HKS Super Sequential BOV

[Endorean]

Hey everyone, not sure if this exact question has been asked.

I'm looking to get a HKS SS BOV on my R33 but I've heard that with aftermarket BOV's and AFM's you can have some trouble.

Does anyone have any opinion on this. Does anyone have one and how was it setup.

cheers.

[rwong20012]

i've got a HKS SS BOV had it for a while with the same problem,

that is after i let it off and chuck it in neutral or step or the clutch after letting off the sound my revs just drop and stall, btw with stock turbo and stock boost sounds like a whistle don't recommend it. but when you run 0.9 bar it sounds better, but i blew my turbo now i've got a garret t3/t4 running 0.6 bar and its sounds alot better not just that stupid whistle sound.

=)

[rev210]

if you like the sound then you can put up with the fact that car will be slower than it was with the stock one.

It will be slower. It might stall on you frequently.

You can get a S-afc to stop the stalling but, again your going to go slower than stock -- you will have that lovely sound tho' and theres no substitute for 'sounding' fast.

[Guest low180]

this may be a stupid question but why would you go slower by just replacing the BOV with an Aftermarket Atmo one?

would it be considerably slower.. but lots of hi performance cars have atmo bov

[Lozza150]

A guess....

A touch more lag??? due to turbo having to spool up again...???

is that right....

[rev210]

The aftermarket BOV's require spring adjustment to set correctly.

This adjustment needs to be spot on to have the level of operation the stock unit offers.

On top of this, if the ecu is standard then the new BOV needs to be a recirulation type. Atmospheric styles cause the between throttle mixtures to be way out resulting in dulled power.

If it aint broke don't fix it.

While on the topic....the factory BOV's are often accused of leaking.

They do.

They are designed to.

The small passage that allows this leakage does not interfere with holding boost (it is more likely to be the crap stock wastegate actuator). The small leakage allows better throttle response in the low to mid range.

[Sydneykid]

Hi guys, and my opinion is...........

A recirculating BOV increases the inlet air temperature as it recirculates the air that has already been compressed (heated) by the turbo. Unless you have a 100% efficient intercooler (never seen one) this can be a problem when you are on and off the throttle a lot (such as in a circuit race car like ours).

The slightly richer mixture that you get from a non recirculating BOV does not completely burn in the combustion chamber and you get a some combustion in the exhaust manifold which helps spool up the exhaust turbine, directly after a gear change. Not such a bad thing. Since we make over 300 upchanges during a race, every little bit helps.

There is also an argument that the slightly richer mixtures helps cool the engine, particularly the combustion chamber and valves. Seen the flames out the exhaust pipe on a V8 Supercar? That's precisely why we tune them (rich on throttle closed, mid to high RPM) to do that.

If you tune the ECU (if you have a tunable one) carefully, you can prevent the stalling problem by judicious use of the throttle closed, low RPM fuel mapping and idle control step points.

Hope that puts an alternative view.

[Endorean]

Well there is certainly some mixed opinions on the use of non-standard BOV's.

Thanks for all the input guys, defenitley some food for thought there.

It was a passing thought, I think i'll do what rev210 says "if it aint broke, dont fix it"

There are plenty of minor mods I can do in the mean time.

Thanks again.

cheers.

[rev210]

sydneykid,

Yeah I've heard that about the atmo BOV. The cooling of piston crowns etc. You can always unplug the hose on the stock unit and plug the hole on the intake pipe, if driving on the circuit. That way you can save more money and convert back for the street duties.

Do you reckon it's better to tune that richness in with a programable ecu on purpose than to have a 'let the chips fall' sort of effect with a stock ecu?

I think you can use the stockie to do both at any case and be pleased with the result. You could do up a quick threaded plug for the intake pipe and make a screw on trumpet for the stokie as well. That way when you a on a 'poser' cruise you can bolt the kit on and when you actually want performance you can plug it back in.

