be only one way to get really good performance out of the WRX: the unichip. There are quite a few more options available to you now, so look around. Shiv at Vishnu Performance has dynoed stock WRXs on his AWD dyno at around 160-180whp. Adding an MBC can change this, but there is no way to accurately say "adding this much PSI will net you this much boost" since every car is different. The only way to tell is after you dyno tune your car. Some people have reported little gain with an MBC, some have reports relatively large gains. YMMV.
Also, if you want a more "local" response, start posting in the Bay Area forums, and those of us local to you can respond to your specific needs, etc. After all, not all people in other states understand that California is octane limited to 91, nor do some tuners take this into account.
See you at the local meets
.shadowcat
Last edited by shadowcat; Dec 17, 2002 at 06:08 AM.
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