legacycentral bbs

It's pretty common talk here that we would all like to run atmospheric every once in a while. What can we say? We are men (and woman) and things that make noise like that are ego strokers.

Well, one of my projects for this weekend is a DIY Atmospheric BOV that won't make you run rich (well, it will, but not all the time. I'll explain later).

The idea is simple.

Automatic sprinkler valve on a T off of the DV return line. Set this up to a momentary switch that is only opened at WOT (pedal to the metal). Closed all other times.

When the switch is open (only at WOT), the DV vents to the atmosphere. When the switch is closed (not WOT), the DV recirc's as normal.

In theory, this shouldn't pose much of a problem, and since the DV line is not entirely closed off, some air still bypasses back into the intake. You would only run rich for a fraction of a second.

The lag time of the sprinkler valve would allow the valve to be open for a few tenths after you let off the gas. Fully allowing the excess backpressure to vent off.

In my own testing last weekend, while doing a 2nd gear WOT pull and open atmosphere, I had zero issues with richness, it was only when I was stopped and revved.

With my method, as long as you aren't WOT the valve is closed and the car acts normally. It will work as long as you know what will and will not happen.

As history dictates, I will be giving the mod the title: The BAC BOV mod.

I will be heading out to Home Depot today to price some stuff out.

What do you guys think of my idea?

But the DV is always closed at WOT, innit?

Why not just use a check valve as others have done?

My bad, I mean that at WOT, the valve will be open which will let the DV dump to the atmosphere.

A check valve would always be open under any condition (when the DV dumps), wouldn't it? This would only be open at WOT, so it wouldn't affect normal driving in the least. I've also not heard of the check-valve idea, any more info?

What I'm saying is that at wide open throttle you never want to vent. Ever.

The two situations you want to differentiate between are 1) The throttle is closed but the turbo's spinning and 2) The throttle is closed (or mostly closed) but the turbo's not really spinning.

Under situation 1, you want to vent the pressure. Under situation 2, you don't want to vent because you'll actually end up sucking air in.

A check valve set up to only allow air to flow out of the DV and never into it would be open under situation 1 and closed under situation 2. You can try doing a search for "check valve" or something to find the other thread(s) where it was discussed.

I haven't tried this setup, but you should be aware that there is the possibility for this setup to still muck with your fuel trims, since during the short time that pressure is being vented you the ECU will see weird feedback from the lambda sensor.

Hmm, I see your point. Didn't even think about it sucking air back in.

Oh well, back to the drawing board.

A check valve in line with the DV is a good band-aid to cover up screwy MAF sensor readings, but it seems like a waste of money (even if you get them cheap) for something that won't be beneficial at all. IMO, I don't see the fascination with the bov sound. I liked the fact that people DIDN'T know I was turboed. But to each his/her own.

While being a sleeper is cool, it would be nice every once in a while if you could turn a head or two.

Why not just mount a speaker under the hood and make a circuit to make a BOV sound whenever you slam the throttle shut then?

Adds to much weight, and it's a little TO ricer for my taste, lol.

I dunno... I think it might actually be less ricey, since your engine would run better.

hahaha true, and it wouldnt be that heavy, what kind of speaker are you thinking? Just use one of your stock ones if you've replaced them I think the bov sound is fun every once in a while. But it seems like a waste of money to me

THAWA wrote:what kind of speaker are you thinking?

I dunno. What kind of speakers do PA systems use?

But it seems like a waste of money to me :)

Effort, too.

I had a PA system in my old wagon that could make animal noises and sirens. Also had a mic you could put in a speaker or yell into to tell parents to get their drunk, puking kids off their lawn when dropping them off from a party at 3AM. The PA speaker was very light.

Steve

I thought this would be a perfect time to throw this video link in.

http://spoon.org/stuff/Video/AntiRicer.wmv

Haha, I was just trying to find a way to vent to the atmosphere with minimal impact on performance. Like I said, it's nice to turn a head or two sometimes.

A stock speaker is plenty loud, but like boostjunkie said checkvalve. I think grant did this, and mtk aswell. But my memory is sketchy right now and I dont want to search for the topic.

I don't think a normal car audio speaker would be so loud without a proper resonating chamber.

true

BAC5.2 wrote:Haha, I was just trying to find a way to vent to the atmosphere with minimal impact on performance. Like I said, it's nice to turn a head or two sometimes.

Then you would probaby be better off running a dedicated atmo bov (50-50 even) rather than the stocker. Although your car will run rich, the design of the bov would prolly keept idle a litte more steady than the stocker.

Don't mind me, I'm just thinking out loud.

Nah, not really worth it to me at this point. It was just a passing idea.

I don't understand why you'd want to put a check valve on the BOV outlet...

Why wouldn't you just put a check valve on the vacuum hose that goes to the BOV? That way you don't need to buy an enormous check valve which will make your BOV much quieter and funny sounding, and you'll get exactly the same effect. The BOV can't open under vacuum if it can't see any vacuum to begin with...

Thereby making the stock BOV non-functional..

MK

What MK said.

See my earlier post about the two situations. You need the valve to open when the pressure drop across the throttle body is very high.

What about one of Turbosmart's dual port BOV's? Routes 40% of the air back into the intake and 60% to the atmosphere.

Aw hell, why not just a whistle inline with the BOV recirc plumbing, lol.

Haha, whoops. For some reason I was thinking manifold pressure spikes caused the BOV to open...