Blow off valve atmosphere vs recirculation?

Post by **SpeedRacer1** » Sun Sep 08, 2002 11:14 pm

I was wondering if the recirulation kits for BOV's only do any real good at idle or are they good across the board. I was looking at the Blitz and HKS Bov's and I noticed that they are supposedly closed at idle. If they are closed at idle wouldnt that mean I can get an atmospheric Bov and not worry about side effects of the MAFS?

What does the atmospheric bov effect on a mafs controlled car?

(Im really too tired to think of the physics/mechanics of it) *also who had the bright idea of only letting us search with 4 or more letters, I already tried to search BOV but that appearantly doesnt work.

Post by **Daunttless** » Sun Sep 08, 2002 11:14 pm

A MAFs equiped car will have issues on hard shifts because the air will have already been metered, and then it doesn't show up in the engine. However, no one told the ECU it wasn't there so you'll run rich for a split second after shifting causing jerking and stumbling.

Post by **Nismo_Freak** » Sun Sep 08, 2002 11:14 pm

Daunttless wrote:A MAFs equiped car will have issues on hard shifts because the air will have already been metered, and then it doesn't show up in the engine. However, no one told the ECU it wasn't there so you'll run rich for a split second after shifting causing jerking and stumbling.

Its a small studder, similar to a clutch engaging and when you are on the throttle which you have to be in order to boost the studder is hardly felt.

Post by **SpeedRacer1** » Sun Sep 08, 2002 11:14 pm

So what im gathering is that I can get an atmospheric BOV if it stays closed at idle.

Post by **Avram** » Sun Sep 08, 2002 11:14 pm

What about venting to atmosphere before the MAF? (running "blow-through" ?)

Post by **SpeedRacer1** » Sun Sep 08, 2002 11:14 pm

Yikes...

Post by **Sintax** » Sun Sep 08, 2002 11:14 pm

Quote »Avram: What about venting to atmosphere before the MAF? (running "blow-through" ?) [/quote]

actually it does work, and i've seen one or two cars here in the US that are running in a blow-through method. It tends to be more popular in Japan and Au. i've seen it discussed on a few other boards recently.

here:http://forums.freshalloy.com/ubbthreads ... o=&fpart=1

and here:http://forums.freshalloy.com/ubbthreads ... o=&fpart=1

hope this may clear a few things up.

-scott

Post by **Movingviolation240** » Sun Sep 08, 2002 11:14 pm

I second the blow through MAF, I just did mine on sunday, and it makes a big difference in drivibility. Some people told me it wouldn't work, or that it would be a waste but trust me, it feels MUCH nicer off boost now. Having the MAF 5in from the TB as opposed to 5ft and an intercooler really makes a difference in throttle response and smoothness.

Useually if you keep the BOV 'tight' you won't have problems with stumbling, or if you have somthing like the Emanage, just take it really lean bellow 1,000rpm and it won't stall when shifting (normally).

I know a guy who dose a chip, that also would get rid of the problem.

later,

PaulOrlando, FL

Post by **Mlaurie69** » Sun Sep 08, 2002 11:14 pm

Cool...that is good information and it makes perfect since......So I would move the MAFS over to the Throtle Body side, just after the BOV.

Another bonus here is I can still have the nice Wossh sound of the BOV dumping pressure to the Atmosphere.

Post by **neergnevets** » Sun Sep 08, 2002 11:14 pm

yeh plumb back bov's are a great. Had the apex'i bov on my sr20det for a while, bloody terrible. Like the other blokes said, makes the car run rich and if you have a 85mm exhaust, a little back-firing. Sold it and bought a turbosmart plumb back and had change to spare.

You guys do know that the sr20det runs a std internal bov right, that you take out!!!

Post by **Movingviolation240** » Sun Sep 08, 2002 11:14 pm

neergnevets wrote:You guys do know that the sr20det runs a std internal bov right, that you take out!!!

Nobody (well allmost nobody) here runs the stock BOV since it's part of the intercooler settup, and when people over here do the swap they just start out with a big intercooler.

Post by **bwalker240** » Sun Sep 08, 2002 11:14 pm

Movingviolation240 wrote:Nobody (well allmost nobody) here runs the stock BOV since it's part of the intercooler settup, and when people over here do the swap they just start out with a big intercooler.

I'm running the stock IC and BOV in my 98 S14 (haven't turned up the boost yet).

For those of you running front mount IC, do you ever take the car to the track (not drag or autocross - track events like time trials). Any problems with cooling because of the IC?

Post by **ITR_KILLR** » Sun Sep 08, 2002 11:14 pm

I've got a 95 200, could I run my MAF before the TB too?

Post by **neergnevets** » Sun Sep 08, 2002 11:14 pm

was the s14 body sold in the US? does it look the same the japanese s14? What are one of those worth? ballpark figures? Sorry i relise im getting off the topic but its exciting to see that the USA has a silvia community!!!!! Fair dinkum

Post by **SpeedRacer1** » Sun Sep 08, 2002 11:14 pm

Yes we recieved the S14 with both the rounded headlights and the angled headlights. So overall we recieved both the S13 and S14, all with KA24(D)E engines and no SR's. There were no SR20DET's sold in North America to my knowledge and that is why they are so expensive. An S14 here will be about $4000 to $10000 US dollars depending on location and quality.

Blow off valve atmosphere vs recirculation?

Blow off valve atmosphere vs recirculation?

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