Blow off valve question

[tracy]

I have a Greedy blow off valve on my TTA. Sometimes when lifting off the throttle, the car shudders and I hear short bursts of air escaping. I am assuming this is the blow off valve doing this.

Would you agree and would reducing the spring pressure also reduce my boost.

I'm tempted to remeove the blow off valve altogether.

 

[86brick]

Get rid of the blow off valve and if somebody tells you that you need one tell them BLOW ME!!!!!!

 

[tracy]

I think you're right. there's a vac line going to the BOB. What do I do about that - just cap it?

 

[Brooks]

If you decide not to use the BOV you will likely have to remove it entirely or cap the BOV outlet. If you pull the vacuum line and stow it the BOV will lift when boost exceeds spring pressure and bleed air off.

For what ever reason, the subject of BOV's tends to bring out the worst in people here on turbobuick.com. I would suggest looking for an import board geared toward tech before tossing it in the can.

Good luck in any case,


Charles Brooks

 

[GNGSX]

The nipple on the top of the BOV needs a vacuum source that is after the throttle plate. The lower nipple needs a vacuum line coming from a boost source such as the compressor housing. You could leave the lower nipple disconnected, but it works best hooked up. If you decide to remove the BOV, I might buy it from you.

 

[Taffy]

Most of the GN guys do not like the BOVs. That is cool. Most of the import guys do not like a lot of the things that the GN guys are doing. I guess I am lucky that I have a little of both.

Make sure the top of the BOV has an air signal. Like GNGSX said, you do not have to use the bottom inlet of the BOV. Running both makes it easier for the BOV to lift on the lower boost cars. If you are running more than 10 psig boost, just use the top inlet.

You acn adjust the spring to hold more boost, but only a little more boost. It is used mainly to depict how quickly the valve closes after it opens. If you run into the problem of your car always stalling after it blows off, tighten the screw, that will make the BOV close sooner, therefore letting less air out, yet still letting most of the excess pressure out.

If you have any other questions, contact me directly so as not to get all of the negative comments.

 

[alb84]

You did not say where the air that it is blowing off is going. It needs to be plumbed back into the intake between the Tbody and the maf. That air has been metered by the maf and needs to stay in the engine. If it just blows off to atmosphere, the engine will stumble because the ecu air calculations are wrong. Bovs are a great way to reduce forces on the turbos impeller, bearings, and shaft. It should be adjusted to be in synchronicity with the waste gate for the best results. If I was running a high dollar turbo I would want one for sure. Later.......Danny

 

[Taffy]

Originally posted by alb84
You did not say where the air that it is blowing off is going. It needs to be plumbed back into the intake between the Tbody and the maf. That air has been metered by the maf and needs to stay in the engine. If it just blows off to atmosphere, the engine will stumble because the ecu air calculations are wrong. Bovs are a great way to reduce forces on the turbos impeller, bearings, and shaft. It should be adjusted to be in synchronicity with the waste gate for the best results. If I was running a high dollar turbo I would want one for sure. Later.......Danny

Some GN owners have noticed that even blowing off the air to atmosphere, their cars did not stall. That is one of the things that you can mess with by changing the pressure on the spring.

I am going to be making a BOV kit that routes the air back to the turbo, after the MAF. There is a guy around the corner from me that has a Mandrel bender. Now that I have a little bit of funding, I can actually start on it.

 

[alb84]

Yes it is true that by adjusting the spring you can adjust out some of the stumble, even to the point where you can't feel it.......But the fuel air calculation is still wrong. Also the more you adjust it out with the spring, the impeller takes more of the shock. The import crowd places a high value on the sound the blow off valve makes, not on the protection it provides for the turbo. They even sell fake blow off sound for those that don't have turbos. It is probably time for the turbo Buick community to go ahead and realize that bovs are a good thing for a street driven car. If all you do is run the 1/4 mile, then don't bother. Taffy is going to make a kit, so he should be supported in his effort to protect our turbos. Bling bad.....Protection goood. Later...........Danny

 

[Taffy]

Originally posted by alb84
Yes it is true that by adjusting the spring you can adjust out some of the stumble, even to the point where you can't feel it.......But the fuel air calculation is still wrong. Also the more you adjust it out with the spring, the impeller takes more of the shock. The import crowd places a high value on the sound the blow off valve makes, not on the protection it provides for the turbo. They even sell fake blow off sound for those that don't have turbos. It is probably time for the turbo Buick community to go ahead and realize that bovs are a good thing for a street driven car. If all you do is run the 1/4 mile, then don't bother. Taffy is going to make a kit, so he should be supported in his effort to protect our turbos. Bling bad.....Protection goood. Later...........Danny

Thanks man!