What is that sound from a EVO?
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Launching!
Joined: Feb 2005
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From: Central California
What is that sound from a EVO? Was at a little league game today my vette was park on the curb and 2 EVO's at different times drive by and I heard a loud noise like a release valve anyone know what it was?
Every time the throttle body closes the blow off valve will let any rise in pressure "blow-off" into the atmosphere instead of going back and smacking the turbine wheel. That happens every time the throttle body closes.
Aftermarket companies sell valves that make the "pssffft" more noticable. You probably heard the Evo boys with aftermarket valves.
Aftermarket companies sell valves that make the "pssffft" more noticable. You probably heard the Evo boys with aftermarket valves.
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Teching In
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I wouldn't be so sure. Did it sound like they were running like crap or did they stall anywhere near by?
Evo's run very poorly unless they use a recirculating blowoff valve and those don't make a whole lot of noise. They run poorly because the blowoff valve is after the MAF so the air has already been counted by the ECU, so when you vent that air into the atmosphere instead of putting it back into the intake path the car runs extremely rich since there is less air than what the ECU expected to be there. Cars like the SRT-4 use a vent to atmosphere blowoff valve and those are the ones you can really hear every time they shift or let off the gas.
There are bandaids that will let you use the VTA setup but it provides no gains so it's typically considered a "ricer" mod.
Evo's run very poorly unless they use a recirculating blowoff valve and those don't make a whole lot of noise. They run poorly because the blowoff valve is after the MAF so the air has already been counted by the ECU, so when you vent that air into the atmosphere instead of putting it back into the intake path the car runs extremely rich since there is less air than what the ECU expected to be there. Cars like the SRT-4 use a vent to atmosphere blowoff valve and those are the ones you can really hear every time they shift or let off the gas.
There are bandaids that will let you use the VTA setup but it provides no gains so it's typically considered a "ricer" mod.
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Originally Posted by cletus323
I wouldn't be so sure. Did it sound like they were running like crap or did they stall anywhere near by?
Evo's run very poorly unless they use a recirculating blowoff valve and those don't make a whole lot of noise. They run poorly because the blowoff valve is after the MAF so the air has already been counted by the ECU, so when you vent that air into the atmosphere instead of putting it back into the intake path the car runs extremely rich since there is less air than what the ECU expected to be there. Cars like the SRT-4 use a vent to atmosphere blowoff valve and those are the ones you can really hear every time they shift or let off the gas.
There are bandaids that will let you use the VTA setup but it provides no gains so it's typically considered a "ricer" mod.
Evo's run very poorly unless they use a recirculating blowoff valve and those don't make a whole lot of noise. They run poorly because the blowoff valve is after the MAF so the air has already been counted by the ECU, so when you vent that air into the atmosphere instead of putting it back into the intake path the car runs extremely rich since there is less air than what the ECU expected to be there. Cars like the SRT-4 use a vent to atmosphere blowoff valve and those are the ones you can really hear every time they shift or let off the gas.
There are bandaids that will let you use the VTA setup but it provides no gains so it's typically considered a "ricer" mod.
Well, the bypass or diverter valves which reroutes excess charge air back into the intake can be pretty loud. It sounds more like a "whoosh". A blow-off valve, which by definition, dumps air into the atmosphere is designed to have more of a whistling, squealy sound to it and therfore sounds more like a dying bird.
