Can someone explain to me why a BOV is bad for a UrS4?
09-02-2006, 07:11 AM
#1
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Can someone explain to me why a BOV is bad for a UrS4?
I'm not sure I get it. We have all these stupid problems with our BPV's... why does dumping the air hurt anything? It should have zero effect on the system under acceleration.
09-02-2006, 08:02 AM
#5
We have a Bypass Valve (i.e. 710N). It keeps the turbo spooled during shifting as per the diagram...
<center><img src="http://pictureposter.audiworld.com/52091/aanairflowdiag.jpg"></center><p>inside (here). If the boost is just dumped during shifting (when your foot is off the throttle) there is more possibility of the turbo stalling and then having to be brought back up to speed. It may sound "kewl" but for a street car, BOVs are not an efficient way to go.
But the "rice" boys love them. ;>
Diagram is the one I posted earlier, with Sean D.'s annotations.
But the "rice" boys love them. ;>
Diagram is the one I posted earlier, with Sean D.'s annotations.
09-02-2006, 08:20 AM
#6
Just curious how you came up with that???
If the BOV vents the turbo charge air to atmosphere and completely unloads the turbo, how will the turbo have a higher possibility of stalling? Since I have an AEM stand alone EMS, I do run a BOV and have experienced no evidence of turbo stall during shifts. I do not like the sound but I have found that the volume is less than my old TurboXS BPV run with an open filter element intake. What really makes a lot of noise is the mushroom air filter mounted at the turbo inlet. When mildly accelerating on the street, I have seen pedestrians jump back as I approach from the intake noise.
Hap, wit dakine BOV observations not from Evahboost, Maguire
Hap, wit dakine BOV observations not from Evahboost, Maguire
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09-02-2006, 08:49 AM
#8
Pg. 32 of the VAG Self Study Programme No. 111 (see inside)
<center><img src="http://pictureposter.audiworld.com/15624/bpvfunction.jpg"></center><p>I didn't say the only way a turbo can work is if it has a BPV and not a BOV. I said a BPV is more efficient for a street car. By "street car" I meant one designed to be used by normal people during typical driving.
I think your car is more of streetable race car than "street car". As a result, a whole different set of rules apply.
You will no doubt disagree.
I think your car is more of streetable race car than "street car". As a result, a whole different set of rules apply.
You will no doubt disagree.
09-02-2006, 08:51 AM
#9
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When is the BPV open?
it is open when the throttle is lifted while under boost, which allows metered air (air that is accounted for by the MAF) to escape out of the closed system, which will cause the car to run rich for that second or two. BUT, correct me if i'm wrong, the BPV is also open when under full vacuum, such as idle or low throttle cruising. If a BOV is also open at this time, it is like the car has a huge vacuum leak. Am i wrong?
09-02-2006, 08:55 AM
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that is when audi first started using the BPV, when no one was using a bov or bpv
such as in the old 5000s, Coupe Quattros and such, where they had no way of relieving the pressure when the driver let off the gas while under boost. That is why many 5000t owners who mod their cars add a bpv. Audi came out with the bpv here in the 3B motors in the '91 200tq i believe.