Really, the difference is that on some/most turbo cars... like mine or a wrx or evo... we use MAF sensors to let the ecu know how much air is going into the engine, and the ecu adds the right amout of fuel to match that reading... the problem with blowing off a bov into the atmosphere on a car with a MAF is that the MAF will read a certain amount of air and the ecu will pump out that much fuel for it... but once the bov opens, it releases all that air that the ecu calculated. And in return, you end up with more fuel than you do air (running rich). Recirculating the bov allows the air blown off by the bov to be shot back into the intake through a tube so that no air is lost and the air/fuel ratio going into the engine is as read by the MAF. As a result of blow off into the atmosphere on a car with a MAF, you'll run rich, backfire, some have very severe idling problems (stalling out from the engine getting flooded with fuel), and I've seens many cars actually bog at high rpms... for a while, on the freeway, if i would hold it at a certain psi that was'nt full boost, say 5psi, my car would choke really bad and jerk and feel like the engine is going to blow because of the engine being flooded by fuel. But civics use MAP sensor and not MAFs so you guys are lucky and dont have to recirculate. But anyways... recirculating = quiet, atmospheric blow off = loud... loud = cops. Hope this helps some... sorry if it's confusing.Shiznit said:whats the difference?
bov?
- Thread starter TiiM iiS l3eAsT
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how can u get in trouble for that?....and im not sure but arent turbos illegal in cars unless there for the track?
Its from a bov being set with too little spring tension so when you let off the throttle the vacuum causes the bov open too easily and too fast so the valve just bounces off of the top of the diaphram and just bounces instead of just staying open. Also depending on the configuration of the bov a weak tension setting can cause the bov to be pushed open by boost.PANGES said:
Compresser surge is caused by one of two things.
1. When you let off the throttle the turbo is still pumping out the same amount of psi it was before you let off the throttle. If the compressor charge isn't allowed to go somewhere it will hit the throttlebody and cause a violent surge to back up in the intake plumbing. This surge can destroy a compressor wheel because all of a sudden the compressor is hit with a very strong and turbulent air charge and its like dipping a compressor wheel into water while its spinning 100k+ rpm.
2. The second cause of compresor surge is by having a turbo that will pump out more compressed air than the engine can swallow. This pile up of compressed air from the engine not being able to ingest it fast enough can create tremendous amounts of turbulence which can destroy a compressor wheel as well.
Its just the bov not working to its full potential but it won't destroy anything. If you have a violent enough compressor surge to destroy the compressor wheel then you either seriously f**ked up with your compressor mapping, were running a ton of boost with a stock recirc system, had a bov failure, or a combination of any of those.c_diddy said:
when I posted these vids I was told that I had compressor surge. I just always thought that was the way my bov was supposed to sound 
vids
http://media.putfile.com/doughnuts22
http://media.putfile.com/doughnuts_2
vids
http://media.putfile.com/doughnuts22
http://media.putfile.com/doughnuts_2
I always thought that it was because the bov was'nt opening at all or the piping was too small, causing the pressure to shoot back into the turbo and I thought the sound was just from the air being "sliced" around from it trying to go in 2 different directions... lol. You way makes more sense.... but how does it work for people that get compressor surge when they have no bov?Revolver said:
Cars running low psi ~7 on a small turbo T25 K03 w/e don't have enough of a high velocity air charge to create any kind of violent compressor surge. Usually a car with no bov and low psi on a small turbo will just kind of surge a little bit when you let of the throttle at full boost. My SAAB had a recirc system but it was very tiny and so when I would let off the throttle after a full throttle run the engine would surge a couple of times very quickly. It felt about the same at tapping the throttle 2 or 3 times at higher rpms in an NA car and it was not violent enough to be concerned with.PANGES said: