What pulley size do I need for 8psi out of my whipple?

It's a single belt setup on a 2003 5.3.

Thanks

 

mine is a 3" and it gives me 5psi. Mine is the Bigblock and I am not sure if the crank pulley's are the same size as the small blocks. You can always call whipple and ask them. Every 1/8" smaller gives you 1 psi i think. So if they are the same, you would need a 2-5/8" pulley for 8psi.

 

I have a 3.75" one on my single pulley setup and I get 11-12 PSI at WOT. Some of that may be backpressure from the Flowmaster cat-back, but a 4" pulley netted me 8-9 PSI, so the 1/8" = 1 lb equation seems to hold true.

 

That's what I tried to do this morning, but the guy kept asking me to hook it up to a boost gauge to find out what it makes now before he could recommend another pulley. I finally gave up after telling him THREE times that it was still in the box and the gauge wouldn't do much to help me out.

Can anyone else confirm the 4" pulley for 8psi?

 

call and ask for either Chris in sales or Jeff in tech support. One of those should be able to help out.

 

Thanks Linda. Jeff confirmed that the 4" should put me at about 9psi.