# do you know your blowoff valve sounds? **URL:** \ **Category:** SON240sx Automotive\ **Created:** [December 16, 2009, 2:42pm UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278 "2009-12-16T14:42:24Z")\ **Posts on this page:** 10\ **Page:** 3
**Author:** ![Keez](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/keez/32/5570_2.png) [@Keez](https://forums.speedlife.net/u/Keez)\ **Post date:** [December 17, 2009, 11:04pm UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/41 "2009-12-17T23:04:08Z")
i ran no bov on my t28 on 0.5 bar forever…when i started hitting 1 bar is when i decided to put a blow off valve on. ---
**Author:** ![izzo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/izzo/32/5769_2.png) [@izzo](https://forums.speedlife.net/u/izzo)\ **Post date:** [December 18, 2009, 7:57am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/42 "2009-12-18T07:57:26Z")
7 psi and no blow off?? man imo bov is a must in turbo car. gotta love that psshing sound 😃 ---
**Author:** ![Hacknik](https://avatars.discourse-cdn.com/v4/letter/h/ba9def/32.png) [@Hacknik](https://forums.speedlife.net/u/Hacknik)\ **Post date:** [December 19, 2009, 8:55am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/43 "2009-12-19T08:55:56Z")
Lol, since when is Compressor Surge cool? ---
**Author:** ![John\_sinopoli](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@John\_sinopoli](https://forums.speedlife.net/u/John_sinopoli)\ **Post date:** [December 19, 2009, 8:57am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/44 "2009-12-19T08:57:39Z")
tial ---
**Author:** ![cailesj](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cailesj](https://forums.speedlife.net/u/cailesj)\ **Post date:** [December 19, 2009, 9:23am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/45 "2009-12-19T09:23:30Z")
> [@so my window got smashed in](https://forums.speedlife.net/t/so-my-window-got-smashed-in/25291/54): > > Does he have a duck whistle on that car? I’d so rock that, quack on every shift 😃 I did that for about 2 weeks, it gets old fast, funny for a bit though ---
**Author:** ![XenoVibe](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/xenovibe/32/5739_2.png) [@XenoVibe](https://forums.speedlife.net/u/XenoVibe)\ **Post date:** [December 19, 2009, 10:20am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/46 "2009-12-19T10:20:43Z")
I like the one that sounds like stewie shivering… LOL ---
**Author:** ![Tarz](https://avatars.discourse-cdn.com/v4/letter/t/43a26b/32.png) [@Tarz](https://forums.speedlife.net/u/Tarz)\ **Post date:** [December 19, 2009, 11:27am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/47 "2009-12-19T11:27:33Z")
i could be wrong but isnt the cha cha chaaa bad for the turbo?? ---
**Author:** ![nd4boost](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nd4boost/32/5627_2.png) [@nd4boost](https://forums.speedlife.net/u/nd4boost)\ **Post date:** [December 19, 2009, 12:10pm UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/48 "2009-12-19T12:10:01Z")
yes in the case of compressor serge, that would be the sound of compressed air smashing back into the turbo, BB turbos handle this action much better tho ---
**Author:** ![ARC240](https://avatars.discourse-cdn.com/v4/letter/a/d26b3c/32.png) [@ARC240](https://forums.speedlife.net/u/ARC240)\ **Post date:** [December 21, 2009, 7:07am UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/49 "2009-12-21T07:07:24Z")
Yup, that sound is flutter. Results from excess boost pressure being deflected back towards the compressor turbine (when you snap the throttle plate shut) and forcing it against the blades of the turbine wheel. The air passing through the turbine is what makes that fluttering noise as that is it’s easiest route of escape. It wont really harm anything at low boost (~5psi or below on stock turbo as they use ceramic turbine wheels/blades and cannot take that type of stress, if you repeatedly flutter at higher boost as it begins to chip away at the ceramic blade, causing it to become more brittle). The max could be more, but I say fairly SAFE flutter level is anything under 5psi. What someone has said about ball bearing turbochargers coping with flutter more easily is true, ball bearings are better load-carriers for the most part that can cope better with both radial and thrust loads that are put on the impeller shaft (what the turbine wheels are connected to) than standard journal bearings. Cars running no BOV or have one, but the spring is set too tight experience flutter. Your stock ECU is set to calculate for some sort of recirculation from the stock BOV, if you take away that recirculated air, you might experience stalling at a low RPM when coming to a stop/taking your foot off of the throttle, so I’d avoid blocking anything. Generally, its more safe to do without any flutter, but up to you really. Wastegates can do this too, but the flutter is MUCH more rapid and is caused by something different. Real compressor surge, however, is more commonly experienced while under both load and boost, most commonly caused by either a mismatched turbo (undersized) or overspeeding, where in either scenario, the turbo is exceeding it’s safe boost limits at that given turbine RPM. This usually causes a bumping or a loud, intermittent “chirp” while under load. A true case of surge isn’t only deadly to the turbo, but the engine as well. Hope that helps and clears some stuff up. ---
**Author:** ![Prometeus](https://avatars.discourse-cdn.com/v4/letter/p/b38774/32.png) [@Prometeus](https://forums.speedlife.net/u/Prometeus)\ **Post date:** [February 18, 2010, 10:35pm UTC](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278/50 "2010-02-18T22:35:19Z")
Ya ARC240 is right the cha cha is good for 1 thing dancing, surge is not good. Even if it dose not cause damage its extra stress on your turbo, also it effects spool-up time as the turbine has to spin up after its been slowed or stopped by reverse flow. BOV was meant too avoid that by allowing air to escape through it to atmosphere or recirculated back, this allows turbine to keep spinning freely and dose not need to be spun up form nothing if it dose in fact slow down that much. That at least is the theory behind it. How much it actually slow down i don’t know but i have read that severe surge could actually reverse the spin of the turbine if that’s true then the turbine is taking hell of a lot more workout than it needs to. [Previous page](https://forums.speedlife.net/t/do-you-know-your-blowoff-valve-sounds/130278.md?page=2)