Austarion

just what does a Sequential blow off valve do?

Something to do with the internal structure of it.

The HKS Super Sequential Blowoff Valve (SSQV) is a dual stage pull type relief valve. Unlike other blow off valves that are push type, the SSQV will not leak under high boost conditions nor under vacuum at idle. Being of a pull type valve structure, the SSQV can not physically leak under any level of boost because boost pressure also keeps the valve closed against its seat. The SSQV is actuated by pressure alterations only, not by the rate of pressure or vacuum in the line, which ensures a quick valve response and complete closure during idle. On typical blow-off valve designs, a large valve is utilized in order to accommodate high boost / high horsepower applications. However, these large valves tend to react slowly and require high activation pressure to open, therefore are not able to activate and prevent compressor surge at light-load conditions. On the other hand, smaller, fast reacting valves do not discharge the airflow capacity required for high horsepower applications and tend to creep open and leak as the boost pressure overpowers the spring on these push type valves. For maximum performance, the HKS SSQV incorporates both a small primary valve for ultra quick activation, along with 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, then sequentially opens the secondary valve for additional relief capacity under high boost and load conditions. The SSQV is constructed of polished billet aluminum, which ensures long-term durability and visual appeal. The mounting base utilizes a circular mounting flange that provides exception flow and complete secure mounting via a C-clip snap ring and O-ring gasket. The triple-fin discharge port design produces a powerful and unique aggressive blowoff sound along with added visual distinction. The HKS SSQV is available as a universal unit for custom applications and also by vehicle specific kits for bolt-on applications. Vehicle specific HKS SSQV kits come complete with all needed mounting flanges, brackets, and miscellaneous hardware for a bolt-on installation. For Universal SSQV applications, weld-on flanges are available in steel and aluminum for custom installation.

Does that help at all?

yep got it magic!

jokes thanks

Also sequential is when one port opens b4 the other, on my GFB Stealth Fx
the plumb back port will release air a fraction before the trumpet port. as one is closer to the cross over pipe than the other. so they open in sequence one b4 the other.
This is my understanding.

So of that jumble of words i gathered this:

*The HKS SSQV uses a pull style valve vs a normal push type so air leak is 'impossible'.

*Sequential BOV's are better because they use a primary and secondary port, the primary being smaller for light loads and the secondary which is bigger for large loads. The secondary works together with the primary in 'sequence' under large loads of pressure.

that's a lot of friggin effort for a friggin valve... frig

These things also make that unique sound (tie fighter) :D

Here is a question Alspos. Apexi also make a sequential valve as in the orange Supra of Fast and the Furious. It looks nothing like the HKS product so how does it work? Does it have same sealing and staging charecteristics?

Auto barn sold a cheap immatation of the HKS product for $250 instead of about $590

Gadget. In response to your question..... GOOGLE. Gotrices question originally... GOOGLE. I don't read what I put up :roll:

I pulled my bosch valve apart to see what made it work. It has a rubber thing and a spring inside.

ive got a mate with a metal lathe, can make em himself, loudest BOV ive ever heard. Holds pressure up to 80psi. Takes a shitload of time to make tho.

This is what I found on the Apexi product.
The APEXi Twin Chamber Blow Off Valve incorporates a revolutionary design in boost pressure release systems. Blow off valves allow built up boost pressure to escape into the atmosphere when the engine is no longer under load. This prevents the pressure from backing up into the turbine compressor housing, causing it to rapidly stop, and causing potentially destructive damage to the turbo. The blow off valve is also adjustable to allow desired amounts of boost response between shifts.

New question) I have 2 Bosch valves plumbed back to the intake. I currently run 10 psi and will increase it to somewhere in the order of 15-18psi. Will these valves hold up under higher pressure? By having 2 does it split/divide the effort of the valves?

No, they'll both see the same pressure, they will just vent half the air each.

its a common statement/ belief that BOV's leak if they "exceed" their operational boost pressure when infact even the cheapest alloy bov from super cheap which we tested at college can hold pressure up to about 60 psi before air leaks out from the threaded adjust part (the anodized blue part on turbo smart valves) the reason for this is.. bov valves work on vacum therefore there must be a vacum line conected to them. vacum only comes from the inlet manifold when the T.B is closed but under boost the vacum line to the bov also has boost pushing the valve shut along with the assistance of the spring. however if the valve is old and has wear in the piston or seat yes it will leak.

I cant see how a 2 piston BOV should leak.

Unless a sequensial BOV is a 2 piston bov, I dont see any advantage.

StazzyBabyYeah wrote:
*Sequential BOV's are better because they use a primary and secondary port, the primary being smaller for light loads and the secondary which is bigger for large loads. The secondary works together with the primary in 'sequence' under large loads of pressure.

A sequential is a 2 piston BOV, the benifet is: A large blow of valve would not work under light load and a small BOV would not vent enough air under large load. A sequential combines both so that no matter what psi has built up it is always releaved so there is no back pressure on the turbo.

As igottasicjb says.....The bov also has boost pushing the valve shut along with the assistance of the spring............

Thats the whole idea, the boost keeps the valve shut on the seat, higher boost... the more it seals.
When the TB closes the diapham in the BOV opens the valve using vacuum.
And it goes WHOOOSH.
Even when using a cheap plastic BOV.
:beer
A.