vortec supercharger boost problems

2000gt2beat · 06-23-2009

I just recently installed a vortec supercharger on my 83 gt and after the dyno this weekend found out it was only boosting 2.5 psi @6100rpm. When i talked to vortec they told me with my combination i would have some problems making the full 6 psi and told me i needed an 8 inch crack pulley which they offer but only in an 8 rib belt, they also offer the blower pulley but changing the stock one will void the factory warrenty whick i want to avoid. Anyone have an idea where i could find a 6 rib 8 inch pulley for my 5.0?

mell0 · 06-23-2009

i would check out your bypass or blow off valve (check the vacuum line running to the intake) and check the whole system for boost leaks. also on your boost pressure gauge (if it's mechanical) make sure there are no kinks in the vacuum line running to your gauge itself.

Txnavyman10 · 06-23-2009

i may be wrong about the crank pulley but i'm sure you don't change crank pullies to produce boost you change the supercharger pulley. Smaller the pulley faster is spins producing more boost. Pullies are the first thing to change when wanting more boost. Powerpipes, and piping are another way to produce more boost. I would think maybe belt slippage but you aren't producing enough boost for that. Did you buy the vortech used?

2000gt2beat · 06-24-2009

No it was a new system from vortec. They offer a smaller blower pulley but it will void the manufacturer warrenty. Thats when they suggested putting a larger crank pulley which they had but it is an 8 rib and i needed a 6 rib.

2000gt2beat · 06-24-2009

I went over the piping while on the dyno and found no leaks. Since it is only supposed to make 5-6 psi i didn't use an intercooler or a blow off valve they said it would be safe. Does the piping size from blower to carburator have any affect on the boost produced?

Txnavyman10 · 06-24-2009

well about the piping and about not leaking it might be hard to tell at low boost 700rpms versus high boost around 5500 rpms you know what i mean. I know vortechs are a highly recommended sc and are on the rise too. If vortech said that it will produce 5 to 6 lbs on that pulley and your motor and it isn't then its false advertisement so they need to warranty a pulley that produces 5 to 6 lbs. Theres a lot of hp between 2.5lbs versus 6lbs. Have you talked to the installer?

2000gt2beat · 06-25-2009

Yeah i did and spoke with vortec as well they told me with the combination i had probably flows to well to let the s/c build boost. They said it was designed around a stock flowing 5.0. I think i am going to go ahead with the blower pulley. I appreciate the help.

mell0 · 06-28-2009

wait you dont have any type of bypass valve? and i saw you mentioned carburetor, what kind of engine is this in?