so i' was just thinking tonight. i have underdriver pulley's on my crank (which is quite a bit smaller) and on the water pump (which is quite a bit bigger) than stock. could that be why i'm only making 2-3 psi when i should be making 8 (have a 96 gt)?? so if that's true i would need to get a smaller supercharger pulley to make up for it?? if that's the case then what size pulley would i need? knowing that a smaller crank pulley will turn less rpm's, i thought this could be the problem. correct me if i'm wrong.

 

im surprised the vortech manual didnt say anything about underdrive pulleys. yes you need to go back to stock if you want to make 8 pounds. Call vortech about what size belt you need.

 

underdrive pulleys spin the blower slower, just get the stock pulleys back on there to make some boost.

 

under drive pulleys arent worth more then a couple hp. just take them off, dont run a smaller sc pulley to make up for it

 

Your big problem is the crank pulley. Switch just that one back to stock and you'll be fine. It is possible that your crank pulley is 'piggybacked' on the stock one now. Either way, get the belt on the stock sized one, and you'll be fine.

 

wow i feel like a idiot. boosting just fine now, thanks for the help.

 

Man I sure am glad that I read your post because I am about to get my car back with a fully foged motor and 12lb pulley and i would have been disappointed if i were only making 7lbs of boost and didnt know it. thanks

 

glad to hear its working for you now