So I have a Rec BOV that I installed a wile back and its been running great since but I just tested 2 different spring types to see if I could get less flutter out of the turbo.
With a softer spring I get less flutter I also get less power out of the turbo. When I place in the hardest spring the turbo will knock you back in your seat. but will flutter like mad. There is no PUSHHHH… sound at all. If there is i cant hear it over the flutter. The sound 100% comes from the cone filter.
I am running 6 PSI on a T28 turbo ka24de. Does anyone with a stock SR get flutter on boost? maybe I ran the BOV too close to the compressor as its located on the hot pipe?
If you close off the bov totally, or have a spring that’s too heavy, no air comes out of the bov and it makes flutter. The sound is made by the air pressure ‘bouncing’ between your turbo and air filter. It doesn’t hurt the turbo or engine at all, and it sounds pretty cool, but it tends to slow down the turbo between shifts so it has to spool back up to make big boost
I took out the bov on my skyline in the summer for a bit, just for the fluttering… But went back to the recirc cause losing boost was annoying
Get and hks ssqv I’m running vented out with no tune and it runz great and only get a little flutter if Im letting go at low rpm but if I give it it all comes out the bov with a very loud sound abd no surge
[QUOTE=SlidingSideways;3436225]If you close off the bov totally, or have a spring that’s too heavy, no air comes out of the bov and it makes flutter. The sound is made by the air pressure ‘bouncing’ between your turbo and air filter. It doesn’t hurt the turbo or engine at all, and it sounds pretty cool, but it tends to slow down the turbo between shifts so it has to spool back up to make big boost
^^^ you should know what your talking about before spreading false info!! It’s not air pressure bouncing back and forth between the turbo and air filter. It’s called “compressor surge” which is the air having no where to go but back through the turbo causing it to spin backwards when the throttle is closed suddenly. This will harm your turbo. Stock sr’s have the recirc valves on the hot pipe, that is not your issue. Make sure your vacuum lines are setup correctly!!
yeah the vacuum lines are not the problem. But the other side of the coin is if I’m not getting the same power out of the turbo i was before this also tells me the BOV spring is too weak to stay closed on boost. so it really feels like there is no way to win. almost sounds like i need an electronic BOV to keep the plunger closed on boost but open enough to not cause flutter it also then has to close fast enough to keep the RPM up. only thing i can think of that can do that is an electronic BOV and i have only ever seen them on P2 cars. I’m sure they also cost about as much as my whole car.
the only thing i can think of that may help is maybe a wider vacuum tube to allow more flow. What i need is more vacuum pressure from the engine it seems that -25-30 psi is not enough. The BOV is about 3/4-1" inch in diameter so it should be large enough to do the job.
your bov doesn’t have an adjustable spring? :\
I get flutter up to like 2-3k rpm and then after that it does the PUSHH sound. (sr20)
Do you mean on throttle or immediately off throttle?
decelerating i make -28-30 idle is -23. when I get the turbo to spool up and get 6PSI and immediately off the throttle it will give me a strong flutter.
no i have no screw but I do have shims and 3 different springs to be honest the screw isn’t the problem. its like I need a stronger vacuum to pull the BOV open even more. and to be able to run a heaver spring.
see mines the opposite of yours i have no sound at all at 2-3 k (on the soft spring) then when i push it and get 6 psi it will flutter. when i use the heavy spring it will flutter at 2 k and up. but that turbo becomes real fun with the heavy spring.
any other help would be great. This is my first turbo and KAs don’t come stock with one so I’m learning as I go.
then get a new BOV from the sound of it your current one is pooched! my old one didnt close when it was super cold cause the spring got stiff, and for the comment earlier HKS models are not adjustable only the first two generations were…
find a friend with a simular model and switch up and see what happens!
It is new. and its the second one I’m on and the old one did the same thing but was atmospheric. it was much worse. This one I have had the best results with less flutter. The bov operates as it should it just its not working hard enough. I will try a few small mods to this BOV then I will look into a electronic one if that doesn’t work, or electronic vacuum. at least that will do what its suppose to regardless of other factors.
This topic has been beaten to death by every 240 forum in the world. There is no evidence supporting compressor surge being “bad” for the turbo, or one self-destructing because of it. Manufacturers don’t like weird noises coming from the intake system so they fitted SRs with factory recirculation valves. CA18’s never even had one. A post above said the recirc system on a stock SR is on the hotside, for S14 SRs it is located on the cold side. Only drawback besides the noise of fluttering is the slight hesitation to build up boost again between shifts. As for the compressor wheel spinning backwards that just doesn’t happen. For drifting, running with no bov is the recommended setup by Power By Max. OP, do whatever you want with your car, you’re not hurting it, especially at stock boost lol. I prefer to recirculate a bov with a tight spring, best driveability imo.
I came to the conclusion last night that the BOV is working correctly as i said but with the soft spring it was fully open all times. it was just simply not moving enough air at its full open position. so I modified the bov and switched to the tightest spring and one shim and have much better performance out of the BOV and turbo. still have some flutter but its quieting down. tomorrow I will open the release hole up even more to allow more air to pass through and that should hopefully solve this.
I hear from many that flutter wont hurt it i hear from others it will, never seen solid tests that prove either way. This is a DD car and I am trying to make it run as if it was designed for a turbo from a factory. But that said with a 9.5-1 compression ratio in a 2.4L with 6PSI boost. this thing will give SRs a run for their money.
You are trying to fix something that isn’t broken, and you’ll end up with a car that doesn’t work as good. I don’t know what your goal is but you can’t vent 100% of pressure through the bov, it’s physically impossible. All bov’s leak anyway so just recirculate and start using that metered air instead of wasting it, it WILL make your car run better guaranteed.
the way the bov was working before i may has well stuck a tube straight from the hot pipe to the intake. it was venting about 80% all of the time and took a lot of gas to get the turbo to spool and build pressure. It runs better now.
this bov is open at idle about enough to stick a pencil between the plunger and the hole its suppose to closed over. So if i start the car as a test with it vented to the outside to watch the plunger the car almost wont start and the revs go up and down. BOVs do leak im aware of that but i dont “think” they are suppose to leak that much air. either way its more closed now then it was before and runs much better. when all buttoned up I get the pull i did from the tight spring and less flutter. I am simply trying to “reduce” the flutter so that I don’t damage the compressor if its possible or not.
Sounds like to me your bov is ment for high psi than your running. It’s fulltering because you build pressure it opens, turbos still spinging (throttle closed), pressure builds and it opens again. Your blow off should open with vacuum(and stay closed under boost) not only pressure in the pipe. Once there is vacuum, the setting on your spring determines how much air leaves. It sounds to me like you have too hard of spring so only a little air is getting out then it builds again flutters. My bov is adjustable by turning a hard or soft so it was easy to play aroud with it until it just popped once “pussh”. As others said at low rpm it flutters all day because I’m not at a high enough pressure to exhaust the system quickly. You should find your self a stock bov and see how it reacts, if it’s not right then you have vacuum problems.