I have just got my self a cheap ebay Blow Off Valve and i already have mounting just after my inter cooler to mount this lil sucker

 

what i would like to know is where do i run the vac line to???

 

Its going on to a 4agze supercharged running 8 psi

Edited October 14, 200817 yr by AE80Rollaguy

inlet manifold.

The bov really wont do anything unless the supercharger is hooked up continuously and even then it wont be alot, The supercharger switches off when you let your foot off so it wont be making boost and the supercharger is after the throttle body .

its a fail, i had a bov in my cooler piping when i got my 4agze, it would just open up when you get to high revs and do nothing when changing gears.

Arr yea thats what i thought all along... i thought it might have been worth a shot!!!

 

Haha any one Interestd in a brad new BOV :P

Edited October 14, 200817 yr by AE80Rollaguy

Dang I have just done the same the thing got my BOV fitted and I got nothing :D

Aynone got any clues on how I could make it work or just turbo convert the ZE?

i was talking to a guy on ebay who did make it work. but he said for the effort that he went to it wasnt worth it!

If its a standard gze, like trev said the entire intake system is under vacuum because the TB is before the charger, you could always fit one after then you would need a BOV. It would also increase throttle response (TB after charger)

Edited February 21, 200917 yr by Jason

Blow off valves, are there to vent excess air that a turbo is currently pumping to reduce the amount of pressure flow back that happens between the turbo and the throttle body when the throttle body closes. The vent of air allows the turbo to free spin happily and give you a boost in power between the gears, as the turbo doesn't stall and slow down.

 

With a supercharger the pump runs off the engine, possibly the the ecu may disengage the clutch of the charger between gears, which makes for some gains using a blow off valve. But any supercharger without a clutch; vortech and most whipple charges, a blow off valve will be ineffective and probably mean more lag between gears. That said, there is always the point where the throttle body caves in under huge pressure as throttle closes between gears at high rpm in big horsepower supercharged cars.

 

A blow off valve uses a piston with intake manifold pressure on one side, and constant turbo pressure on the other. With even pressure the piston won't move because there is a spring that maintains a default closed position, but as the the throttle shuts vacuum state begins in the intake manifold and the piston gets forced under the boost, and sucked under the vacuum to slide in its bore and open the valve. With a GZE throttle location this just doesn't happen.