How can/Could a BOV give you more BHP?

[Blackie]

Is it possible that a dumpvalve could add BHP? I thought they were to let off excess pressure to stop the turbo stalling?

[Bailey.]

think youve answered your question mate, may be wrong, but dont think they make anymore power, just puts a longer life on turbo's.

[Blackie]

I have seen one advertised that claims it adds 20 brake, didn't think it sounded right

[nevins]

This is my next investment, as I'm running the pigeon mod on the 14a right now.

[Abz]

This is my next investment, as I'm running the pigeon mod on the 14a right now.

You are attaching a pigeon to your car Nevin

 

Blackie as far as I am aware you can't gain power from it, like you mentioned in your first post.

[nevins]

Attaching the fuckers there already, its a pointless mod which I hate having on the car.

[a98pmalcolm]

Isnt that when u just block off were the BOV was to get super flutter?

[nevins]

Yes, you basically remove the recirc and block off everything so the only place for the pressure to go is back through the turbo, I hate it.

[Homer]

It's impossible them to provide any more BHP, their only purpose is to reduce noise when changing gaer (though if it's externally vented it negates the noise suppression)

 

think youve answered your question mate, may be wrong, but dont think they make anymore power, just puts a longer life on turbo's.

 

A common myth

[Swampy442]

The only way you could gain power with a Bov is if the existing one was leaking pressure.

[stevie_b]

I thought [dumpvalves] are to let off excess pressure to stop the turbo stalling?

 

A common myth

 

I didn't know that. I thought Blackie was spot on there. Every day's a school day.

[marbleapple]

I didn't know that. I thought Blackie was spot on there. Every day's a school day.

 

I hadn't thought about it until now, but how does a turbo stall since isn't it effectively a propellar? (Am I showing my ignorance?)

[dude]

It can spin at up to 100,000 rpm it can in theory hit a wall of air and hence stall !!! Bit like water becomes very hard when you hit it at a certain speed or faster;)

[davej705]

It can spin at up to 100,000 rpm it can in theory hit a wall of air and hence stall !!! Bit like water becomes very hard when you hit it at a certain speed or faster;)

 

OT I know but is it true a turbos blades can go supersonic if not wastegated? Where they spin so fast?

[marbleapple]

It can spin at up to 100,000 rpm it can in theory hit a wall of air and hence stall !!! Bit like water becomes very hard when you hit it at a certain speed or faster;)

 

I understand. Thanks.

 

On the basis of the above it's no wonder the fins on the turbos often disintegrate then. There would be a lot of force on them if they hit a wall at 100,000 rpm

[p3te]

Haha youve seen that in my ad:-D its a ancient bov and i was joking about it sayin it was brand spanking new and adds 20bhp lol.

[Swampy442]

A turbo compressor is basically the compressor part of a jet engine, with no dump valve you get stall followed by surge, thats the noise you hear with no bov.

[David Reid]

It will only make more power if the standard one leaks. As mentioned the main reasons are to prevent stall improving responce and increasing turbo life.

[Kirk]

BOV's do NOT prolong turbo life nor do they give you extra BHP. This subject has been done to death already

[stevie_b]

I hadn't thought about it until now, but how does a turbo stall since isn't it effectively a propellar? (Am I showing my ignorance?)

 

This is probably paraphrasing what others have written, but the way I think about it is that the intake side of the turbo is pushing lots of air into the intake manifold. That air will be being squeezed in at much higher pressure than atmospheric pressure. When you stop driving the intake turbine blades (i.e. when you drastically reduce exhaust gases by engaging the clutch), all that air is going to want to escape...fast! Due to the shape of the turbine blades, air escaping back out the way it came will try to turn the blades the other way. Hence, the turbine could stall or even reverse if enough air does this. A BOV provides a safe escape for the built-up pressure. Kind of like a fire exit in a very overcrowded building.

[Scott]

Only thing it might help slightly with is a little less spool time when changing gear. As the gas is vented out, rather than hitting the turbo on its way back, it won't slow the compressor down as much. Re-circulating one would do a better job though as it is quieter and the excess boost goes back in pre-turbo helping it spin also.

 

You MIGHT see a BHP increase if you threw it really really really fast and hard behind you as you were moving forward. The same would go for any object though.

[Swampy442]

This is probably paraphrasing what others have written, but the way I think about it is that the intake side of the turbo is pushing lots of air into the intake manifold. That air will be being squeezed in at much higher pressure than atmospheric pressure. When you stop driving the intake turbine blades (i.e. when you drastically reduce exhaust gases by engaging the clutch), all that air is going to want to escape...fast! Due to the shape of the turbine blades, air escaping back out the way it came will try to turn the blades the other way. Hence, the turbine could stall or even reverse if enough air does this. A BOV provides a safe escape for the built-up pressure. Kind of like a fire exit in a very overcrowded building.

 

 

Pretty much that, except the turbo is always being driven by the exhaust gasses, and the problems come when you close the throttle butterfly, its effectively blocking the intake off leaving it full of pressure with nowhere to go except back through the turbo. A bov/recirc valve is a way to release that pressure

[dandan]

There's an aurgument to say that a vented to atmo BOV will gain you hp over a recirculating version due to intake heating (hot, previously compressed air being fed back into the compressor inlet to be heated once again every time you close the throttle and dump air).

 

I wouldn't like to try to quantify that though

[jagman]

I hadn't thought about it until now, but how does a turbo stall since isn't it effectively a propellar? (Am I showing my ignorance?)

 

 

It's to do with velocity of the air , if an aerofoil shape has no or slow speed of air over it then it "stalls" - think aircraft trying to fly too slow .

When the compressor produces boost pressure , but the air has low/no flow (throttle) is closed , then the compressor stalls .

 

It's velocity ....

Pressure,flow,velocity , and turbulence are all linked

[David Reid]

BOV's do NOT prolong turbo life nor do they give you extra BHP. This subject has been done to death already

 

They do compared to not runinng one, the only reason no one sees failure assosiated with not running is no one does sufficient mileage.

 

I even dont intend on using one