Need help with supercharger pulley sizes

[djcontra]

I've got a custom charger on my car, and right now it's running low boost because I had many other things to get for the car before I bump it up any further (including ecu software).
Now that I've got everything ready, I need some help deciding on pulleys, and vortech isn't exactly swift in getting back to me with my questions...

I've got right now a 6.66" crank pulley on my m50 with a 3.70" supercharger pulley. I'm using a Vortech V-9 Gtrim unit, and I believe it's running at something small like 4 psi right now. What would be the ideal pulley size combination for me to buy from vortech to get anywhere from 9 to 11 psi?

I'd prefer only to have to buy one replacement pulley, but if you feel I should replace both to different sizes, please enlighten me.

thanks!

[Scho]

The RMS 6" pulley delivers 11 psi I believe.

[djcontra]

Yeah I read that too, 6" crank + 3.33" s/c is what I was reading on this forum in past threads.
Doing some math (which i most likely got wrong mind you ), I figured that if I were to get a 3.33" pulley for my supercharger, I would get 12psi of boost out of my charger, but I'm not sure if running a combination like that would be safe (for my engine, charger, and belt, stress-wise)

Also, if I get the 3.33" pulley, and don't want to run the full 12psi of boost, can I install an adjustable BOV to release pressure at let's say 10psi, and just tune the BOV when I want to increase the boost later on?

thanks for all your help guys

[boostboss]

There is a fantastic book called 'supercharged' by corky bell and it has heaps of useful formulae etc.

[bboy_10_lt]

Originally posted by djcontra
I would get 12psi of boost out of my charger, but I'm not sure if running a combination like that would be safe (for my engine, charger, and belt, stress-wise)

do you have a boost metter
I've got a custom charger on my car (you mean custom set up)
A V-9 supercharger can handle MAX 20psi and 65,000 RPM
the belt will be fine
and did you do anything to the engine like lowering compression

my TI is pushing 15psi
the motors been ported so it can handle all that power

[paul e]

>>Yeah I read that too, 6" crank + 3.33" s/c is what I was reading on this forum in past threads<<

Thats what IM running, and im making 11 psi.

[@bgynite@]

if your worried about to much boost and dont want to lower compression just get a water alky injection system from aquamist or aquastealth.

it cools intake air and prevents detonation. it makes your car safe to run up to 12psi with out having to lower compression.

well thats my 2 cents