BLACK10
Full Access Member
On the paxton S/C's is air supposed to flow from the bypass until it reaches a certain RPM then close ?
question
- Thread starter BLACK10
- Start date
BLACK10
Full Access Member
???? any help?
I DON'T have a Paxton, but have had other blowers on other vehicles, and those bypass vavles were always Vacuum Operated. RPM's weren't really what opened and closed them.
With my Gen2 L (supercharged), my '93 Cobra (supercharged), and my '91 GMC Syclone (turbocharged), I could run the RPM's to redline if I wanted, with light throttle, and never get any boost.
Throttle position determined when the bypass valve opened and closed. To me, this is the better way to operate a bypass valve.
With my Gen2 L (supercharged), my '93 Cobra (supercharged), and my '91 GMC Syclone (turbocharged), I could run the RPM's to redline if I wanted, with light throttle, and never get any boost.
Throttle position determined when the bypass valve opened and closed. To me, this is the better way to operate a bypass valve.
Stingray
Full Access Member
I'm not sure what the Paxton setup uses - a bypass valve recirculates the air(boost) back into the blower. That's used with engines with mass air flow sensors. A blowoff valve just vents the air to the atmosphere (I think this what the Paxton uses???) Either way, are you asking if air is either pulled into of flowing out of the valve when the engine is not in boost? The only time the valve should be open is if you are over boosting or you closed the throttle plates after being in boost.
RedSrt007
Active Member
If your asking about the bypass (as in blow-off valve), It does not run off rpm, it is ran off boost psi. When it reaches a certain level of pounds, it blows off the rest into the atmosphere similar to a turbo blow-off. Its not a ricer psst loud, its more of a whooosshhhh sound.
-Red
-Red
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Stingray said:
Actually, a Bypass valve does just what it's name says it does - it allows air to Bypass the supercharger and go straight into the engine. Basically it allows for cooler intake temps.
When you put your foot down on the gas, the bypass valve closes and directs all of the air into the supercharger.
I have yet to see a Turbocharged vehicle with a Bypass valve. Generally, all of the intake air is routed through the turbo before it goes into the engine. During normal driving, the turbo isn't spinning fast enough to create boost, so it doesn't heat the intake temp up very much.
Always remember - Charged (boosted) air = HOT air. When you compress it, it heats up. Which is why Intercoolers were developed.
A Blowoff valve is a different animal all together.
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And I *think* what you're referring to with the 'whooosshhhh' sound is a blow-off valve, but it does NOT control boost. The 'whooosshhhh' sound happens when the throttle plates are suddenly closed (you take you foot OFF the gas pedal). What is happening is the blowoff valve is releasing the Charged (boosted) air into the atmosphere that is stuck between the supercharger/turbocharger and the throttle body. Otherwise, when the throttle plates close, all of that charged air has nowhere to go, except back into the blower - which can be tough on it (especially a turbo).RedSrt007 said:
To control boost (on most street applications), a supercharger uses a simple pulley which is designed for a maximum boost level. To increase that boost level you use a smaller pulley - which in turn drives the S/C faster. To decrease boost you use a larger pulley which drives the S/C slower - simple enough.
To control boost on a turbocharged vehicle, a Wastegate is used to control turbocharger RPM's (which is what determines your boost level) - it's simply a spring-loaded exhaust gate which is operated with engine vacuum/boost. When the pre-set boost level is reached, the wastegate can open a little, or a lot, and can constantly be manipulated by engine vacuum to control boost. It allows some of the exhaust gasses to bypass the turbocharger, which in turn limits the boost level.
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ViperRamRacing
New Member
Bypass valves on superchargers divert the air from the output side of the supercharger to the inlet side of the supercharger. In a loop. If this did not happen the throttle blades might not close due to the pressure on them and the engine would not shut down and go back to idle. If the pressurized air at the supercharger outlet were induced into the engine during deceleration the engine would go into an over run condition. This would cause an extreme lean condition as the computer looks at the TPS (throttle position sensor) that is closed and cuts the fuel. The mass air flow sensor is upstream from the supercharger inlet does not have much involvement in the AFR (air fuel mixture) at idle (when the computer sees the TPS closed) and is primarily a function of engine speed, engine temp, vehicle speed. and throttle position.
Stingray
Full Access Member
Hamrhead - this is what I was referring with the bypass valve. The Paxton is not 'bypassed' before the air enters the engine. The only direction the air flows through the bypass is back to the front of the blower. All the air that enters the engine will come through the blower both in boost and idle.ViperRamRacing said:
OK - I see. I've never ran a Centrifugal Supercharger. They are definitely different than the Roots style. On my '99L and my '93 Cobra, which both had Roots type blowers, the Mass Air Sensor is Before the blower.
With my '93 Cobra, I purchased a BBK Instacharger kit for it, which was an Eaton Roots blower. You could see right up into the thing how the bypass 'door' worked. It diverted intake air around the blower and into the the engine, until you stomped on it. At that point, the vacuum operated 'door' would divert all incoming air into the blower. I never took my '99L apart, but I can only assume it worked the same way.
With my '93 Cobra, I purchased a BBK Instacharger kit for it, which was an Eaton Roots blower. You could see right up into the thing how the bypass 'door' worked. It diverted intake air around the blower and into the the engine, until you stomped on it. At that point, the vacuum operated 'door' would divert all incoming air into the blower. I never took my '99L apart, but I can only assume it worked the same way.
RedSrt007
Active Member
Man...damn good info! thanks...I learned something new..
AWDisuzu
Full Access Member
wow there are so many incorrect answers here it's amazing.
Stingray
Full Access Member
Well since you have all the right answers post em and help us all out. Smart ass comments just don't seem to help too much :dontknow:AWDisuzu said:
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