Stock BOV fluttering at altitude?
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Stock BOV fluttering at altitude?
I just brought my car from sea level to ~9,000ft and suffice to say, the car is driving much differently. I haven't been able to re-tune yet since my Tactrix cable needs to be re-serialized, so I've been going pretty easy on the car. One thing I have noticed, though, is that I get a really nasty flutter noise every time I let off the throttle (except for 5psi and above). The only time I would get this back home would be if I was in 5th gear going up a small hill, didn't have enough speed, and let off to down shift. Now I assume this is just because of the high altitude, but I wanted to make sure. It sounds exactly like this.
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Your getting what is called flutter dump. Check here for info:
I must correct myself FLUTTER DUMP IS A FORM OF COMPRESSOR SURGE.
Here's a couple links which do a great job demonstrating what's going on with your DV:
This is what compressor surge sounds like:
http://videos.streetfire.net/video/T...sor_163406.htm
It wont be as loud on our smaller turbos, but it is still pretty noticeable...
Here's a vid on the flutter dump:
http://videos.streetfire.net/video/W...ump_151792.htm
This one shows the delay of the BOV, causing a surging.
http://videos.streetfire.net/video/S...BOV_105407.htm
And for those of you interested since you have X's:
http://videos.streetfire.net/video/E...low_163389.htm
And no I am not affiliated with synapse in any way, nor do I own one of their products....yet lol.
Here's a couple links which do a great job demonstrating what's going on with your DV:
This is what compressor surge sounds like:
http://videos.streetfire.net/video/T...sor_163406.htm
It wont be as loud on our smaller turbos, but it is still pretty noticeable...
Here's a vid on the flutter dump:
http://videos.streetfire.net/video/W...ump_151792.htm
This one shows the delay of the BOV, causing a surging.
http://videos.streetfire.net/video/S...BOV_105407.htm
And for those of you interested since you have X's:
http://videos.streetfire.net/video/E...low_163389.htm
And no I am not affiliated with synapse in any way, nor do I own one of their products....yet lol.
Yes...completely let off the gas pedal.
The surge you're experiencing is very mild, normal, and repeatable every time. Like I said in an earlier post, when you're at part throttle and you let off the gas pedal to a lesser part throttle, there's not enough vacuum in the intake manifold to open the BOV. When the BOV doesn't open and the throttle plate is blocking the airflow from the turbo, you get compressor surge. Part throttle surge with little/no load on the engine happens on almost every turbo car and is not something to worry about.
What you don't want at all is surge at WOT or to not have the BOV open at all.
The surge you're experiencing is very mild, normal, and repeatable every time. Like I said in an earlier post, when you're at part throttle and you let off the gas pedal to a lesser part throttle, there's not enough vacuum in the intake manifold to open the BOV. When the BOV doesn't open and the throttle plate is blocking the airflow from the turbo, you get compressor surge. Part throttle surge with little/no load on the engine happens on almost every turbo car and is not something to worry about.
What you don't want at all is surge at WOT or to not have the BOV open at all.
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ksattic
Evo X General
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Feb 24, 2009 08:19 AM
altitude, bov, cars, compressor, dump, evo, flutter, gas, high, higher, pedalflutter, surge, turbo, turbocharged
