Atmospheric vs Recirc Blowoff

[Chezedik]

I am about ready to purchase a blow-off valve for my setup and am having trouble deciding on whether to run an atmospheric or recirc valve. Here is what I am finding:

Pros to atmospheric: Pros to Recirc:*seemingly cheaper *supposed to be no stumbling*sounds freakin' wicked *stealthyCons to atmospheric: Cons to Recirc:*rumors of nasty stumbling *more expensive *more complicated *no PSSST!!!!

Anyone with any experience, your feedback would be welcome. Particularly, in regards to the off-throttle stumble. How bad is it? Does it happen often? Would you do it again? Which is better for performance?

[onosqv]

atmospheric & recirc will cost nearly the same, except maybe $5 - $10 for tubing and getting a return bung welded.

Depending on your current setup, atmospheric may end up costing you MORE - depending on how reliable you want it.

To run atmospheric reliably, you need either a standalone (i.e. upgrade to MAP sensor), or a Cobra Maf running blowthru. Recirc you don't.

If both are set up correctly, there is no performance difference, other that "psst". And if you are running a good turbo setup, you'll still get the "psst" in a recirc setup, just not quite as loud.

Many bov's can be run both open & recirc (for example, the hks has a recirc fitting, and so does the greddy). Each setup has their own complications, neither is more complicated since they are easier at different parts.

And if you are only considering running an open bov because it "sounds" cooler... don't turbo, sell your car, get a ford festiva, and buy this: http://cgi.ebay.com/ebaymotors/Fake-Tur ... enameZWDVW

[Chezedik]

Ha! Fantastic! Anyone else?

[C-Kwik]

*no PSSST!!!!

Very wrong. I had mine recirculated and it was quite audible. You won't hear it in many OEM turbo set-ups as the airbox is designed to decrease noise. But with an open element filter, you'll likely hear most BOV's even if they are recirculated. This is especially the case if the recirculation is not too far from the filter.

Personally, having a motor that doesn't stall all the time is a lot nicer than some BOV sound. The sound really is only for show. I preferred to show people my taillights though. Having a BOV sound was just a bonus.

[Jookmasta]

i run the open bov, and i think that its personal preference if u can get the open bov to run without issues. if ur driveability is suffering because of the open bov, then recirculate. i run an safc one and with the decel settings i take care of the issues with running an open bov. the sound really is for show but whats wrong with hearing the sound and showing people ur tailights.

[onosqv]

whats wrong with hearing the sound and showing people ur tailights.

Absolutely nothing if you can get it work rite

[Nismo_Freak]

I like the loud purge

[crzycav86]

running no bov sounds coooler guyth. so lets all do that.

[sunnys14]

i think running recirc BOV and open wastegate is better

[Kenrik]

I want the Psstt sound that way stupid ricer boys will leave me alone... (actually I think the opposite would be true lol)

[98s14inaz]

My recirc is loud as hell...I have one of those old school hks standard bov's. I have no issues with stalling or any other driveability issues. Atmospherically vented bov's are for ricers.

[Chezedik]

A lot of good points, and I do hate ricers. But there is no diff in performance whatsoever? Now what about the differences between some of the cheaper ones and the big names. Isn't it just a poppet valve, or are there subtle nuances I am missing. Are ones made by OEMs better or worse than the aftermarket ones? Why?

[onosqv]

Atmospherically vented bov's are for ricers.

Or for ppl who want minimal boost leak locations (2 added from recirc). Same reasoning for ppl who do blow thru (given they get the cobra maf and tune rite) - or map sensor. Popping an IC piping (which a lot of you guys have been through) isn't as dramatic if you have a blow-thru, given that the pipe, or in this case bov recirc hose, that popped is in front of the path.

Everything has it's own purposes, advantages, disadvantages, etc - it's up to you to prevent forest fires...

[grimple1]

Since when did the term "ricer" get applied to actual engine modifications? Tail lights, ok. Wheels, ok. Paint job, ok. BOV recirc or atmospherical, NO.

[onosqv]

Since when did the term "ricer" get applied to actual engine modifications? Tail lights, ok. Wheels, ok. Paint job, ok. BOV recirc or atmospherical, NO.

If exhausts can sound ricey... why can't bov's? touche!

[Mikoriad]

I have a daily driver VW jetta 1.8t and once I put a cone filter intake on it, I can clearly hear the rec. valve on throttle cuts. I wouldn't call it rice....

[Nismo_Freak]

Or for ppl who want minimal boost leak locations (2 added from recirc). Same reasoning for ppl who do blow thru (given they get the cobra maf and tune rite) - or map sensor. Popping an IC piping (which a lot of you guys have been through) isn't as dramatic if you have a blow-thru, given that the pipe, or in this case bov recirc hose, that popped is in front of the path.

Sure put the MAF after the turbo, that way when your pipe pops off your turbo now has zero ability to produce boost. So the wastegate never opens, and it explodes the center section.

[Chezedik]

What about OEMs versus aftermarket. I could get a 1g BOV for cheap, and if it will work just as well for my needs than I don't care. Do aftermarket valves seal any better?

[C-Kwik]

Or for ppl who want minimal boost leak locations (2 added from recirc).

That's a rather lame reason for going with open BOV. Done right, no pressurized hoses should ever come loose. This would be a band-aid and I'd equate that more with rice than the sound....

