Supercharger BOV idle setting
#1
Thread Starter
Supercharger BOV idle setting
Is a blow off valve suppose to expel air when the car is just idling? Asking because I just bought a BOV and wondering how tight to adjust the spring.
#3
Thread Starter
I have a Go Fast Bits Stealth FX and a non-aftercooled Comptech SC running the stock pulley.
I noticed that the plastic stock Bosch diverter valve used to have a good amount of air coming thought it when the car was idling, wondering if I should set the BOV spring soft enough to allow some air out too.
The SC is always pumping air while the car is running, so where is all this air going when the throttle body is closed?
I noticed that the plastic stock Bosch diverter valve used to have a good amount of air coming thought it when the car was idling, wondering if I should set the BOV spring soft enough to allow some air out too.
The SC is always pumping air while the car is running, so where is all this air going when the throttle body is closed?
#4
The air is supposed to be released when you are at idle or cruise. The way the bosch valve works is that whenever you have a slight vacuum in the intake plenum (because the throttle is not fully open) this actuates the diaphram and releases the excess boost. When you open the throttle the boost comes on and the diaphram is closed.
#5
Originally Posted by AusS2000,Aug 16 2004, 05:28 PM
The air is supposed to be released when you are at idle or cruise. The way the bosch valve works is that whenever you have high vacuum in the intake plenum (because the throttle is fully closed) this actuates the diaphram and releases the excess boost. When you open the throttle the boost comes on (i.e. no vacuum) and the diaphram is closed.
#6
Originally Posted by stphotographer,Aug 16 2004, 09:05 AM
Does your blow off valve expel air when the car is just idling? Asking because I just bought a BOV and wondering how tight to adjust the spring.
#7
Ehh?
When your engine is at partial throttle the engine is trying to suck more air than the throttle (hence name) will let it. As a result the pressure in the intake manifold (between the throttle body and the head) is low (I guess 'high vacuum' is an ass backwards way of saying it). But if you're still revving (by this I mean the engine is still turning) then the SC is still pumping but the air has nowhere to go. The Bosch bypass valve is triggered by the line from the intake manifold (or more correctly by atmospheric pressure from the return line).
Note the difference between the Bosch set up and a blow off valve. In the Comptech install it specifically states that the Bosch valve should point down rather than sideways. This way, boost pressure is pushing on the side of the valve rather than against the diaphram and spring. So it's not a BOV at all, but a vacuum actuated bypass. A BOV uses intake manifold pressure directly against the diaphram vs an adjustable spring + boost feed. The spring is adjustable as is control of the boost feed pressure when a boost controller is used.
When your engine is at partial throttle the engine is trying to suck more air than the throttle (hence name) will let it. As a result the pressure in the intake manifold (between the throttle body and the head) is low (I guess 'high vacuum' is an ass backwards way of saying it). But if you're still revving (by this I mean the engine is still turning) then the SC is still pumping but the air has nowhere to go. The Bosch bypass valve is triggered by the line from the intake manifold (or more correctly by atmospheric pressure from the return line).
Note the difference between the Bosch set up and a blow off valve. In the Comptech install it specifically states that the Bosch valve should point down rather than sideways. This way, boost pressure is pushing on the side of the valve rather than against the diaphram and spring. So it's not a BOV at all, but a vacuum actuated bypass. A BOV uses intake manifold pressure directly against the diaphram vs an adjustable spring + boost feed. The spring is adjustable as is control of the boost feed pressure when a boost controller is used.
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#10
Originally Posted by AusS2000,Aug 16 2004, 07:29 PM
Ehh?
But if you're still revving (by this I mean the engine is still turning) then the SC is still pumping but the air has nowhere to go.
But if you're still revving (by this I mean the engine is still turning) then the SC is still pumping but the air has nowhere to go.
At 1000 rpm idle speed the centrifical superchargers are not producing boost in the S2000.