can't get rid of flutter in greddy type s
can't get rid of flutter in greddy type s
like the title says. i've played with the adjustment screw and i've used both springs. at low rpms, the thing keeps fluttering when i get off the throttle. at high rpm's, the thing just whooshes. i don't get the greddy type s whistle, which is actually fine by me, but makes me think something's wrong. i have a k&n drop in and it was fine when i put it in for the first few days, now it's doing this. i noticed the hose connecting the back end to the upper IC pipe is pushing against the BOV a bit, but i checked the connections and it seems to be doing alright. i don't really want to cut the hose, but i might resort to doing that. anyone have any feedback for my current dilemma?
I had the greddy on my DSM & could never dial out the fluttering (compressor surge). I didn't know about the dual springs. I just got an HKS SSQBOV and it worked better, although it still had *slight* surge once in a while.
Good Luck
Good Luck
hmm... well, it would appear that i get the flutter at and under around 3500 rpm. i mean, i am/should be building boost around there, so i guess it's still a bad thing. also, how do i know/ how can i tell if my bov is being blown "wide open"?
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uhm... what is so bad about the fluttering? at least it's opening, cuz that's what would cause flutter... if you didn't hear anything you'd get a bucking which would be much less desireable. if you don't like that sound... get another valve... but you'll always get fluttering, even the stocker flutters.
like i said, do the single spring mod. my evo is stock, except for tt and bov, and mine has never fluttered with the single spring mod... NEVER. it doesnt leak, nothing. if ur not pushing boost over 21, then do the sine spring mod, get th adjustment just right and it will go away. the one reason my friends flutters is because he doesnt have the single spring mod, because hes got a bigger turbo pushing way more boost. my friend with a gsx doesnt even have the single spring mod and hes got a super 16g and his never flutters...
Hook up a pressure source to the lower nipple
You can totally elimiate that flutter if you source a line from a pressure source pre-thottle body.
You are fluttering because when you lift partial thottle of at a lower rpm, there isn't enough vacumm to open the valve. That top hose that you have connected is a vacuum line when the thottle plate is closed and a pressure line when the thottle plate is open. If you let off and go back to only partial throttle, the fluttering will happen, and if you let off the gas at a low enough RPM where the vacuum isn't great enough, you will also get flutter.
So, there are two things that you can do to help this out.
1. When you do let off the gas, completely let off the the throttle plate closely quickly and tries to build enough vacuum. (I don't like having to change my driving style, so go to step 2.)
2. If you have a hard upper IC pipe, tape and insert a 1/8 NPT nipple into the pipe. Connect a hose from that pipe to the lower nipple on the Type S. Now, when you are on the gas WOT, the top and bottom nipples of the BOV have pressure going to them, and the spring pressure keeps the BOV closed. But, even if you let off the throttle a litte bit, the pressure going to the lower line will be greater than the pressure going to the top line and the BOV will open. This is the only way the BOV will openat part-throttle let off. Also, if you let off the gas completely and the throttle plate closes, now you have pressure to the lower nipple and vacuum to the upper, which will open your BOV very quickly, which is how it should react.
I have had a type S on my DSM for years and I have mine setup like this. This enable you to keep both springs in there to make sure the BOV stays shut at WOT and hold boost. Mine holds to 30psi, no problem. Do this and you will never have that annoying flutter again.
Eric
You are fluttering because when you lift partial thottle of at a lower rpm, there isn't enough vacumm to open the valve. That top hose that you have connected is a vacuum line when the thottle plate is closed and a pressure line when the thottle plate is open. If you let off and go back to only partial throttle, the fluttering will happen, and if you let off the gas at a low enough RPM where the vacuum isn't great enough, you will also get flutter.
So, there are two things that you can do to help this out.
1. When you do let off the gas, completely let off the the throttle plate closely quickly and tries to build enough vacuum. (I don't like having to change my driving style, so go to step 2.)
2. If you have a hard upper IC pipe, tape and insert a 1/8 NPT nipple into the pipe. Connect a hose from that pipe to the lower nipple on the Type S. Now, when you are on the gas WOT, the top and bottom nipples of the BOV have pressure going to them, and the spring pressure keeps the BOV closed. But, even if you let off the throttle a litte bit, the pressure going to the lower line will be greater than the pressure going to the top line and the BOV will open. This is the only way the BOV will openat part-throttle let off. Also, if you let off the gas completely and the throttle plate closes, now you have pressure to the lower nipple and vacuum to the upper, which will open your BOV very quickly, which is how it should react.
I have had a type S on my DSM for years and I have mine setup like this. This enable you to keep both springs in there to make sure the BOV stays shut at WOT and hold boost. Mine holds to 30psi, no problem. Do this and you will never have that annoying flutter again.
Eric
i kind of fixed it, now it doesn't flutter, it just whistles every time i let off throttle at 4300 rpms and under. i guess that's the normal greddy type s sound? i'll have to mess with the screw tomorrow and see about getting rid of the constant whistling.. haha.