Have I got a BAD one??

Ive got my sn92 installed and rotateing Clockwise ( looking from the pulleyside to the backside of the unit)OK, heres the question, these a small port on the top side of the unit, right above the outlet of the blower, I attached a gauge to this port and at Idle I have about 12 inchs vaccum, but at no point in RPM Does this port get boosted to anything in the positve pressure range. Now with that said, at about 4500 rpm I have 15inchs vaccum , and at 5200 rpm vaccum drops to 10 inches. This isnt BOOST is it??I think I should see a positive number here,am I wrong?? If Iam not wrong whats wrong? There are no noises, vibration, nothing that indicates that something is wrong....:(

two things. you should reference the amount of boost you are making from the intake after the throttle body.

second you won't see boost until you put a load on it. reving in neutral wont put a load on it. go to 3000 rpm in 3rd and then mash it. you'll see boost as you climb in rpms.

mike

Ok, that works, but now all I have is 2.5 psi boost with a 3 inch pulley at 5000 rpm. Ive got 8.5- 9 compression, is that to high? Or is the blower poor? Al

3" pulley your spinning the balls across the impeller shaft or your belt is slipping alot. If you have a 4" you will probably see 5-6psi and not cause the belt to slip.