I have a 6# Powerdyne supercharger on my 95 Z28, it's only making about 5#. Is it possible to upgrade the pulley to make a little more boost without hurting anything? If so where can I get a pulley? Or how can I make more boost without the pulley upgrade? Thanks.

 

You may have a very efficient air path and the air volume flowed through the SC shows as 5 lbs. of boost. Or you could be having some belt slip at higher RPM under load. A pulley change (recommend a crank pulley in a larger diameter) could raise your boost level but you will be very close to over-speeding the impellor in the SC and also the internal belt for the Powerdyne. This could result in a broken belt or even impellor failure. You didn't mention if you have a 6 speed or automatic but, with a 6 speed I wouldn't recommend switching pullies as people with manual trannies tend to rev their engines higher and may have a higher risk of damage to the internal belt or impellor due to this higher RPM (above say 6000). Folks with automatics seldom rev past 6000 RPM and therefore stay within the "safe" speeds for the Powerdyne head unit.

Having said all that , I run the 2.70" (Ford 9 lb. pulley) pulley modified for an F-body by Powerdyne on my T/A. Mine is an automatic and set up to shift at 5600 RPM. I see a little over 6 lbs. on the boost gauge when I sneak a look (not often). Safe max impellor speed for the Powerdyne BD-11 head unit is 43K RPM. The standard Powerdyne 6 lb. crank pulley coupled with the 2.70 SC pulley puts the impellor at about 42K RPM at 6000 RPM. Stretch that engine RPM up to say 6400 (or miss a shift) often and I would expect to at least break an internal belt (just ask the Mustang 9 lb. boost folks at corral.net) and at worst damage the impellor and shoot pieces down through the intake and possibly the motor.

It's your call but I'd check the belt tension for slip first. Another 1 lb. of boost is maybe 15 RWHP and might not be worth the chance of damage.

later ... Larry S.