DropTopTwin

I've searched in different forums and it seems like there are no clear cut answers surrounding the BOV and recir. valves.

Some say the BOV will make you run rich. Others say it's for a split second so it doesn't matter.

Some say the BOV will make you change the plugs faster. Others says it's no big deal since it's only sooner by couple of thousand mile.

Some say the stock recir valve can handle above 25lbs while other say they leak boost in high boost conditions.

So I'm a little lost what to believe. For 600whp, I'm told BOVs are needed but some people are saying stock recir valves are fine.

Can stock recir valve handle 600whp or should I switch to BOVs?

snwbrderphat540

supposedly they can handle alot of power. and atmospheric dumping BOV's will run the car rich for a split second because you go from full boost with the injectors keeping up with them then suddenly you let off the throttle, injectors still dumping in fuel but suddenly no power air pressure = rich until the BOV's close back up and the injectors are running how they should be for idle. sometimes it causes the car to stall if you don't stick it back in a gear or give it some throttle. not a big deal either way.

DropTopTwin

What I'm trying to find out is if the stock recir valves will be fine with 600whp. Some are saying they will be fine while just as many(seems like anyways) are saying I need to get BOVs. I'm not really concern with split second rich condition and I don't want to spend the money for the psssishh sound if the stock recir valves will handle the power.

snwbrderphat540

why dont you just try it out. worst comes to worst you get a little compressor surge at full boost or they dont hold the boost and you run a bit rich till you upgrade.

DropTopTwin

I'm in need to replace the right side recir valve. I don't know how but we are missing one... One of couple of problems I'm having with my Z...

Anywho, so I'm thinking of just replacing them with stockers but then I'm getting advises from people to go with BOVs because they can handle high boost. I don't want to get the stockers and then realizing I need the BOVs. On the other hand if the stockers can handle the high boost then I rether use the recir. The problem is there are just as many people for and against both parts, and I need to order them now. I just don't want to end up buying both of them.

ZLover4Life

I'm too busy to read all of the replies, but if Greg Dupree can push about 30psi on HUGE turbos (yes, he's well over 600rwhp) and run 9's on stock recirculation valves, then I cannot believe that BOV's are EVER necessary for a Z32. BOV's are for aesthetics only.

And if it matters, I have stock recirculation valves and about 550bhp @ 20psi right now (will have over 600hp when I upgrade to 3" exhaust and dual pop with larger injectors).

If you're going to get BOV's, get HKS or Tial.

DropTopTwin

I've read that too but then you some people stating the recir valve leak at high boost. I never had any problems with recir valves when my car was running 485whp and I rather keep them oppose to having BOVs. I don't want the unnecessary attention with the noise and if the stock unit works just as good or better then I would rather keep them.

I was just confused and concern because of the different opinion on the BOVs.

Which turbos and what size injectors are you running in your Z?

ZLover4Life

HKS GT2530's with 555's at the moment (injectors and the single intake/2.5" exhaust being the remaining bottlenecks on my car). Ask these people for evidence of leaving OEM recirculation valves... they won't have anything other than "I heard from this guy"... and if you ask that guy, he "heard it from this other guy."

DropTopTwin

Thanks for the info man. I'll be ordering new recir valves today.

Which duel intake are your considering? Are you going witht he JWT design or the Doolz design? Other then the lack of low load drivability hose, what are the advantages or disadvanages does the Doolz have over the JWT design or are they pretty much the same?

ZLover4Life

Doolz is a poor design and will not flow as much as Dual Pop (it's narrower at the intersection than Dual Pop). With an AFC and 2 MAFs, the Dual Pop will outperform the Doolz and also have no drivability problems.

DropTopTwin

How come only some people have problems using the duel pop? I've read where people have used the SAFC with the 2nd MAF while some people don't have any issues without them.

And which SAFC should be used or will they all work for this?

ZLover4Life

"Which SAFC should be used" is an incoherent question. S-AFC is a product name, not a product type. The S-AFC is made by A'pex-i, and that's the generally recommended product due to ease of use, cost, versatility, etc. Any AFC should be able to splice two MAF signals though.

The people who have problems with dual pop are people who don't have the system installed properly (like many single pop owners as well) or don't have a second MAF. The second MAF+AFC generally eliminates the problems related to the system (any other problems are not the fault of the intake).

snwbrderphat540

they make the S-AFC and S-AFCII so... technically... you know. haha

also they got the new HKS Neo AFC which looks very nice and easier to use. havent heard anything about them yet.

DropTopTwin

Due to my extreme ignorance on this subject I may ask a dumb question of 4. lol

As Snow've mentioned there are several different models and I didn't know if all of them could do it.

One more question please.

What kind of hp numbers would require you to move up from the 555?

ZLover4Life

As a general rule of thumb, the cc/min of the injectors is about as much rear wheel horsepower as they can handle... so 555cc/min injectors are done in the area of 555rwhp. The reason I like A'pex-i's boost controller (and any AFC can do this as well) is that you can monitor injector duty cycle... if you ever see them go above 90-95% at WOT, it's time to upgrade to larger injectors. And if they reach 100% and you're still accelerating, stop.

DropTopTwin

Thank you sir.

snwbrderphat540

don't know why but this made me LOL. and yeah the AFC's by A'pex-i do have some amazing read outs... RPM knock throttle duty cycle. etc... its like a beast guage all in one. and it tunes!

DropTopTwin

One last question.

Between JWT and Z1, which would you choose for the duel intake(not the doolz but the JWT look a like from Z1) and the chip upgrade?

ZLover4Life

If I considered Z1 to be a viable option, I would've said so. Certain companies need to stop ripping other companies' designs off... if you want to spend money on a product that had no R&D, they just bought a JWT kit and had it cheaply replicated by some nameless company, get the Z1 kit - you'll be supporting idea theft and production of knock-off parts. If you want to support Z32 part development by buying a product where the money goes to a company who actually develops new parts, get JWT. And nobody in their right mind would get an ECU other than JWT.

And I'm just gonna say it - Z1 should not be in business anymore, and nobody should visit that website when they're looking for parts.

DropTopTwin

Thanks for all your help.

I'll be ordering the JWT duel pop and ecu, but I am guilty for supporting design thief.

KasbeKZ

it seems that that is the consensus on tt.net. it's going to take a bad experience for me to stop liking them though. granted, i'll stay away from their knock off parts, and there are actually a lot of things i wouldn't get from there, but, i consider them good for a lot of things at this point. perhaps i'll change my mind soon....

CanyonCarver

If Mike Smith was smart, he would have taken his design and had the manifolds made in china. Then he wouldn't have left himself open to what happened. If he had marketed his manifolds at the reasonable price that the market would bear, other business people wouldn't have seen the benefit of investing in the tooling and associated costs to try to compete, or undercut his prices.

If AMS didn't come out with a competing manifold design, someone else would have. Guaranteed. It is how the world works.

ZLover4Life

^ Doesn't make it right. And *quality* parts aren't made in China... so I absolutely disagree with the statement that Mike should've had them made there.