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Old 06-12-2012, 08:19 PM   #1
PQ
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Drives: 2010 Supercharged SS
Join Date: Apr 2008
Location: Mobile, AL
Posts: 36,717
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Pulley 101 .......info for dummies like me

So, recently I discovered kinda what I suspected for a while........

My 2.8" pulley on the front of my Maggie ideally should be creating around 11-12 pounds of boost and not 8.

I have had my TVS2300 Magnacharger on my car for a long time now. LOVE it. But it never sat well with me that I am running such a small pulley to only get an 8-8.5 psi average through a dyno pull.

Now to be accurate, I am running a 3.2 inch pulley on it with my daily driving. Keeps me safe as far as boost goes and the 2.8 is not needed for the street anyway imo. I can throw the 2.8 on in 5 minutes if I want to go to the strip or have some fun.

But the 2.8" pulley produced an average of 8 pounds on the dyno and the 3.2 produced an average of 6 pounds. (see bottom two dyno graphs) Before my cam I had dynoed the car with a 3.6" pulley to a 7-8 pound average. I know I lose some adding a cam and I still have to get my cam specs but it's a mild cam and I can't see losing THAT much boost.

So now I'm going to be buying an OD cog drive for the back and getting a boost gauge so I can see what size pulley will net me an 8 pound average.

Now my ultimate question that drove me to create this thread is what the hell is the point of 6 rib 3.2 down to 2.8 pulleys if they can't pull solid and they slip so badly?

I mean that's some seriously shitty belt slippage to lose so much boost. I just don't feel comfortable with my car tuned for a level based on a slipping belt.

What if the belt decides one sticky day that it wants to grab for a minute? BOOM............... right?

Or is that not possible?

I may need a fuel rail or cut my existing fuel rail but I am going to get a rear OD Cog drive so I can take care of this but WTF? Why the hell are they selling these pulleys if they don't work?



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