Stock Psi and pulley size??

23199 Views 11 Replies 10 Participants Last post by Tamra Whitehead, Apr 4, 2017

NORCALSTI

Discussion Starter · Jan 24, 2005

ok for every 1/4 inch smaller on the pully it gets you about 2 psi.

stock lets say 3.50 pulley is 7 psi
3.25 pulley is 9 psi
3.00 pulley is 11 psi
2.75 pulley is 13 psi
2.50 pulley is 15 psi

so if stock is 3.4 and you go to a 2.6 thats .8 difference which will bring up your boost about 6.5 psi from stock

im thinking stock is about 7 psi right?? going to 10 is most i would go before tuning, injectors etc. even 12 psi you can prob get away with. 3.0 pully prob would do the trick if the stock one was 3.5 inches.

anyone know the stock psi for a cobalt ss and pulley size??????

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NORCALSTI

Discussion Starter · #2 · Jan 24, 2005

well got a e mail back from the pulley place i was loooking at here is their reply

"Tony, stock is 3.4" and we offer 3.25" = 1.5lb boost increase, 3.10", 3 lb. boost increase, 3.00" , 4 lb. increase over stock. You will have to change the stock belt, to 1/2" smaller, with any of these sizes. 1 lb. boost is 10 horsepower on these cars. Hope this helps, as also regapping the sparkplugs down .005 setting from stock would be beneficial for optimal performance."

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NIVO88T

· #3 · Jan 24, 2005

12psi is stock boost....Lower boost on S/C then throw a turbo on it.

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Pablo

· #4 · Jan 24, 2005

NIVO88T said:
12psi is stock boost....Lower boost on S/C then throw a turbo on it.

I can't wait to see what psi-fi comes out with

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1BigBird3

· #5 · Jan 24, 2005

NIVO88T said:
12psi is stock boost....Lower boost on S/C then throw a turbo on it.

Never thought I'd do this but I'm pasting this into my sig.

Years ago I would have laughed my ass off at seeing a sticker/decal on a import sporting "TURBO AND SUPERCHARGED!!!!" Now I'm just speechless.

Ruben F.

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87camaroPA

· #6 · Jan 25, 2005 (Edited)

1BigBird3 said:
Never thought I'd do this but I'm pasting this into my sig.

Years ago I would have laughed my ass off at seeing a sticker/decal on a import sporting "TURBO AND SUPERCHARGED!!!!" Now I'm just speechless.

Ruben F.

Yea now that is very possable and i was very surprised when i saw a turbo in a 99 Camaro SS. And it was on the exhaust it was just strainge to see.
There's the site.
http://www.fbodymotorsports.com/chris_s_99_turbo

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NIVO88T

· #7 · Jan 25, 2005

1BigBird3 said:
Never thought I'd do this but I'm pasting this into my sig.

Years ago I would have laughed my ass off at seeing a sticker/decal on a import sporting "TURBO AND SUPERCHARGED!!!!" Now I'm just speechless.

Ruben F.

Funny you would say that, This actually has been done before with some Toyotas running the TRD superchargers.

Also, Nissan did it years ago on their March Super Turbo.

Not a ricer mod at all, you get the best of both worlds, lower boost on supercharge and it takes care of bottom end lag, the turbo gets used to push the limits on top. and bam...you have one powerful machine that people will gawk at...

I actually gave the idea to a buddy that runs a TRD supercharger on his '99 camry.

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Esmond

· #8 · Jan 25, 2005

I talked to the Cobalt SS guy at the Detroit Auto Show, and he said GM purposely put in a larger intercooler to combat knock retard (KR) when people start installing smaller pulleys. I was impressed that GM did this. Shows how much they are paying attention to the intended target market.

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incubi67

· #9 · Feb 8, 2005

oh by the way. that ss with the turbo all they way back by the r.a. that system is by stsit dynos crazy horsepower and is slow as hell . like really bad. they dyno about 550-600 and still only run mid 11's. horrible. the reason why they put it that far back is because the rushing air underneath the car cools the turbo's air by up to 500 degrees so says sts. thus increasing hp as well.. the system still sucks though. i know people with it.

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moonman

· #10 · Feb 10, 2005

i Talked to the guy at the dealer and he said they boost 14 but i dont know for sure i just wont mine to out run my friends srt-4 but he just got stage 2 so i got some work on my hands

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deanh8

· #11 · Feb 16, 2005

NORCALSTI said:
ok for every 1/4 inch smaller on the pully it gets you about 2 psi.

stock lets say 3.50 pulley is 7 psi
3.25 pulley is 9 psi
3.00 pulley is 11 psi
2.75 pulley is 13 psi
2.50 pulley is 15 psi

so if stock is 3.4 and you go to a 2.6 thats .8 difference which will bring up your boost about 6.5 psi from stock

im thinking stock is about 7 psi right?? going to 10 is most i would go before tuning, injectors etc. even 12 psi you can prob get away with. 3.0 pully prob would do the trick if the stock one was 3.5 inches.

anyone know the stock psi for a cobalt ss and pulley size??????

I wouldnt run anything higher then ~9-10 psi without supporting mods.

With intake, exhaust work, colder pulgs, lower thermostat (depending on what the stock one is set at) and maybe even some PCM work should be done before a pulley swap.

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Tamra Whitehead

· #12 · Apr 4, 2017

cobalt ss

Anybody know why my cobalt ss starts to lag and sputter when it rains hard it's like my supercharger don't wanna build boost it normally builds 10 to 12psi but after it stopped raining today and dried out a little it only would build 7 I just bought a new k & n filter just haven't had time to put it on yet any suggestions on why my car is doing that

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