About Blow Off Valves
 

What is the purpose of re-routing the blowoff valve back to the intake stream and exactly where in the intake does it route back to? Where would the air go if it just goes back to the intake? Is this better than blowing it into the atmosphere?

Thanks.

Yes I'm gonna buy Maximum Boost one of these days. tongue.gif

From what I know it reroutes back to the air intake just right before the turbo. Whether there are benefits of that over venting to the atmosphere? I don't know. But venting to the atmosphere sounds cooler.....

If you're venting in the atmosphere on a MAF car, you end up with less air than what the ECU expected, since you just thrown it out, resulting in a rich mixture; if you re-route the air in the system, then the amount of air will be the same, thus preventing problems of running rich when changing gears or declutching.

It's also a lot quieter... Which may not appeal to the *ricer* inside you wink but is good for a TRUE sleeper.

You know... A sleeper that still has the 15* wheels? And has no stickers on the outside? And faded paint on the spoiler? And is a 1st gen Rev A that's dark purple?

Oh wait wink

That's what I'm going for. I just don't understand the concept of re-routing the air into a circle. Like how does it decompress the intake chamber if it just routes it in a circle? :confused: If you route it before the turbo, wouldn't it escape out the fiter? If you route it after the turbo, how will it vent or decompress at all?

You reroute before the turbo--but you have to figure that the turbo does have momentum, it doesn't change speed immediately so at any given instant suck in at least 98% of the air it was using just an instant before. Considering that you are still drawing some air into the engine you will be blowing off maybe up to 80-90% of the flow. As long as your BOV isn't oversized the intake tube will lose vacuum but wouldn't be flowing backwards. If the BOV is huge in a recirculating setup I guess you could cause some problems.

So size DOES matter?!? eek!

So I shouldn't get a BOV that is for 10-20psi if I'm only going to run 5-7?

If you have a Haltech, or something similar, couldnt you just tune it so the car runs leaner when it sees the throtttle is closed, thereby allowing you to have the nice BOV sound?

And red, you and your car are really insane, you know that right. :D I like it. Looks normal, but with 300whp+ on tap all the time. droooooooooooooool

Makes me think of this eclipse back home though. He has a BOV that vents to the atmosphere. When i hear it, part of me thinks *Damn, thats pretty* and another part of me goes *Yeah, but he's gotta be screwing up his drivability/chances of getting a race.*

Being an engineering major means i think too much. smile.gif

A blowoff valve that is strong enough to hold a 20psi charge is NOT going to open correctly on a 5-7psi setup -- or vice-versa. Yes, they are adjustable, but the range of adjustability really isn't THAT great. Certain blowoff valves do better under certain circumstances.

Just as someone described earlier, a recirculating blowoff valve isn't going to cause any problems, it's only there for problems that surround Karman or MAF sensors.

On a Haltech, there's no use for a recirculating blowoff valve UNLESS you just want it to be quiet smile.gif

Recirculated blowoff valves sound wierd.. Instead of a PEEEESSSHHHTT, it makes a *ffwhump* instead :D

<div class='quotetop'>QUOTE</div><div class='quotemain'>skierd:
If you have a Haltech, or something similar, couldnt you just tune it so the car runs leaner when it sees the throtttle is closed, thereby allowing you to have the nice BOV sound?</div>Mmm, not really. The air flow being read depends on how fast the compressor was spinning before you let off the throttle--if you're venting externally, the relationship between air & fuel is broken and can't be predicted. Think about this: if you're running the throttle at 100% open and snap the throttle closed, then compensate for that condition, you're changing the reading based on a huge air flow that is being dumped. So now if you were to go from 10% to closed, the air flow would be tiny, almost nothing would be dumped, you'd run way lean, detonation, boom. On the other end, if you calibrate the change when going from 10% to closed, it wouldn't affect the 100-to-closed condition much at all, you'd run way rich, smoke & choke.