BOV - recirculate or not?
#45
Supporting Vendor
![](/mt2011/images_td/ranks/vendor.png)
Thread Starter
iTrader: (3)
Join Date: Jul 2006
Location: San Diego
Posts: 3,303
Total Cats: 1,216
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Originally Posted by bripab007
The Bosch unit leaks at idle, but, because it recirculates, it's not a matter of any concern.
-Ryan
#46
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Not a cause for concern because it recirculates, so, yes, no idle problems. When you're under boost, it's held shut by the pressure on the signal line. While you're idling or in partial vacuum or light boost, it can leak a little bit, which is fine. That's what it's meant to do.
Edit for spelling.
Edit for spelling.
Last edited by bripab007; 07-06-2006 at 07:15 AM.
#48
Boost Czar
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/admin.png)
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,688
Total Cats: 4,113
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I think I'll add more riviting multimedia to the discussion. I made two quick videos of my recirculating bov as heard while driving with the top up.
http://www.rev2red.com/images/cars/CIMG0108.AVI
http://www.rev2red.com/images/cars/CIMG0109.AVI
http://www.rev2red.com/images/cars/CIMG0108.AVI
http://www.rev2red.com/images/cars/CIMG0109.AVI
#50
Boost Czar
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/admin.png)
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,688
Total Cats: 4,113
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Originally Posted by firedog25
Sounds about as loud as my VTA with filter, not very loud at all, just enough to hear if you're listening.
#52
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Originally Posted by ThePass
Not a matter of any concern as in, because it recirculates it doesn't cause idle problems? Does the leaking cause any performance losses? It seems like if its leaking it can't be good...
-Ryan
-Ryan
#56
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
ThePass
If you read the text a little closer on the link that you supplied you will see that it says
"The piston is actually fitted with a piston ring for a perfect seal. Combined with a well-chosen spring, this means the valve can be used on a car that uses a MAF or AFM to measure airflow."
The most important part of that statement is "with a well chosen spring", a perfect seal can be detrimental in a VTA BOV on a MAF car if the spring rate isn't correct. There are piston type valves on the market that work because the tollerances are so loose that the vacuum will not lift the piston at idle. If the valve is designed with an airtight seal, such as ours and the GFB that you listed, the spring tension needs to be chosen for the application. That being said, I never recommend a VTA valve on a MAF car. Which leads me to the following...
firedog25
Do you know the color of the spring in your valve? I can send you the next stiffer spring to see if that cures the problem. Or we can go another route and get you the right valve for your application. If you prefer to have VTA you would need to use our 004:
http://www.forgemotorsport.com/conte...roduct=FMDV004
Or if you wish to recirculate go with the 007:
http://www.forgemotorsport.com/conte...oduct=FMCL007P
Just ship us the 003 and I will send you your choice of these two valves with no additional charge.
Pat
If you read the text a little closer on the link that you supplied you will see that it says
"The piston is actually fitted with a piston ring for a perfect seal. Combined with a well-chosen spring, this means the valve can be used on a car that uses a MAF or AFM to measure airflow."
The most important part of that statement is "with a well chosen spring", a perfect seal can be detrimental in a VTA BOV on a MAF car if the spring rate isn't correct. There are piston type valves on the market that work because the tollerances are so loose that the vacuum will not lift the piston at idle. If the valve is designed with an airtight seal, such as ours and the GFB that you listed, the spring tension needs to be chosen for the application. That being said, I never recommend a VTA valve on a MAF car. Which leads me to the following...
firedog25
Do you know the color of the spring in your valve? I can send you the next stiffer spring to see if that cures the problem. Or we can go another route and get you the right valve for your application. If you prefer to have VTA you would need to use our 004:
http://www.forgemotorsport.com/conte...roduct=FMDV004
Or if you wish to recirculate go with the 007:
http://www.forgemotorsport.com/conte...oduct=FMCL007P
Just ship us the 003 and I will send you your choice of these two valves with no additional charge.
Pat
#57
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
When they say it can be used with a MAF/AFM car because of the well-chosen spring and seal, they just mean it won't leak at idle. If it's a vent-to-atmosphere, it'll always run rich between shifts in addition to possibly leaking at idle, unless that well chosen spring happens to be on so stiff it renders the piston useless...at which point you no longer have a functioning bypass valve
![](https://www.miataturbo.net/images/smilies/smile.gif)
#58
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Well I figured I might as well contribute my experience w/ VTA and recircs as well as the BOV of choice for me.
First of all let me say I ran a eclipse GSX @ 17 psi running several different BOVs. First I had a turbo XS RFL (really ...loud). I blew off about 5 feet from some lady and she banged her head on her roof cause it made her jump (she was bent over gettin something out of the seat). As great as that moment of my life was, the rest sucked. My car ran rich and dumped fuel between shifts and also had a very crappy idle due to the MAF trying to compensate for the air.
Next I tried the 1g DSM metal BOV. Let me tell you, if your looking for a SOLID (17-20psi uncrushed) bov.. this is it. Its SUPER quiet and you can get it ALREADY flanged onto the 1g DSM pipe section for roughly 40 shipped off dsmtuners. com.
I however, upgraded my pipes and transitioned to the Greddy Type-S (no longer made I guess). This BOV held boost awesome and possessed I would describe as a "middle" loudness sound. It sounded like a "Ka-*****" between shifts. I ran it at 14 PSI and it held fast. If I could find one again I DEFINITELY will use this on my turbo miata.
Hope this helps w/ your selection.
First of all let me say I ran a eclipse GSX @ 17 psi running several different BOVs. First I had a turbo XS RFL (really ...loud). I blew off about 5 feet from some lady and she banged her head on her roof cause it made her jump (she was bent over gettin something out of the seat). As great as that moment of my life was, the rest sucked. My car ran rich and dumped fuel between shifts and also had a very crappy idle due to the MAF trying to compensate for the air.
Next I tried the 1g DSM metal BOV. Let me tell you, if your looking for a SOLID (17-20psi uncrushed) bov.. this is it. Its SUPER quiet and you can get it ALREADY flanged onto the 1g DSM pipe section for roughly 40 shipped off dsmtuners. com.
I however, upgraded my pipes and transitioned to the Greddy Type-S (no longer made I guess). This BOV held boost awesome and possessed I would describe as a "middle" loudness sound. It sounded like a "Ka-*****" between shifts. I ran it at 14 PSI and it held fast. If I could find one again I DEFINITELY will use this on my turbo miata.
Hope this helps w/ your selection.
#60
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Originally Posted by patty AT forge
T
firedog25
Do you know the color of the spring in your valve? I can send you the next stiffer spring to see if that cures the problem. Or we can go another route and get you the right valve for your application. If you prefer to have VTA you would need to use our 004:
http://www.forgemotorsport.com/conte...roduct=FMDV004
Or if you wish to recirculate go with the 007:
http://www.forgemotorsport.com/conte...oduct=FMCL007P
Just ship us the 003 and I will send you your choice of these two valves with no additional charge.
Pat
firedog25
Do you know the color of the spring in your valve? I can send you the next stiffer spring to see if that cures the problem. Or we can go another route and get you the right valve for your application. If you prefer to have VTA you would need to use our 004:
http://www.forgemotorsport.com/conte...roduct=FMDV004
Or if you wish to recirculate go with the 007:
http://www.forgemotorsport.com/conte...oduct=FMCL007P
Just ship us the 003 and I will send you your choice of these two valves with no additional charge.
Pat