Yes automatics have blow off valves. All turbos have blow off valves of some sort. Most stock bov's dont go psssshtt.... but if you have an aftermarket one on an automatic car... it should still do it.
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wow. so no way to hear that turbo or anything like that 
and no sense in getting aftermarket BOV.
and no sense in getting aftermarket BOV.Letting off the gas is the same in both... There's an auto eclipse gsx around here pushing 300whp i think. BOV sounds awesome and you can hear it when it shifts...
Good thing about turbo autos is that you can torque brake them so you can build up boost before you launch.
Good thing about turbo autos is that you can torque brake them so you can build up boost before you launch.
bowlofturtle said:wow. so no way to hear that turbo or anything like that
A bov functions the same whether its on a car with a manual or auto tranny.
BOV is actuated by vacuum, so it'll only blow off when you let off the gas.
And a BOV does more then just give you a cool psshhh sound.
Heres a video of a turbo Mustang:
http://www.turbomustangs.com/car_images/featuresteve/867s_165incar.wmv
You can hear the turbos (high pitched whining sound). And also the BOV when he lets off the gas at the end.
True for a car with a manual tranny. You normally let off the gas before you shift.bowlofturtle said:
But in a car with a auto tranny you normally just floor it and don't let off the gas.
BOV is actuated by pressure alterations. Boost (positive manifold pressure) keeps the valve within the BOV closed, IOW you have pressure pushing on top of the valve keeping it closed.
When you let off the gas theres vacuum sucking on the valve. At the same time theres a lot of pressure build up on the other side of the valve. The valve opens up and releases this built up pressure (air) and thats where the cool pssshh sound comes from.
When you let off the gas theres a build up of pressure between the turbo and throttle body. The built up pressure is a result of the throttle body closing.
This built up pressure needs to go somewhere. Either released into the air (bov) or blown off then recirculated back into the intake (recirc. valve).
So it helps reduce / eliminate compresser surge which can damage the turbo. It also gives you that cool pssshhh sound.
Yes but engine RPM changes and when the engine RPM changes, the levels of boost change for a moment, SO the blow off valve would sound, as the engine would for a moment suck less air than the turbo is pushing in.
Only cars that you really dont use a blow off valve are diesels, but they lack throttleplates all together.
i dont think thats how it works. the reason is sounds on a stick is because when you shift you let off the gas thus closing the tb. that presure needs to leave so there is no damage to the turbo. in an autop the tb is always open at wot therefore not needing the bleed off any boost pressure during the shifts. the only time you should hear the bov is when you let off the gas in and auto.Flashmn said:Yes but engine RPM changes and when the engine RPM changes, the levels of boost change for a moment, SO the blow off valve would sound, as the engine would for a moment suck less air than the turbo is pushing in.
Only cars that you really dont use a blow off valve are diesels, but they lack throttleplates all together.
also its not a supercharger where you are rpm dependant. with a sc yes you lose boost because the rpms drop. a turbo charger, especially on an auto, will be able to hold the same amount of boost when the auto shifts.
Its not a matter how you think it is, its mechanics.
exactly, how it works. so its not gonna blow off boost if there is no reason to.Flashmn said:Its not a matter how you think it is, its mechanics.
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