What are the pros and cons of recirculating BOV

[DawgMode]

What are the pros and cons of recirculating BOV than just leaving it atmospheric

[240_Keyy]

pros:Your car will not backfire and bog down slightly after shiftingyou will go through spark plugs MUCH less frequentlyall around better driving experienceless tendency to sputter and backfire when coming down to a stop

cons:you don't get the mad tight soundyour mad JDM tightness lessenssure to not get the fly honeys

[SoCalS14]

^^ What he said.

[Silvia007]

Unless..... you get a Greddy Type S, then you still get all the pro's and still get the JDM Tyte sounds and the honies.

Mines louder then a mofo and it's recirculated... not as loud as uncirculated but still loud.

[cheez80]

add another con:

if you ain't got a bov with an available recirc. adapter (like the blitz) you'll have to make one.

[240dreams]

better mpg

[tubakins]

yea but if you recirculate it, you blow hot air (regardless if bov is mounted on hot or cold pipe) back into the system, when the air the turbo is taking in is colder

[powerls]

I just got my s13, the guy had a TurboXS bypass valve on it. it sounded like crap and it made my car stall out and gave it a bad idle. I threw that junk out and put on a Turbosmart Dual Port BOV. It fixed everything. It allows me to VTA and recirc, so my car stays happy.

[DawgMode]

correct me if im wrong but doesnt the atmospheric BOV mess with the MAF sensor which causes it to stall???

[tubakins]

yep

[powerls]

yep but the Turbosmart Dual port uses a offset port for the recirc, so the recirc is the first side open and the last side to close. The BOV is also fully adjustable by hand, no tools or shims are needed. It solved all my problems and actually looks good too!

[Projex240]

the best way around the cons and still having the pros--go with a blow through setup, (putting your maf on the cold pipe) & no matter what people tell you, it doesnt hurt anything. I have NEVER seen one car doing it has had problems that could be contributed to the blow through. For those who dont know-heres how it effects you in both ways:

When you maf draws air through in a "draw through" setup(maf in standard place before the turbo) it meters it and tells the ecu how much fuel to compensate for. When the BOV is atmospheric, it lets all of the air out after the maf has already told the ecu to dump in x amount of fuel. SO the fuel is still there, but the air is not. You run rich, you foul out plugs, you backfire, stutter, and die at redlights. Its sucks. I dont know why people do it at all with a drawthrough. The s-afc's decel-air function is a band-aid, and a weak one at that. It still is not a perfect fix.The blow through puts the maf on the pipe just before the TB so when it meters air, it does so with air entering the motor, and not the turbo. SO if you blow off atmosphericly, it doesnt cause problems since the air is blown off BEFORE its metered by the MAF. I personally think its a win/win situation. I havent heard of anyone with negative drawbacks to it. If so, they blamed the maf when it was something else in the end.

I forgot to mention though one thing to ensure this works right. A maf is sensative to turbulence. When placing the maf on the cold pipe, make sure there is NO bends in the piping for at least 6 inches before the maf. This cuts out the turbulence, and ensures smooth flow through the maf.

Theres some food for thought.

-Josh

[Luke]

Don't forget, the blow-through setup won't work with the stock SR MAFS, it's just so tiny. If you use a FMIC kit like Greddy or Blitz, chances are your cold pipe is like 3" diameter. It's not going to be an easy as chopping part of the cold pipe off and hooking the MAFS up in there.

Most people won't even consider a blow-through setup without the Z32 MAFS to support it. Something for you guys with stock MAFS to keep in mind.
Modified by Luke at 3:16 PM 1/14/2005

[RMiller]

A little off topic, but I have something to say about the Type S and using 1 or 2 vacuum lines, as there are 2 nipples. One is the main nipple, the other is at an angle and I always assumed it was for breathing or something. I know the Type R has one also, maybe others as well.

Anyway, some people swear their car runs better with a line going to each. Do not do this, the bov will not open. I just did it to see what it would do and all I got was some crazy surge, nothing else. I just wanted to mention it because more than one person claims to do this. Plus the thread topic has pretty much been covered.

I'll add one thing: The absolute best way to get around the problem is to use a MAP setup. And I have heard of MAFs crapping out fast using blow-through, presumably because cold-side temps are higher than ambient temps. But that may only be true with the stock maf.