Matt, I really don't want to argue with you, but honestly I 'feel' you're the one missing the point. You seem to have a 'turbo' mentality stuck in your head.

If I suddenly let off the throttle, the engine rpms drop, the supercharger pulley rpms drop, boost drops, and there is NOTHING TO BLEED. It's all tied together... immediate feedback. You're thinking 'turbos' and 'turbo lag'. In a turbo setup, yeah, if I let off the throttle the exhaust is still spinning the turbine and making boost, so yes I need to bleed it. Such is simply not the case with a SC setup.

Trust me, SC kits never had blowoff valves until the turbo crowd made them 'trendy'. Domestic SC kits Paxton, Procharger, whatever, have been running just fine without BOV's for years.

 

Thats cool. But I must say I have built a 454 chevy with a B&M blower at school of course without a blow off valve. I have installed a Paxton Supercharger for a Mustang Notch back bored 30 over and stroked without a Blow Off Valve. BUT I DID Install a Vortech supercharger on a 91 Trans Am 350 with a Blow Off Valve 6 years ago. The difference between them all was the Trans am was more than 4 pounds. And I thought it was because theres more pressure that called for the BOV on the vortech.

 

Well, I'm sure someone will come along and clear up all this for us (or me, heh). Just checked Paxton's site, and their current models use a 'compressor bypass valve'. Which, I'm assuming is similar to Jackson Racing's setup (ie. pressurized air is returned to the SC inlet for reuse).

 

Jackson Racing uses a Roots type blower. Vortech uses a Centrifugal system. JRSC's don't come with a BOV of any sort. Vortech systems do.

I would suggest reading up on these 2 different types of supercharger systems.

Shingo

 

ok ok this may be old by now , but I STARTED IT! both of you stiffle......you need a blow off valve. when pressure is high and you slam the door it will pressurize the 'container' of your plumbing - in both turbo and SC cases the air will just bounce around back and forth between the throttle and blower - not allowing any additional to enter the blower - cavitation. luckily we're talking about air so i don't believe any damage could come of this. every SC company provides a way to bleed excess air. your example of a 25 lb pulley with a 9 lb blow off is correct - it will blow at 9 and waste the other 16 , but before it blew you had tons more 'potential' boost however that may be offset by the added drag of that tiny little pulley trying to push that much air.