Anyone running a blow off valve, step on in...

[Boostian]

Yea the recirculating aspect I don't get either. Like Evil said, with the amount of intake piping I have I would think that air under 25psi that suddenly has no place to go (when the throttle is closed) and is vented back into the intake pipe would just make its way back out of the air filter and potentially dump a bunch of pressurized air behind the MAF.

 

[Boostian]

Bob thank you for that info. The main reason I hooked mine up (like I said, it was included in a package I purchased) was for the "drop throttle flutter" to hopefully prolong the life of my turbo.

Again, my issue now is that I can't seem to get all the air to vent out. I get an initial expelling when I close the throttle but then still get compressor flutter in conjunction with (what sounds like) BOV flutter

And for the life of me I can't find anywhere that states the Turbonetics Raptor "Godzilla" BOV has different springs.

Also as far as I can see there is only one vacuum port.

 

[TurboBob]

with mine it takes away most of the drop throttle surge. I stull get some flutter after the pssht...

this should be the second port.

 

[BuickMike]

Not to hijack this thread, but what is the general consensus on eliminating part throttle surge then? Bigger turbo? electronic boost control?

To add some value here, recirculating the BOV (actually called a BPV or bypass valve at that point) does work as it keeps the metered air still in the system. This is how many turbo cars with MAFs are plumbed from the factory. WRX, STi, Volvo, etc. My guess is that the air blown out of the valve is still not enough to overcome the vacuum between the MAF and the turbo, so it gets sucked back in.

 

[TurboBob]

there are a few strategies for eliminating part throttle surge, depending on the combination and how bad the surge is.

Bob

 

[Boostian]

Bob:

I just realized that there is a hole in that second port. Thought it was just blocked off.

That being said, is there an issue that I have that open right now? And you said if I add a boost source to that it may help. I obviously need to get a fitting for it. Where can I tap that source from?

 

[vader87]

Without getting into the debate as well, BOV were designed for standard shift cars. It helps keep the turbo spinning while shifting gears. So when you release the throttle and it closes, pressure is released so that the pressure does not try to go back through the turbo, slowing it down. My Gensis has one and it was originally designed to recirculate the pressure back into the intake pipe. I have replaced it with one that vents out into the atmosphere. The only reason I can figure it was originally a recirculated system was to make it so there was no noise. Now do we need one for our TB's? Who cares! I will be putting one on my because I just dropped $2000+ on a turbo and I will do what I can to extend the life of my turbo.

 

[captndave737]

I have one with a MAF, vented to atmosphere and Ive never had a problem. I do have a stock intercooler and turbo so it may be different with other combo's.

My original turbo lasted around 30K before the bearings were shot and I replaced the center section. Put on the BOV, or as ATR marketed them Sneeze Valve and the new center section has been on the car for 190k and is well within specs. Didn't change the way I drive, type of oil or anything else.

 

[Boostian]

I have one with a MAF, vented to atmosphere and Ive never had a problem. I do have a stock intercooler and turbo so it may be different with other combo's.

My original turbo lasted around 30K before the bearings were shot and I replaced the center section. Put on the BOV, or as ATR marketed them Sneeze Valve and the new center section has been on the car for 190k and is well within specs. Didn't change the way I drive, type of oil or anything else.

Does yours let all boost out or do you still get compressor flutter?

 

[1952ray]

Does yours let all boost out or do you still get compressor flutter?

I have never heard of anyone having flutter and or surge with a stock intercooler and stock turbo. I have had my car since new. I only started to have the issue when I got a front mount and bigger turbo. Like everyone else

 

[Fast4Ward]

this is how I have mine.

 

[Boostian]

Ok Fast4Ward, that is what I need to see. Couple questions:

First, mine is mounted close to the turbo and not recirculating (not going to make it recirculating). What vacuum source did you use?

Second: the bottom valve and vacuum line. What is it and where does it go. Mine is open right now (didn't come with the second valve)

Finally: how much did you adjust the set screw on top? Mine is backed almost all the way out and still doesn't seem "loose" enough?

What does yours sound like when you let off the throttle? Does it expel all the air?

 

[nolanator]

Hey everyone,
I skimmed through this thread and caught the jist of it i think. This is an inevitable subject on any forum regarding turbocharged vehicles. re-circulating the blowoff valve is the way to do it, not because of the noise or anything like that, but because the MAF sensor is sending information requesting a specific amount of fuel while taking into consideration the air that is currently in the system. When you vent to the atmosphere, the MAF doesn't know that the air never made it to the engine, so your mixture will be rich for short periods of time.

The negative effects are negligible and your car isn't going to blow up because of it, but it is something to consider if you are looking to run your car under the safest conditions.

