BOV before or after IC

[Justin DuBois]

I think this topic might just start an argument - so here we go.

We all know that you need to recirculate vented air from the BOV when running with MAF, and that is to prevent a rich condition venting to atmosphere.

We also know running Speed Density allows for venting to atmosphere without affecting the AFR.

Here’s a side note: A well designed recirculation tube can help keep the turbo spinning.

Now - let’s hold that thought and consider what air to vent.

Would you vent air from before, or after the intercooler? and why.

 

[jdxnc]

Personally I don't think it matters, I've seen them ON the intercooler. It's more a matter of where it fits best for you.

 

[chrysler kid]

I mean you know how a blow off valve works. However:

My question would be; why can’t a blow off valve also function as a wastegate and bleed off pressure without changing the back pressure on a turbo charger

 

[Justin DuBois]

Personally I don't think it matters, I've seen them ON the intercooler. It's more a matter of where it fits best for you.

There is a school of thought that would say it is better to vent hot charge air before it goes through the IC to help reduce heat soak. This makes sense to me except... that recirculation config. I would rather vent cooler vs hot air back into if recirculating air.

 

[jdxnc]

I mean you know how a blow off valve works. However:

My question would be; why can’t a blow off valve also function as a wastegate and bleed off pressure without changing the back pressure on a turbo charger

Similar idea, using wastegates on the cold side to control boost.

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[pauleyman]

Similar idea, using wastegates on the cold side to control boost.

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Im not seeing what you're seeing Jason. Looks like traditional hot side gates and cold side BOV.

I have seen a valve on the cold side but not to control boost but to limit it in an emergency. Called a "popoff" valve. I want to say HKS used to sell one. Designed to blow open at a specific level to prevent motor failure. At least that's what I remember.

 

[llxkevinxll]

Cold side boost control has grown in popularity at least in drag racing on the big power stuff. Seems to be useful on the line to maintain turbo speed without building too much boost and over powering the grip of the track/tire.

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[jdxnc]

Im not seeing what you're seeing Jason. Looks like traditional hot side gates and cold side BOV.

I have seen a valve on the cold side but not to control boost but to limit it in an emergency. Called a "popoff" valve. I want to say HKS used to sell one. Designed to blow open at a specific level to prevent motor failure. At least that's what I remember.

There's an inline wastegate coming off the bottom of the throttle inlet. This is a local shop car to me, the second quickest coyote in the world.

"Conventionaly we see hot side wastegates for boost control. We also see some with only cold side control but how about both?
By combining traditional gates with cold side control we are able to use the benefits of each method.
We worked out a strategy to use one or the other or a combination of both to control boost by targeting a backpressure ratio going down the track. This enabled us to have complete control of the boost ramp on the two-step and launch all while being able to eliminate excessive back pressure (free horsepower) at higher RPM."

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[pauleyman]

There's an inline wastegate coming off the bottom of the throttle inlet. This is a local shop car to me, the second quickest coyote in the world.

"Conventionaly we see hot side wastegates for boost control. We also see some with only cold side control but how about both?
By combining traditional gates with cold side control we are able to use the benefits of each method.
We worked out a strategy to use one or the other or a combination of both to control boost by targeting a backpressure ratio going down the track. This enabled us to have complete control of the boost ramp on the two-step and launch all while being able to eliminate excessive back pressure (free horsepower) at higher RPM."

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Very interesting. I wasn't looking there.

 

[Justin DuBois]

Boyle's law says hot gasses - decreasing in pressure also decrease in temperature.

What I could use are a couple IAT CANBUS sensors plumbed into RaceCapture - and start doing some practical engineering.

 

[Vertoussolutions]

Personally I don't think it matters, I've seen them ON the intercooler. It's more a matter of where it fits best for you.

Facts

 

[beendenied]

I'm on Team No Blow-off-Valve-At-All

 

[diambo4life]

On my Mustang, it's on the lower intercooler pipe...not too far from the turbo outlet. Works just fine. My MAF is after the BOV though. I have always heard the closer it is to the throttle blade, the better...regardless.