Do all turbo-charged vehicles have a BOV?

[SleepingEclipse]

As the title states, do all turbo charged cars have a BOV? I know its kind of a newbie question, but someone was telling me that not all turbo's have bov(I'm talking cars, semi's, pickup trucks, etc, ANY turbo motor)...I thought they all had them, but some where just more 'pronounced' aka louder than others. Thanks guys.

 

[HSK]

adding to noobish questions (related to the main question):

i was just at a local import meet and saw a protege/mazda-turbo and i didnt see a bov, he was all stock cept intake cone. i asked the owner n he said he has a bypass valve.

 

[SlowSpyder]

not all cars came with a bov/bypass valve, also not all cars came with intercoolers

 

[Aaron91RS]

89TTA
Why would you want to let that precious boost escape

 

[97GS-TSpyder]

turbo disels dont

 

[92redman]

Conquests/Starions didn't have blowoff valves or bypass valves. I am sure there are other cars that didn't have them.

 

[Defiant]

My '84 Datsun 200SX Turbo has no BOV, although there is a pressure release device on the intake plenum to let backfiring out. I don't think it's ever opened. Also not intercooled. I doubt it put out 5 psi, still on a T-25, but on a specific exhaust housing.

 

[SleepingEclipse]

Alright thanks guys. I wasn't sure about all turbo's having them, I kinda figured it was a normal thing for all of them to have.

 

[out there]

i have a friend with a 1.8t golf, and his pressure releasing item is called the "diverter valve"

 

[HokieDSM]

It's all the same, Blowoff Valves, Diverter Valves, Compressor Bypass Valve (what ours is "technically" called) -etc. They are all different names for the same thing.

 

[Tallen]

Many many stock turbo cars do not have one....though if you are upgrading, its always a good idea. They are also known as Compressor Bypas Valves.

 

[leakyfaucet]

turbo disels dont

Actually most semis do.

 

[sonicnofadz]

I've seen a few weird domestic cars in my scrapyard with no BOV, can't really recall what the were. Maybe they were volvos even (not domestic), not sure. If the car is only running mild boost (i.e. 5-10 psi) there probably isn't a need to have a bov as the pressure from the turbo is really low anyways. Did you paint your interior blue?! Please don't rice out your n/a =)

 

[SpoolnTsi]

Actually most semis do.

Did you ever hear one???? Daaammmnnnn!!!! Kinda sounds like Ric Flair...................only 100 times louder

 

[thekellbeast]

Stop right there. No diesels ever had a BOV. EVER. Say it with me. EVER. Deisel's don't have throttles, so they have no need for BOV's. A BOV releases the pressurized air during shifts, so that it doesn't flow backwards and damage the compressor wheel. Deisel's don't have this problem, because when you let off the throttle when you shift them, all you do is cut back on fuel. That's it.

When you're hearing trucks and buses "blow off," that isn't the BOV. That's the air brakes. Sorry to tell you, but that's how it is.

Now, there ARE some cars that came turbocharged from the factory without BOV's. These would include GN's, and some foreign versions of Rx7's. (they did make factory turbo versions before the FD).

Also, back when F1 used turbo's, there were very few cars that used BOV's. Hell, there were entire race series-es that didn't use BOV's. Rally, open wheel, you name it. Some people will contend that BOV's aren't neccesary at all. Name one occasion on which a F1 car failed due to excessive compressor surge. And they were running HIGH boost levels.

It's all up to what you want to do, and how much of an inner ricer you have.

 

[Defiant]

Also, back when F1 used turbo's, there were very few cars that used BOV's. Hell, there were entire race series-es that didn't use BOV's. Rally, open wheel, you name it. Some people will contend that BOV's aren't neccesary at all. Name one occasion on which a F1 car failed due to excessive compressor surge. And they were running HIGH boost levels.

Yeh, but only for a few hours.

What about the Offys at Indy? I'd think they did even less throttle-cycling than F1 cars.

 

[SpoolnTsi]

When you're hearing trucks and buses "blow off," that isn't the BOV. That's the air brakes. Sorry to tell you, but that's how it is.

What i heard wasnt air brakes thats for damn sure

 

[leakyfaucet]

When you're hearing trucks and buses "blow off," that isn't the BOV. That's the air brakes. Sorry to tell you, but that's how it is.

So I guess it's common practice to use the brakes uphill huh?

 

[95itchypsy]

What i heard wasnt air brakes thats for damn sure

what you heard was commonly called the "jake brake" truckers term for what motocross calls compression release. they have a button on the gear shift and it operates a valve that essentaily releases the engines compression....no compression...no power.

 

[Mackzero]

I believe the Renaults had no bov either, just spooled up till they couldn't anymore I guess....

 

[SpoolnTsi]

what you heard was commonly called the "jake brake" truckers term for what motocross calls compression release. they have a button on the gear shift and it operates a valve that essentaily releases the engines compression....no compression...no power.

I dont know much bout semi's so im definately in a position to argue but i do know that what i heard was no air brake. I dont think it was a jake brake either cuz its illegal to use them in the city's here in PA but i could be wrong. If it was, i sure as hell never heard one that sounded like that before

 

[thekellbeast]

Look, it may have been a jake brake, it may have been an air brake, but it certainly was not a BOV. They simply don't put them on deisels.

 

[SpoolnTsi]

Look, it may have been a jake brake, it may have been an air brake, but it certainly was not a BOV. They simply don't put them on deisels.

Dude, no need to get defensive :thumbdown Jake brake, maybe. Definately not air brake. I know what they sound like and he was on the gas when it happend. I said im not in a position to argue. Let it go. If they dont have then they dont. I dont know i was just stating what i heard

 

[AdoreGSX]

compressed air being let out usually sounds about the same...

 

[Defiant]

Dude, no need to get defensive :thumbdown Jake brake, maybe. Definately not air brake. I know what they sound like and he was on the gas when it happend. I said im not in a position to argue. Let it go. If they dont have then they dont. I dont know i was just stating what i heard

Truck air system compressors run all the time. When the resevoir tank reaches its setpoint, the excess pressure is bled off. It come out through a huddling valve, which is like the valve in your toilet tank: notice how the toilet runs and runs and STOPS? The shape of the orifice holds the valve open at lower pressure than it takes to open it, so when it shuts off it's almost instant and without leaking. When used in a air system, it will hold the valve open to below the release point so that the valve doesn't flutter near the release point- it drops the pressure far enough below the "full" level that it gives the compressor some more space to fill up. Truck compressors run full-time because if you never shut it off, it won't fail to come back on.
You're not hearing a Jacobs (same company as the drill chucks, originally) Engine Brake. You're not hearing a BOV. It's just the air system (brakes, horn, sometimes shifter) getting "full" and making room for more air.