donistook

Guys, a few of you are off base on this issue. The BPVs recirculate air back to the intake side of the compressor wheel. This air has already been measured as it has gone through the system. Some of you are concerned about losing some of this "metered air" when using a BOV and the engine going "rich". Well, using that logic, have you thought about this metered air with a BPV going back through the intake system a second time....the MAF doesn't register it because it reenters after the MAF....would the engine then "go lean"??

I don't think that this small amount of air is really going to matter, because it is just a flash.

Also, I read the concern about air going back through to the MAF....think about it,,,if that was a concern, it would be more of a concern when using a BPV because the air out of the BPV goes right back into the intake system between the compressor intake wheel and the MAF.

Ok...a tip for THOSE OF YOU WHO WANT TO TRY IT!!....(might through a code). Pull the hose off of your BPV that goes back into the intake...meaning the rubber hose that "Ys" into the intake system. Plug the hose with something (a 1" piece of an old broom handle, anything that will seal it). Start the engine and see if it will idle and how rough it might be. Rev it up with the help of a friend while you observe. Put your hand over the exposed opening of the BPV and see if you can feel air coming out...you should. Now, clamp off both of the small lines going into the top of each BPV with something,,,pliers, c clamp, anything to shut off the vacuum going to the valve which will cause it to close...Does the air stop coming out and does the engine smooth out??

This may explain why some trying BOVs may have had problems....the valve was open at idle.

I will not be around to read responses to this as I am flying to Canada in the morning to race at MOSPORT this weekend.

I hope that these threads are informative.

Keep in mind that I am not advocating anyone to go to BOVs, but merely trying to clear up some misinfomation about them. There is no real mystery to them. The BPV is a better system for everyday driving from certain stanpoints....but the BOV is better for total performance under certain applications.

Best wishes........Don

No More B5 S4

Thanks for the info! :-)

ROCKCENTER

who else just visited the HKS page?

Jason @ Streetwerke

Don, I have some valves to send you for trial. Interested?

gsxtos4guy

i found this to be true with a few Greddy bov valves that i have used in the past. I tried everything wound opening the valve and popping in a stiffer spring. This was on a eclipse. Now I've been tinkering with the idea of installing two Relief Valve Adapter to protect the car from over boost. http://www.greddy.com/products/blowoffvalves_frame.htm<ul><li><a href="http://www.greddy.com/products/blowoffvalves_frame.htm">http://www.greddy.com/products/blowoffvalves_frame.htm</a</li></ul>

gsxtos4guy

they work end of story, no leaks. Only problem is fitment, they are huge.

jyoteen

Good luck at MOSPORT!

wishbone

Maybe I'm thinking about this incorrectly but if the air recirculates it's not going into the system a "second" time. It's metered air that is still contained in the system. As you said, it recirculates after the MAF. This will insure that more air is not pulled in. If you vent the air to the atmosphere you're going to create a vacuum and suck more air past the MAF that isn't being used by the car at all. This in theory is what all the "rich" arguments are about. The system wouldn't run "lean" with recirculated air because the ECU knows exactly how much air has passed by the MAF and should be able to accurately provide the right fuel mixture. However, if you vent and pull more air in. The ECU will think there is an excess of air in the system that actually isn't there at all. It's exactly the same reason the car will run rough at idle if you use a BOV that doesn't have enough spring tension. It will leak into the atmosphere and create a rich condition that confuses the ECU and makes your vehicle idle rough..

I have tried several BOVs with varing spring tensions myself without great results. I might even experiment with the turboXS ones because that's the only brand I haven't tried at this point. One thing I worried a lot about was the additional pressure put on the system. As you mentioned yourself you had hoses blowing off. Maybe this is due to the fact that the divert location does not provide enough flow? I always thought it was because you had to make the spring tension so tight that it needed too much pressure to open. That's another thing that always bothered me. You're changing the design all together. The stock system only uses vacuum to open the valves. Most BOV only valves require boost pressure and vacuum to create a differential condition...

Sorry that was long winded and you'll probably not get a chance to read it. Good luck and MOSPORT and I ALWAYS enjoy reading your posts. I don't mean to sound like I question your knowledge I'm just trying to understand it a little more myself.

regards...
joshua

MoBrazen

Hmm, GFB Hybrids perhaps? Just a guess...

EkSiPd

do they make those for the S?