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Atmospheric Venting Bovs And R34 Gtrs. Who's Done It?

Iron Mike
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Iron Mike Proficient

Iron Mike

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I've heard from a number of places that installing BOVs that aren't recirculating/plumb-back onto GTRs can be quite troublesome - stalling at idle, massive fluctuations in air/fuel ratios etc. I have also been told that HKS produce/d a part called the 'EIDS' that can counter this problem for those that still want an atmospheric venting BOV (albeit illegal) and that famed WHOOOSH sound!! Has anyone here ever used or installed one of these things, and what are peoples experience with aftermarket BOVs on GTRs, especially in terms of increased performance/less lag between shifts??

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500hp Community Regular

500hp

Posted
Posted

atmo blow off valves are shit, get the GFB recirculating valves much better. Also keeps cops of your back, cos there plumbed back. i dont run any blow of valves or factory bypass valve on my gtr at all and its much better.

Four - Twelve Enthusiast

Four - Twelve

Posted
Posted (edited)

Previous owner did this on my car before purchase. It was a pretty stupid mod as he chose to run a standard pfc. The symptoms you mention are true if you are running an ecu that reads off the AFM's. Apparently (yet to convert mine) this is no longer the case when you get rid of the AFM's with something like Haltech or D-Jetro etc.

I wouldn't bother with EIDS, just covert the tuning platform or plumb it back. Or save yourself the money and keep it stock.

Edited by Four - Twelve
KING87 Rising Star

KING87

Posted
Posted

I have my standard ones venting to atmo only because the piping was interfering with the ARC box. There were no adverse affects on performance or tune that were noticeable. I am also using MAP sensors not air flow meters which makes a difference when changing from plumb back to atmo.

(OO)SKYLINE(OO) Grand Master

(OO)SKYLINE(OO)

Posted
Posted

This has been covered in depth.

You will lose performance going to atmo bovs.

Keep the stock.

Theyre good for up to and over 1000hp from the cars that have been on here.

+1

Stock e-Tune Contributor

Stock e-Tune

Posted
Posted

ok, lets clear this one up.

non-recirc BOV will not cause idle issue unless its faulty or not installed correctly (airleak etc),

although it may cause 'decay to idle' mixture issues if DFCO not working or tuned/operating correctly.

manual trans vented BOV MAF tuned vehicles often exibit a puff of black smoke from the exhaust during on-boost gear changes,

but not usually as often in automatic MAF vehicles due to less throttle changes from boost to closed throttle.

The puff of smoke (incorrect air fuel ratio) is due to the loss of air that the ECU metered and sprayed fuel for that left the vented BOV to atmosphere.

The BOV regardless of venting design, releases pressure during a closed throttle condition (vacuum) where boost pressure exists between turbo and throttle plate.

When a recirculating BOV is installed the air venting from the BOV is directed back at the Turbo intake side preventing more air being meter by MAF. In a MAFless tune this is not required (in a offroad car) to be plumbed back and not an emissions issue unless the turbo is worn.

When the turbo is worn, oil contaminants can enter the atmosphere from the BOV due to worn seals, bushing, bearing etc, causing an EPA emissions compliance issue.

Whether or not BOV is installed, or its recirculating or not, total power is not sacrificed,

The only time a noticeable delay in power production (lag) may occur is due to the turbo impellers stalling.

This happens when the the engine transitions from boost to closed throttle and the excess air pressure pre-throttle body has nowhere to go but stall the turbo from spinning momentarily. note: this also stalls the exhaust flow creating stale burnt mixture to be processed by the engine for several rpms. This inturn increases the time it takes to get back on boost and accelerating through the selected gear.

If the engine can not run correctly with a venting BOV then it most likely had issues to begin with, they just became more obvious.

Most issues with venting to atmosphere BOV's are with MAF tunes not MAP/MAFless.

MAF tuned vehicles require more considerations in intake airflow design and tuning to minimize these issues.

I've tuned many RB's at WSID drag/circuit & Wakefield. I must say I much prefer the MAF setups for flexibility reasons, I haven't come across a MAF tuned vehicle with a vented BOV we couldn't sort out. The MAP/MAFless tunes are great also but tend to require more tweaking to stay on song for every occasion.

I hope this helps..

I've heard from a number of places that installing BOVs that aren't recirculating/plumb-back onto GTRs can be quite troublesome - stalling at idle, massive fluctuations in air/fuel ratios etc. I have also been told that HKS produce/d a part called the 'EIDS' that can counter this problem for those that still want an atmospheric venting BOV (albeit illegal) and that famed WHOOOSH sound!! Has anyone here ever used or installed one of these things, and what are peoples experience with aftermarket BOVs on GTRs, especially in terms of increased performance/less lag between shifts??

Four - Twelve Enthusiast

Four - Twelve

Posted
Posted

ok, lets clear this one up.

non-recirc BOV will not cause idle issue unless its faulty or not installed correctly (airleak etc),

Not meaning to take away from your credibility, but remember that this is the exact reason that hks eids exists.

Refer bottom of page;

https://www.hks-power.co.jp/en/product/blow_off/option/index.html

The puff of smoke (incorrect air fuel ratio) is due to the loss of air that the ECU metered and sprayed fuel for that left the vented BOV to atmosphere.

This relates to why stalling occurs - air passes the afms that is subsequently lost to the atmosphere. The extra fuel that you talk of is a compensation for the air that is expected to be in the engine, causing it to run very rich - hence the smoke. This scenario also relates to the stalling issue, as when the car is slowing down/ stopping, the air is once again lost and air that the car thinks is going to the combustion chamber, doesn't arrive. The car hunts idle and can even stall.

Iron Mike Proficient

Iron Mike

Posted
  • Author
Posted (edited)

Thanks Stock e-tune and Four-Twelve. Very informative and knowledgeable discussion. Luke GTR these forums have been around for quite some time now and I'd assume that pretty much everything pertaining to GTRs has been discussed at some point. Given this I did a brief search though didn't find what I was looking for hence my post.

Edited by Iron Mike
luke gtr Grand Master

luke gtr

Posted
Posted

In a MAFless tune this is not required (in a offroad car) to be plumbed back and not an emissions issue unless the turbo is worn.

When the turbo is worn, oil contaminants can enter the atmosphere from the BOV due to worn seals, bushing, bearing etc, causing an EPA emissions compliance issue.

not just with a worn turbo.

the pcv is generally plumbed into the intake, this vents pcv gases to atmosphere.

same as having a pcv system that is vented straight to atmosphere, its illegal in most(if not all) states.

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