Hey boost freaks, I just got a Greddy Type S bov and got a couple of questions/comments.

First off, how much do you guys that have this bov adjust the spring? I have it set very soft, and when I let off the gas, I still get compressor surge (that whew whew whew sound).

Second, after it blows off, I get a little whistle sound from it (kinda funky sounding)

Third, do you recirculate it, or run it open. I tried both ways and it doesnt really make a difference. At first with it open, the car would want to stall, and even did a few times, but I found the reason why, and it wasnt the BOV, I had a vacuum leak. Anyway, just curious if I should recirc it or not, I cut up my hands pretty bad trying to get the stock recirc hose on this thing. :)

def recirculae it, it will cause drivability issues(stalling and rough idle) the sound you are hearing is normal for the BOV being open to the air..You dont want it too loose cause that will cause a vacuum leak. I for some reason get compressor surge a little too, if anyone has any info on that i would love to hear it. Not much compressor surge just on lower boost( IE press gas a little till start to hear spool then let off) thats when i ear the surging but between shifts and boosting hard i dont hear any.

Make sure you have an adquate vacuum line going to it..

Ok, I ran the vacuum line that goes to the charcoal canister straight into the BOV, no more T in there now. The spring is on the softest setting right now, and I have it recirculated. No more whistle sound, but like Tom mentioned, I also still get some compressor surge when i let off the gas at low/no boost.

oh well.

Crank the adjustment screw all the way down. The valve will open with vacuum. You do not want it to open under boost.

I GUARANTEE that the following will solve your compressor durge problems. I have done this numerous times on many cars and it wroks flawlessly.

1. Take the BOV apart by removing the allen head screws. There are 2 springs inside....a small one (inner) and a larger one (outer).

2. Remove the outer one and set it aside.

3. Reassemble the BOV with only the smaller spring inside.

4. Wrap the adjustment screw with an adequate amount of Teflon tape.

5. Rent ot buy a hand held vacuum pump. Attach the vacuum hose from the pump to the upper nipple of the BOV.

6. Start squeezing the pump and note at what vacuum level the plunger BEGINS to lift from its seat.

7. The goal here is to get it to BEGIN opening at 10 inHg of vacuum. If it starts to open at 5 inHg, then tighten the screw down and retest. Conversely, if it opens at 20 inHg, loosen the screw and retest.

8. Continue to adjust and test until you get a reading of close to 10inHg as the BEGINNING opening point. With this setting, the valve will be fully open at around 15-18 inHg of vacuum.

9. Setting it this way requires you to recirculate the BOV, as the valve will be open at idle. Remember your engine will make about 17-22 inHg of vacuum at idle, which is more than enough to open the valve.

10. If you cannot get the adjustments right using this method, then repeat using the larger spring instead. I have always had success with only the small spring in the BOV.

11. What you have essentially done here is make it require less vacuum force to open the valve. This will decrease the likelihood of compressor surge and the valve will open sooner and be more responsive.

12. If you do not recirc, then you will need to set the valve to begin opening at about 25 inHg. This setting will be less responsive and CAN result in compressor surge.

13. As a test to the validity of this process, hook up the vacuum pump to a stock DET BOV and see what amount of vacuum is required to make it start to open.

Good luck,

Yep, top notch advice/instruction from Jay...... always works like a charm! Jay is definately a real asset to the forums and mailing lists.

Thanks for the advice Jay, I will mess around with it this weekend. I will see what its at now with both springs, I have it recirculated, but would like to run it open. I just hope it doesnt whistle all the time, that gets annoying. :)

Now I'm a newbie but from what I understand you recirc the air because the air that is blowing out has already gone thru the MAF and the ecu is adding fuel for that amount of air so if it gets dumped out the car runs rich( for a short time anyway)

correct

thanks for the post. Ill be using this info in the morning.....Josh

This is stupid, but what connects to the nipple on the lower half of the unit? I am running open air till I get it running right. However, I no longer have idle problems running open air, so I may keep it like that a while.....Josh