Technically, the only possible benefit would be to actually vent warm air out of the system rather than to recirculate it. It will lose some heat when the air decompresses, but since the turbo's compressor efficiency will not be 100% it will be a bit hotter than it was when it first entered the system. However, the gains are marginal.

As far as differences, there are differences. Most notably, is adjustability. Most non-adjustables will be set to pretty safe levels, and do it's job well. But with adjustable units, you can tighten it up to retain some level of boost in the system which can assist in initial response when opening the throttle again. However, this can easily put you in the area of surge on a compressor map and damage your turbo over time. It's recommended that doing something like this is only done on ball bearing turbos as they can handle higher thrust loads than conventional bearings. Other differences are in how quickly they respond and how much they can flow. And these two traits can be hard to mesh as bigger flowing units use larger valves which may not be as responsive. Sequential BOV's are supposed to minimize this issue, but I do not have solid data to confirm if it is true or not. But they incorporate a small valve within a bigger one to combine quick response with large flow when needed.

[grimple1]

If exhausts can sound ricey... why can't bov's? touche!

you win.

[Chezedik]

So then if I am going low boost and don't need to be super high performance, super-expensive is not necessary? Or is that conclusion premature?

[C-Kwik]

So then if I am going low boost and don't need to be super high performance, super-expensive is not necessary? Or is that conclusion premature?

Well you certainly want a quality piece. What you don't need is one that is designed for high flow.

[Chezedik]

To ask a stupid question: What is the difference. I would think if it were OEM, then it will be of high quality (all DSM cracks aside). By cheap you mean the SSAC parts on ebay, or something like that, or do you mean OEM as well.

[get_up_mark]

What about OEMs versus aftermarket. I could get a 1g BOV for cheap, and if it will work just as well for my needs than I don't care. Do aftermarket valves seal any better?

i dont know if they seal any different but with my greddy type s my car would idle fine and stall apon revs. that valve cracked so now i have a 1g dsm valve and it wont even idle atmospheric i had to recirculate it. but its fine recirculated just a little quiet. i have a nice recirculations setup im gonna post pictures of sometime soon. everyone will like it.

[rn240sx]

I ran mine atmospheric for a while cause i liked the bov sound. I ran it this way without an afc and i had to blip the gas pedal when the rpm's dropped to about 1000 rpm or it would stall out, EVERY TIME..!!!I then got the afc and tunned in the dec-air feature and it worked great but i would have stall problems every once in a while, so it was not a perfect fix.. AND my idle was a bit lumpy cause the dec-air feature controls fuel at idle, which is what keeps ur motor from stalling when the rpm's drop.. It would read like 16-17 on the wideband at idle..The bad to atmospheric is that during shifts, u would have to build that boost pressure back up. Cause when u shift, ur releasing all that pressure....

I then went recirculated and i havent had a stall issue at all.. And during shifts, i dont loose any of the boost pressure, so when i hit the gas pedal, boost was there instantly. Only bad thing is, the PSHH can barely be heard... If u listen for it, its there, but otherwise, u cant hear it. And my idle a/f sits at 14.7 solid.. where it should be.

Hope that helps..

[C-Kwik]

i dont know if they seal any different but with my greddy type s my car would idle fine and stall apon revs. that valve cracked so now i have a 1g dsm valve and it wont even idle atmospheric i had to recirculate it. but its fine recirculated just a little quiet. i have a nice recirculations setup im gonna post pictures of sometime soon. everyone will like it.

I can't say for certain about the DSM valves, but some valves (I would suspect many OEM ones) actually are open when driving off-boost. This is to help reduce restriction and allow a more direct path for some of the air to divert around the turbo increasing gas mileage and response slightly. As boost is realized the valve shuts then opens when it sees the pressure differential required to open it again for an actual blow-off. It's possible the DSM valve you used may do this which could cause the symptoms you describe.

[C-Kwik]

To ask a stupid question: What is the difference. I would think if it were OEM, then it will be of high quality (all DSM cracks aside). By cheap you mean the SSAC parts on ebay, or something like that, or do you mean OEM as well.

It's hard for me to be as specific. I haven't used or experienced all the BOV's that are out there myself. I would try and get a general consensus through research to find out at least which ones to avoid.

[gtune4]

If exhausts can sound ricey... why can't bov's? touche!

you all and me drive rice bred cars, japan! ricer is just rice in bad taste!

both can sound cool if done right.

recirc also does not add any boost leak areas or whatever if you have your ride setup right. get better clamps if you have that prob!

i run mine both ways, change from time to time. i have noticed that the turb stays spooled up better on recirc and allows for better speed when up shifting. more power is waiting for you then!

[Jookmasta]

well seeing as i build full boost within a 500 rpm increment, power is always waiting for me during, before, and after shifting lol. as stated earlier, run it whichever way gives u the best driveablity results. btw, i use a greddy type s (authentic, not ebay knockoff) and have had zero issues.

[onosqv]

well seeing as i build full boost within a 500 rpm increment, power is always waiting for me during, before, and after shifting lol. as stated earlier, run it whichever way gives u the best driveablity results. btw, i use a greddy type s (authentic, not ebay knockoff) and have had zero issues.

The Greddy Type S on eBay are knockoffs? Is there a way to tell?