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.

 

ok but when does it do it ? i assume whenever the car wants to shift. I just want more info on this whole topic. But its not really something i can google up. its more of feedback from car owners.

 

boost is constant with an auto tranny, so you dont hear the bov between shifts

 

wow. so no way to hear that turbo or anything like that 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.

 

wow. so no way to hear that turbo or anything like that and no sense in getting aftermarket BOV.

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.

 

when you let off the gas in an auto, it will "blow off"...the good thing about autos is that it keeps the turbo spooled. you dont have to spool it up everytime you rocket into another gear :lol:

 

boost is constant with an auto tranny, so you dont hear the bov between shifts

Boost isnt constant with an automatic, it will change when the transmissions shifts.

Really turbos are engine dependent, not transmission dependent, both auto and manual have the same mechanical systems with a turbo.

 

interesting to learn. The link doesn't work on my computer for some odd reason. my explorer doesn't want to open it up.

keep in the info coming guys.

I was only wondering about the sound because i started doing a little researching on turboing my camry. Just wondering about the sounds it could make because other then the whole speed and boost of the car , i want to hear it as well.

i figured that boost isn't constant, when your tranny shifts your car thats when left go off that gas thats when the car is shifting so yea thats where you hear the BOV. As for functions of the BOV, i dunno about that, i;ve only know that BOV makes that PSHHH sound. lol

 

when your tranny shifts your car thats when left go off that gas thats when the car is shifting so yea thats where you hear the BOV.

True for a car with a manual tranny. You normally let off the gas before you shift.

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.

As for functions of the BOV, i dunno about that, i;ve only know that BOV makes that PSHHH sound. lol

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.

 

ahh~! very good explaination 88LE. does that mean with an auto everytime you lay off the gas the BOV blows? well giving a certain speed in order to build up pressure.

Would the PSHH sound be comparable to a manual sound ? I figure it might not be always as good sounding. But a very nice sounding PSHH.

 

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.

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.

 

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.

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.

 

does that mean with an auto everytime you lay off the gas the BOV blows? well giving a certain speed in order to build up pressure.

Yes.

It'll blow off even if your not seeing any boost. It just won't be as loud.

The more pressure there is the louder it'll blow off.

Would the PSHH sound be comparable to a manual sound ? I figure it might not be always as good sounding. But a very nice sounding PSHH.

Its the same regardless of the type of tranny.

 

i dont think thats how it works.

Its not a matter how you think it is, its mechanics.

 

Is it possible for me to put a BOV on my 04' Camry auto?

 

well it is if you put on a turbo kit. but i doubt you can put on a BOV w/o a kit but you might somehow pull things off.

 

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.

 

Is it possible for me to put a BOV on my 04' Camry auto?

unless you put a turbo kit on your car there is no need for a bov. and if you put it on a stock NA car it wont work.

 

Its not a matter how you think it is, its mechanics.

I drove an automagic :lol: 1996 Toyota Twin Turbo Supra last weekend, and if I remeber correctly I could not hear the blow off valve sound during gear shifts untill I let off of the gas.

 

I drove an automagic :lol: 1996 Toyota Twin Turbo Supra last weekend, and if I remeber correctly I could not hear the blow off valve sound during gear shifts untill I let off of the gas.

thankyou very much for proving my point.

 

^^ Exactly.

Thats what I was trying to tell you fools. :lol:

As I said earlier, a bov is actuated by pressure alterations. IE: going from boost (positive manifold pressure) to vacuum.

 

well we were both on the same page.

 

great! now i understand as well so we are all on the same page.

 

^^ Exactly.

Thats what I was trying to tell you fools. :lol:

As I said earlier, a bov is actuated by pressure alterations. IE: going from boost (positive manifold pressure) to vacuum.

I was under the impression that Flashmn thought otherwise?