the mike

iTrader: (2)

So I installed the HKS SSQV I bought used, fully recirc. My question is....how much flutter is too much?
I have read every post with the words "HKS", "flutter", "SSQV", and they all say that you will get low boost flutter, but this thing goes on for like 4 seconds, tapering off slowly. I don't want to start going nutty on the adjustment bolt, but it is a little excessive IMO. The sound clips I have heard don't flutter this bad. Wht the heck.
If it helps I have an ARC induction box and am catless right now.

Any ideas, or am I just being paranoid?


mike

EvoJason

Yeah, I think 4 seconds is a long time. My friend has one on his Evo 1 and it flutters for 1 second or less. I dont know about evo 8's too much, but again, 4 seconds is way too long. Adjust it a little and go from there.

the mike

iTrader: (2)

Did some thinking about it. The extended flutter only happens when vacuum is applied to the BOV. Such as when shifting out of gear off of boost. As long as there is vacuum to the BOV the flutter is fairly long.
When the boost is high(22 psi) the flutter is short, one or two little flaps. I don't believe there is any signifigant amount of compressor surge. The only jerkiness is in the driveline, both letting off the throttle and getting back on the throttle.

still wondering....




mike

MalibuJack

iTrader: (5)

You can lighten up the spring tension on the secondary valve (the only adjustment) so it opens easier when its primary valve kicks open.. That will allow it to vent easier and let off more pressure faster at low boost. Sometimes that helps.

If you find your RPM's climb between shifts you may have to do that anyway..

the long fluttering sound isn't harmful, just annoying.. the primary valve opens under vacuum, when there's enough pressure to cycle the secondary valve, it opens, so depending on the amount of residual pressure in the upper intercooler pipe, it'll flutter.. You can either get it to open real easy, or firm it up so it doesn't open easily at all, but its a compromise since its MORE important to prevent RPM Rise between shifts, and compressor surge... But it does take some trial and error.

eve-slow

iTrader: (68)

Doesn't the long flutter just mean that the pressure is being let off a little bit at a time? So getting in to the next gear you may not have lost all of your boost? You hear some of the real high hp Supras at the track with the HKS BOV blowing off for a rediculus amount of time. I don't know for sure, but I do know MalibuJack probably know much more on this topic (or any EVO related topic for that matter) than I do. What do you think MailibuJack?

MalibuJack

iTrader: (5)

Well, if it blows off for a really long time, yes, it means the boost is holding longer, unfortunately that could also mean compressor surge. But I suspect he's talking about the fluttering at part throttle.

IF you want a BOV to work right, it has to blow off adequate pressure between shifts if you let off on the gas, if your not producing engine vacuum, it shouldn't blow off (Flat shifting... which is incidentally a very bad thing for a stock evo drivetrain)

Here's the situation that I experience with my car.. If it doesnt vent aduequately, RPM's rise between shifts, also, you'll get compressor surge at other times.. If its configured correctly it should only vent for as long as there's engine vacuum, once it starts producing boost again, it should close completely.. If it flutters for a very long time (longer than your shifts) then it needs to be adjusted.. However part throttle driving is a different situation, the car is under very low boost, and frequently under vacuum.. So if the car is experiencing vacuum in the intake (throttle blade closed) and there's still positive pressure in the upper pipe, it should be venting until the pressure has dropped, otherwise you will get compressor surge (or RPM rise as there's excess pressure in the pipe, so if your throttle blade is partly open, the excess pressure sneaks by, and causes the RPM to rise, its bad for two reasons, with enough pressure and at a high enough RPM, it could rise past engine redline, but whats worse is it could end up being unmetered air since the car thinks there's less air (load) at the time its happening and can run lean when it happens.)

Here's what I've experienced with different valves..

Most diaphragm valves that are the push type (Held closed by spring pressure and pressure in the diaphragm against the valve) have to be adjusted in such a way where under engine vacuum, it stays closed under most circumstances, but will open easily when there is greater positive pressure in your upper pipe to overcome the engine vacuum reducing the spring's tension (10psi spring, -5psi of pressure, upper intercooler pipe pressure should be around 5psi or more and it will vent) when its at around that balance point it will flutter, if its greater, it vents... under pressure the value is additive (more or less, this is kinda simplified) you have a 10psi spring, and 10psi of boost, it should stay closed at 20psi assuming the pressure on the diaphragm holding it closed provides a 1:1 force which most dont..

Anyway.. the HKS SSQV works differently, the pressure keeps the valve closed, the vacuum source only opens the primary valve (the whistling sound like blowing through a straw) when the valve opens, excess pressure can escape until it cycles into a secondary chamber which forces the large valve open against the spring.. if the pressure is too low, it opens easily and may flutter alot, if its too tight, it may cause compressor surge, and bark (chirp) THerefore on the SSQV, Flutter is normal at low loads and part throttle driving, the key is that it immediately closes when boost builds again, and will vent adequately under most driving conditions... thats where the adjustment comes in.

FWIW, the stock DV and the 1G DSM valve is always partially open at idle (in some cases you can hear it whistle or squeak when driving around at low RPM and the engine is under low boost or vacuum) but under pressure it should stay closed, but neither holds boost well over 20psi and leaks slightly (though the crushed 1G DSM valve isn't as bad)

This is why running a MAF on a car, and running a VTA Blowoff valve may work on some cars, and work poorly on others.. If you adjust your valve to stay closed at idle, you'll hurt part throttle drivability and get compressor surge.. If you adjust it loose enough to not get surge, it will almost always be partially open unless your under boost, and therefore you'd get stalling.. (Always Recirculate if you run the stock MAF for this reason)

I hope this info explains things a bit better.. It seems more like a ramble to me today.. LOL

GreedMOTO

iTrader: (3)

Read this...it might help too....

https://www.evolutionm.net/forums/sh...ad.php?t=88637

the mike

iTrader: (2)

Yeah, I guess it's set OK. The flutter stops the second that vacuum is removed from the BOV, when getting back on the throttle for example. I don't seem to get any RPM rise between shifts. And, like I stated earlier, the only shudder I feels seems to be driveline related, not compressor related.

If there are more opinions, feel free to post them up. I am always listening.