Secondly, if you are going to run a blowoff valve or bypass valve, you want it to be as close to the throttle body as possible, not right in front of the turbo. Again, not a big deal, but it will do less to impede the flow of air.

 

[BuickMike]

Hey everyone,
I skimmed through this thread and caught the jist of it i think. This is an inevitable subject on any forum regarding turbocharged vehicles. re-circulating the blowoff valve is the way to do it, not because of the noise or anything like that, but because the MAF sensor is sending information requesting a specific amount of fuel while taking into consideration the air that is currently in the system. When you vent to the atmosphere, the MAF doesn't know that the air never made it to the engine, so your mixture will be rich for short periods of time.

The negative effects are negligible and your car isn't going to blow up because of it, but it is something to consider if you are looking to run your car under the safest conditions.

Secondly, if you are going to run a blowoff valve or bypass valve, you want it to be as close to the throttle body as possible, not right in front of the turbo. Again, not a big deal, but it will do less to impede the flow of air.

Well said. You make a real good point about the BOV being close to the TB. Every other car I've seen has it plumbed after the IC.

 

[Fast4Ward]

Ok Fast4Ward, that is what I need to see. Couple questions:

First, mine is mounted close to the turbo and not recirculating (not going to make it recirculating). What vacuum source did you use?

Second: the bottom valve and vacuum line. What is it and where does it go. Mine is open right now (didn't come with the second valve)

Finally: how much did you adjust the set screw on top? Mine is backed almost all the way out and still doesn't seem "loose" enough?

What does yours sound like when you let off the throttle? Does it expel all the air?

here's the pdf page. http://static.summitracing.com/global/images/instructions/raptor.pdf
tight down 3/4 of the way. light throttle will sometimes and rarely should give you the horse sneeze. half to full should give you an audible
phhhft of pressure back routing. see how that works.
vacuum is off one of the ports by the pressure regulator. I will have to look.
however you should redo the piping. closer to the throttle body is best.

 

[Boostian]

This is getting off topic real quick. I'm just trying to get mine to work properly.

 

[Boostian]

here's the pdf page. http://static.summitracing.com/global/images/instructions/raptor.pdf
tight down 3/4 of the way. light throttle will sometimes and rarely should give you the horse sneeze. half to full should give you an audible
phhhft of pressure back routing. see how that works.
vacuum is off one of the ports by the pressure regulator. I will have to look.
however you should redo the piping. closer to the throttle body is best.

Thank you. I don't have the second line hooked up. I think doing that as well as a better vac source is needed. I am getting the pulsing they speak about.

Thanks again.

 

[corsair231]

Without getting into the debate as well, BOV were designed for standard shift cars. It helps keep the turbo spinning while shifting gears. So when you release the throttle and it closes, pressure is released so that the pressure does not try to go back through the turbo, slowing it down. .

Hey everyone,
I skimmed through this thread and caught the jist of it i think. This is an inevitable subject on any forum regarding turbocharged vehicles. re-circulating the blowoff valve is the way to do it, not because of the noise or anything like that, but because the MAF sensor is sending information requesting a specific amount of fuel while taking into consideration the air that is currently in the system. When you vent to the atmosphere, the MAF doesn't know that the air never made it to the engine, so your mixture will be rich for short periods of time.

The negative effects are negligible and your car isn't going to blow up because of it, but it is something to consider if you are looking to run your car under the safest conditions.

Secondly, if you are going to run a blowoff valve or bypass valve, you want it to be as close to the throttle body as possible, not right in front of the turbo. Again, not a big deal, but it will do less to impede the flow of air.

These two post sum it up pretty well. They were mainly necessary for manual cars. The reason for recirculating is two fold. First the MAF has already measured the air and the computer has added fuel to match. When vented to the atmosphere the fuel is still there and the car goes instantly rich. Not a problem for our cars since when we lift throttle we are slowing down but on a stick car that has to lift throttle to shift it can cause a stumble that can slow the turbo spooling back up. The second reason is by recirculating you get a positive pressure for an instant and it gives a little head start on airflow to re-pressurizing the intake letting the car get back into boost as quick as possible. At least this is the theory the DSM guys have used for years.

 

[captndave737]

Does yours let all boost out or do you still get compressor flutter?

I dont get any flutter.

 

[captndave737]

I have never heard of anyone having flutter and or surge with a stock intercooler and stock turbo. I have had my car since new. I only started to have the issue when I got a front mount and bigger turbo. Like everyone else

I have mine mounted on the intercooler just after the turbo. In a few months I'll be starting a frame off build and after reading all of this thread I'm planning to set it up like Fast4Ward since I'll be going with a FMIC and bigger turbo. Boat towing days are coming to an end.