[R33NT]

I couldnt see if anybody has made this comment as i skimmed the posts but i have heard that the unless you recirculate the air your AFM doesnt get the right measurement when the valve is venting and that will cause the car to stall when you go off throttle.

A mate of mine just bought a 1994 GTS25t and he complained about this exact problem. After looking closely at the car he found that it had the standard BOV mounted as it should be but hidden under the piping near the turbo some smart arse had plumbed a HKS SS BOV to give it that little bit extra wank factor!!!!!!!

[R33NT]

Found the following quote when looking at HKS SSQV

HKS SQV

The HKS Super Sequential Blow off Valve (SQV) is a dual stage pull type relief valve. Unlike other blow off valves that are push type, the SQV will not leak under high boost conditions nor under vacuum at idle. Being of a pull type valve structure, the SQV can not physically leak under any level of boost because boost pressure also keeps the valve closed against its seat. The SQV 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 SQV incorporates both a small primary valve for ultra quick activation, along with a larger secondary valve for additional discharge capacity. The SQV 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 SQV 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 blow-off sound along with added visual distinction. The HKS SQV is available as a universal unit for custom applications and also by vehicle specific kits for bolt-on applications. Vehicle specific HKS SQV kits come complete with all needed mounting flanges, brackets, and miscellaneous hardware for a bolt-on installation. For Universal SQV applications, weld-on flanges are available in steel and aluminum for custom installation.

[Nizmo]

Ive just had trouble with my aftermarket blow off valve (which was on the car when i bought it) its leaking air and the revs are low on idle, the car does a shudder and a shake feels like its going to stall but lucky to date it hasnt and the car is on the sluggish side. Ive been recommended to get a recirculative one and told that aftermarket ones do have their problems.

Anyway point of this is - that aftermarket blow offs do give trouble - my car is driving proof!! haha

[R33NT]

What sort of BOV is it (Brand)???

I have heard that the ones that make the most noise are the most inefficient.

I am getting the HKS clone purely because it has a plumb back kit and the theory behind its operation seems more advanced to the standard type of BOV. REV210 feel free to correct me if i am wrong at this stage

[Guest one8tee]

Originally posted by R33NT

I have heard that the ones that make the most noise are the most inefficient.  

them Blitz ones?

[R33NT]

Dunno, its is just something i have been told.

[BATMBL]

THIS IS STRICTLY SPEAKING ABOUT THE HKS SS BOV...

some of the theories said by the people here are proving to be wrong with R33NT's quote, but are rather related as a more generalised view on atmo venting bov.

read the quote by R33NT, as i have read it before on a site somewhere, and im sure this information is very accurate about this particular product. manufacturers, i believe know about these problems that cars can have with the atmo bov, so maybe hks has fixed the problem with its new hks ss bov?

anyways though, I know of a few cars with this bov, and they have never complained of stalling or car going..slower?

my2c

[rev210]

BATMBL,

I have never heard of any cars going faster with the HKS BOV either. That leaves it in the 'cosmetic' category not the performance category. If it vents to atmo then the std ecu will over fuel in anticipation of extra air, not good when the AFR's are crap to start with. If you have a S-AFC or similar they can compensate otherwise give it a miss.

[R33NT]

Or PFC

[BATMBL]

rev210,

yeh i agree with you there, it is a cosmetic thing (or rice boy if you must!), but i am planning to 'chip' my stock ecu, and that way i can change my a/f ratios, it also cuts the 180km/h and a few other things. the way they will do this, by my guess, is by soldering an extra chip on the ecu.

i think the chip is from chiptorque?? not 100%, but i am getting it done through a friend at a cheap price so i'll take it on the dyno with this bov and see how i go!

cheers

[EnricoPalazzo]

Those cars that dont stall are probably fitted with a HKS EIDS computer. It is a idle stabilising computer and is used in conjucntion with the HKS SS BOV so that it prevents stalling. I have one on my R33 and have never had it stall before.