JustJeff

iTrader: (13)

Did some searching but came up empty thus far...

My OEM BOV (port air bypass valve as the FSM calls it) is dead. Technically according to wikipedia the factory part is compressor bypass valve.
http://en.wikipedia.org/wiki/Blowoff_valve

Background on the car.
I've got an 89 vert with a S5 JDM 13B. 3" exhaust w/presilencer, FCD, custom TID (3-4"), N370 ECU. FD fuel pump..hopefully geting the rewiring mod done this weekend. I've got 800cc injectors going in the secondaries today. Still deciding on engine/fuel managment. PSI can get up to 12 psi, though I don't push the car for fear of lean mixture and detonation. The shop that did the work had me using an N390 port air bypass.

The information I couldn't find is how compatible are the different year port air bypass valves? Also, are the 3rd gen rated for higher PSI?

I'm not all that interested in aftermarket BOVs. The only model that I've found that feeds back into the intake is:

TURBOXS Bypass Valve -Type H34 offered by Corksport.com

However it looks like this one may also...
HKS Blow Off Valve -Standard Bypass Vavle

Both are located on Corksports site

Am I correct in thinking that a BOV that vents to atmosphere will create a rich A/F mixture?

JustJeff

iTrader: (13)

No one has info on differences betweenS4, S5, and 3rd gen OEM port air bypass valve? I seem to remember that the N390 bypass valve is cosmo...but had previously been told that N390 was FD

Anway, ambien is giving me heavy eyes

staticguitar313

iTrader: (2)

Greddy Type RS with adapter pipe, goes for about $230shipped on ebay

red_dragon

iTrader: (10)

Does the RS vent to atmosphere? I've been looking to get one but I'd been warned that atmospheric ones will confuse the MAF and the engine will run rich for a while. I really like the RS sound though...

JustJeff

iTrader: (13)

Here it is @ RX7store
http://www.rx7store.net/product_p/gr...%20r%20bov.htm

I'd only be interested in an aftermarket one if it helped the car perform better. That and everything I've read so far says atmospheric ones will cause a rich mixture if your using a MAF.

Longshoe

iTrader: (2)

I wouldnt get another one unless you were running more than say to lbs of boost. I forget when the stock bypass valve stops being efficent. Valves that vent to the atmosphere cause a temporary rich condition because air has already passed through the AFM and the ECU has already calculated how much fuel the engine needs based on the amount of air that passed through the AFM. When the throttle blades close and the excess air is vented into the atmosphere, the ECU has already injected fuel for that air. This is what causes the rich condition (and sometimes flames out the exhaust at high rpm shifts). A recirc valve which is what these cars have stock just reroutes the vented air back into the intake which helps a bit for the rich condition.

Its not going to damage anything if you slap a bov on there but its not going to give you any gains unless you like the noise.

JustJeff

iTrader: (13)

Thanks for the reply. I'm not really into show-n-tell performance. I'm very much function over form.

My car is very much a work in progress. JDM 13B swapped into an 89 vert, 3" exhaust, FCD, going to have 800cc injectors in the secondaries...hopefully by the end of today. But no fuel or boost management yet. I can get 12psi..seen it up to 15psi, but I never push the car that hard for fear of lean mixture. After I get some fuel and boost control I'll drive it more...um...heavy footed. But I've still got some learning to do before I buy any electronic gadgetry.

Mankdrake 2661

iTrader: (8)

Aftermarket ones can hold the higher boost better and, for the most part, the spring tension can be adjusted. I've got a Greddy RS vented to atmosphere and it only "runs rich" for a split second. Just long enough to get a POP out of the exhaust.