I reccomend greddy or crushed 1g over anything else. Dono what HKS engineers were thinking, absolutely horrible.

 

WHAT? Please explain.

 

im kinda confused on that one as well

 

Heres the deal. A properly tuned HKS bov, on a small turbo, on a car whose owner just drives around under boost then slams the throttle closed quickly between shifts wont notice much of a problem. But for those who have huge turbos, and those who drive their car like a normal person daily will get surge left and right. Ever step on the gas on the freeway, build up boost, then slowly let your foot off? WHat happens with the HKS?? Helllla compressor surge. Enough to shake your car and wrecks havoc on your turbo. Normal bovs dont do this. This is because the HKS is actuated by vacuum (pull type valve) not boost pressure like all other well designed valves. Its a good marketing design because they can say it wont leak under high boost, but any high quality bov can be tightened enough not to leak anyway. So when the throttle is slammed shut like i said earlier, the rapid change in vacuum fully opens it and you dont have much of a problem (with a small turbo that is), but under normal driving it can destroy a turbo. With bigger turbos that keep spinning between shifts you will most definitely have a problem because the valve never stays open long enough and you surge anyway. I have experienced this personally an finally sold it for a type s and couldnt have been happier

 

Heres another study done by a guy on my local forum for his own curiosity, and I couldnt agree more. Hes tested just about every bov out there free from bias:


"Basically, I disected the valve to do a writeup on why it's such a piece of ****. I don't like the overall design of the valve. It's a neat design, but for any practical use for protecting against compressor surge and shifting is non existant with these valves. I have used every single popular BOV there is, and than many in between. In reality, it's a pointless knowledge to have because a BOVs only purpose is to keep compressor speeds up in between shifts, and to lighten up the amount of surge the compressor sees. With that, in my experementation I found that the previous ssqv I had owned was a taiwaneese fake which basically made my findings void hece why I bought this valve. The real thing worked MUCH better than it's cheap counterpart, but it still did not even come close to how a good BOV should perform. It had a neat sound, but got VERY annoying after a weeks worth of use. I am done with the valve and experementing with it and did not need it as I have reverted back to something that works MUCH better.

So why does the ssqv suck? A normal BOV such as any stock bov, and most aftermarkets use a pressure differential between the IC pipe and the vacuum diaphragm to open/close the valve. When you let off the throttle, vacuum pulls on the diaphragm and boost pressure pushes the valve open. Very simple concept and works wonders. The ssqv on the other hand uses ONLY the vaccum line input for actuation. There is a diaphragm in the ssqv with a small bleeder hole. Under boost, the back side of the diaphragm is pushed toward the body of the valve until the pressure bleeds through the diaphragm. When you let off the throttle vaccum pulls the diaphragm ONLY pulling the little purple valve that resembles a dogs erection. The valve remains open until the vacuum bleeds to the other side of the diaphragm. So the big difference is that a normal BOV is acutated based upon pressure differentials between the intake manifold and IC pipe, and the SSQV is only actuated based upon pressure changes in the intake manifold with no regard to IC pipe pressure. See the problem? The SSQV is only open as long as the diaphragm can bleed air. With small turbos that have really short pressure surges, the ssqv may work fine. With large turbos that take a long time to spin down the ssqv will close prematurely and cause the turbo to surge. Next problem is, as mentioned earlier only the purple dog boner valve is actuated. The black valve floats on the purple valve. This means that most of the time, the purple valve opens just enough to vent pressure and the black valve never opens. You will know this when you get a series of chirps. This series of chirps you are hearing is compressor surge fluctuating though the small valve. A properly tuned ssqv will let out a very slight chirp than a woosh sound meaning the black valve has opened. The valve was designed for more sound and little functionality.

When I had the valve on my car, it had somewhat poor low end surge control as the purple valve opened slightly. The sound resembled a bad wheel bearing. Quick full boost let offs had good response with very little chirp and a woosh indicatiing the big valve opened. On boost slowly letting off the throttle (freeway driving) the valves response was extremely poor. It surged ALOT, and opened way too late. WOT shifting was also poor as the big valve could not open quick enough and I lost boost when getting back on the throttle after shifting. This valve did work much better than it's cheap replica but it still does not serve any useful purpose in a high performance based application. "

 

i will agree that this bov is not really that great on a car with a MAF or any car that must recirc. However this BOV has been used on many high HP applications and are used by alot of people for a reason. That the are great for very high boost applications. So dont say in general these are bad BOV's because hard data proves they are not. Almost anyone running a standalone system wants this BOV. Alot of the High HP supra's and evo's run this as well running over 30 psi.

 

but usually the ppl w/ these high hp cars are running the race ssq valve

 

to each their own, if you like it get it, but i would NEVER reccomend it. I am simply listing its downsides, which greatly outweight the fact that it can hold 30psi, which even the greddy type s can. For those running more boost than that (which im 100% sure no one on this forum does), the tial works just fine.

 

just so you know, your wrong there as well

 

lol F.O.G runs34-35 daily on his. nd if I can get race gas often ill be in the 30PSI range. I am on a HKS SSQ but i am also looking to swap it becuse of the erge problem it is really bad on the highway and I dont want to hrt the new turbo when it goes in soon. FOG is running the Tial. ill prob switch to a forge RS. either way the SSQ is not ery good on cars with MAFs but for 30+ PSI the supra guys love it. some of them running just short of 50PSI on duel HKS SSQs and will stand behind it 100%. then again no one here is close to 1000HP or 50PSI lol.. FOG is the closest with 624HP at 34PSI lol