HKS BOV-Weird Noise

[hawaiiboy]

I just installed a BOV on my evo and it sounds great, except when I dont accelerate hard. When I am just cruzin the streets and dont make any aggressive shifts, the BOV valve makes a sputtering sound, almost as if its struggling to let the air out. But under hard shifts, high revs, etc., it sounds great. That loud "whoosh" sound we all love makes everyone turn and look. But is that sputtering normal? I've heard some other cars around(sti, eclipse) and they dont make any sputtering sounds. Please help me out by letting me know whats going on and if I should adjust it or just have someone look at it? Remember, I'm in Utah...There arent too many shops around this side. Mahalo for your help!

[tama_mog]

that is fluttering and yes it's normal,u can minimize it by turnin ther spring softer but @ lower rpms in higher gear,u'll get some fluttering.

[DTunedEvoX]

Yes its completly normal .. Your not generating enough boost to vent out to the atmosphere so the little boost you do generate, it lets it out - thus sounding like faint flutters because theres not enough pressure ...

BTW - it was like that on my WRX and on a friends STi ... Its completly fine =D

[hksevo8]

The flutter is caused by the BOV being a push pull type of valve. Under higher boost levels, the valve opens completley allowing for a quick escape of the compressed air in the intake track. Under low boost conditions,the valve opens only partially. No worries, and if you bought the BOV kit for the EVO, you really do not need to adjust the spring tension. The factory setting is already pretty much on target with what you need.

[hawaiiboy]

Thanks alot guys for help. The fluttering sound that you mentioned is a more accurate description of what it sounds like...its just good to know that someone else has heard it before; it's not a fluke with the BOV. I took it to a shop in Salt Lake City and the guys said that I could minimize the sound by tightening it but it sounds like I dont need to. Thanks for help. You put my worries to rest!

[Boosted]

That loud "whoosh" sound we all love

i fuckin hate that sound specifically the loud SQUEEKY WhOOSH of the HKS

[trinydex]

hey hksevo8 i've been curious about this for a while... why do you say the fluttering occurs? i know the hks is a pressure induced closing valve, so the pressure holds it closed. but doesn't that mean it only requires a light spring tension force because any vacuum will open up the valve? and you don't want the spring to be too stiff because then you'd be leaking boost all day long. am i completely wrong in my understanding of how this thing works? and how then does the fluttering occur?

how can your callsign be boosted and you hate the woosh sound? haha

[rino]

I just installed a BOV on my evo and it sounds great, except when I dont accelerate hard. When I am just cruzin the streets and dont make any aggressive shifts, the BOV valve makes a sputtering sound, almost as if its struggling to let the air out. But under hard shifts, high revs, etc., it sounds great. That loud "whoosh" sound we all love makes everyone turn and look. But is that sputtering normal? I've heard some other cars around(sti, eclipse) and they dont make any sputtering sounds. Please help me out by letting me know whats going on and if I should adjust it or just have someone look at it? Remember, I'm in Utah...There arent too many shops around this side. Mahalo for your help!

are you recirculating?

[hksevo8]

hey hksevo8 i've been curious about this for a while... why do you say the fluttering occurs? i know the hks is a pressure induced closing valve, so the pressure holds it closed. but doesn't that mean it only requires a light spring tension force because any vacuum will open up the valve? and you don't want the spring to be too stiff because then you'd be leaking boost all day long. am i completely wrong in my understanding of how this thing works? and how then does the fluttering occur?

how can your callsign be boosted and you hate the woosh sound? haha

SSQV Blowoff Valve (Super Sequential Blowoff Valve) (more)





The HKS Super Sequential Blow-Off Valve (SSQV) is a dual stage pull-type relief valve. Unlike typical push type blow-off valves, the SSQV will not leak under any level of boost because the boost pressure in chamber "C" keeps the valve closed against its seat (Diagram 1). The SSQV releases excess boost when there is a pressure alteration in chambers "A & B", not by the rate of boost pressure or vacuum in the line. This ensures a quick valve response and complete closure during idle. Many competitors use a push-type blow-off valve design with a large valve to accommodate high boost / high horsepower applications. These large valves react slowly and require high pressure to open, and are not able to activate and prevent compressor surge at light-load conditions. On the other hand, smaller, fast reacting push-type valves do not discharge the airflow capacity required for high horsepower applications and tend to slowly open and leak as boost pressure overpowers the spring. For maximum performance, the HKS SSQV incorporates both a small primary valve for ultra quick activation, and a larger secondary valve for additional discharge capacity. The SSQV is engineered to initially open the small primary valve at light throttle and load conditions (Diagram 2), then sequentially opens the secondary valve for additional relief capacity under high boost and load conditions (Diagram 3). The SSQV is constructed of polished billet aluminum, which ensures long-term durability and a high luster look. The mounting base utilizes a circular mounting flange that combines with a C-clip snap ring and O-ring gasket to insure an excellent seal. The triple-fin discharge port design produces a powerful, unique and aggressive blow-off sound.

The HKS SSQV is available in vehicle specific kits or as a universal unit for custom applications. Vehicle specific HKS SSQV kits come complete with all mounting flanges, brackets, and miscellaneous hardware for an easy installation. For Universal SSQV applications, weld-on flanges are available in steel or aluminum for custom installation.

this is the best explanation I can think of for your question.

[G-UNIT]

The flutter is caused by the BOV being a push pull type of valve. Under higher boost levels, the valve opens completley allowing for a quick escape of the compressed air in the intake track. Under low boost conditions,the valve opens only partially. No worries, and if you bought the BOV kit for the EVO, you really do not need to adjust the spring tension. The factory setting is already pretty much on target with what you need.

exactly. don't adjust the screw if you bought the kit for your car. it's preset from the factory.

also if your not recirculating you will need the hks eids to keep your car from running rich & stalling.

[trinydex]

i already read that, in fact i hav ethe catalog that has the cutaway diagrams of the ssqv, it does not explain why there is fluttering but i guesss what you mean is both valvaes open slight when you hit that sweet spot between a full purge and when the two valves are fighting over who gets to open and what not.