Garage Storage Organization and Garage Cabinets

Scotty · **M90 Supercharger**

Stock boost on the M90s that came in the Thunderbirds is 12 PSI. Less on the GTP? Besides finding a larger pulley to reduce the boost to approximately 5 PSI, is there any other way to lower the boost from this supercharger?

If not, where could one even begin to find a larger pulley to fit the M90s. I have a feeling smaller ones are in abundance because generally people want to increase, not decrease performance.

**speedyshelby16** · 01-30-2006, 01:39 AM

The larger the pully then less boost your going to have. smaller pullys spins more hence making more boost.

Scotty · 01-30-2006, 01:45 AM

Yes sorry. I dont know why I confused the two. I was just coming back to edit the post when I realized.

LOL.

Scotty · 01-30-2006, 01:46 AM

And I am curious if the M90 off of a GTP would be better because it has a larger pulley to begin with?

**speedyshelby16** · 02:12 AM

I found this on the internet about gtp psi and pully size.

Here were I found the info. http://www.grandprix.net/faq/

If a smaller pulley than 3.8 inches is used, you increase the rate at which the pulley turns and thus increase the compression of the air that's taking place inside your supercharger, called boost. Your stock pulley will translate into a maximum of about 7.5 to 8 pounds per square inch (psi) of boost, whereas a 3.5" pulley will increase that to over 11 psi of boost. In terms of power output you can expect around 30 more horsepower and at least the same amount of torque, a noticeable difference in power.