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Discussion Starter · #1 ·
if anyone is running the hks super sequential bov in the stock bov location with recirculation kit please me know if it sounds any different than stock....or to get the nice whistle do you have to vent into the atmosphere and have the inserts?
 

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its a little bit louder than stock but not even close to the sound u get when u vent. btw good luck getting the recirc kit to work in the stock location!!!
 

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Alpine Hardtopper
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The distance between the two ports for the stock location is pretty darn short. I don't remember exactly, but lets say 6". The HKS unit is probably 1.5" longer than the stock BOV, and it also raises up about 2". If you add the recirc kit on the HKS you're not about 2.5" longer than the stock valve, and 2" higher. To make matters worse, the HKS recirc kit gives you a 3/4" outlet, and where you have to go is closer to 1/2".

Short version...it's going to be nearly impossible to get a 3/4" to 1/2" adapter in to the location you have to work between.

When I bought my car it had the HKS vented to atmosphere and sounded great. I never had any stalling problems, though I know it was adding a lot more fuel between shifts than it should have. I've since gone small single and recirc'd the BOV until I get rid of the MAF. It's still easy to hear, but not really loud like some people seem to like.
 

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Discussion Starter · #5 ·
if it does stall...what kind of feeling is it??...can you put up with it...or is it really really bad?
 

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Alpine Hardtopper
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I can't imagine any incidence where it would stall between shifts. You're back on the throttle and don't even notice the short burst of rich-smoke coming out the tail pipe. Whe it's most likely to stall is if you're reving the engine, then closing the throttle and expecting it to idle immediatly. For instance....you're at a stop light and a little Nissan Sentra pulls up next to you and revs their engine. You rev yours a few times to show you're the biggest/baddest thing ever....it's probably going to die on you.

Lessons to be learned:
1) Even as a Supra, we're not the bigggest/baddest thing.
2) If you like to rev the engine for no good reason, you deserve to have it die on you.

Most people that put the HKS and install kit on their twin turbo Supra do *not* recirc the discharge at all. It's not ideal, but it seems to work just fine.
 

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I got HKS SSBOV in stock location and vent to atmosphere on my car with MAF and never had any problems. But again I heard of stories that some Supra's have problem venting to atmosphere and some don't. I would try installing it and see if it stalls or hesitates. If it will you can try putting your stock BOV back and weld HKS SSBOV on the IC pipe (if you have them installed on the car) that should eliminate the stalling and hesitation problems. Also try searching the forums I know for the fact that topic has been covered lots of times. Because before I bought my HKS SSBOV I did some research.
 

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So there isn't any reason (except sound deadening) to recirculate if you're running without the MAF, or does it still affect fuel control in a speed-density sensor system?
 

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Discussion Starter · #9 ·
the reason for recirculation to best of my knowledge and to what i understand is that if you vent into the atmosphere the mass air flow sensor is not receiving the proper measurement of air. Therefore not getting enough fuel and having the car stall and or either shut down. If i am not correct someone please elaborate more.

and Vitek could you please give me more information about your supra. For example year, automatic or 6spd and mileage.
 

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Alpine Hardtopper
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The reason you recirculate is specifically for ECU's that use an airflow meter to determing the fueling needs. In the Supras case, that's the MAF. It detects how much air is coming in to the engine and then decided how much fuel to add based on that information. If *any* metered air goes through the MAF, but doesn't go in to the engine....there will be more fuel added than there should be. Likewise, if air gets in to the engine that did not pass through the MAF, the mixture will be leaner than it should be.

The reason you can get away with atmospheric venting of the BOV is that it is a very temporary condition (not like a leaking IC hose or something). The only time that the MAF is adding the incorrect amount of fuel is when the BOV is venting. But the moment the throttle is opened again everything is fine.

The above is true for the HKS SSQV anyway. There are other OEM bypass valves that are designed to be open *until* boost pressure is created. If one of those was vented to atmosphere on a MAF type car...it most likely wouldn't run at all.
 

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Discussion Starter · #11 ·
thank you for explaining everything very clearly. Now my question is to you or anyone who could answer it. When does the actual stalling or excess of fuel dumping take place? When your at WOT or when you are coming to a stop? Or does the car shut down only when a sentra gets next to you and you rev the crap out your car?
 

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The excess fuel is only happening when the BOV is open, and the metered air is escaping. For that second (or so), the mixture in the cylinder is very rich. If the car tries to idle immediatly after the BOV has been open (now closed), there is still a fair amount of residual fuel in the cylinder, so it's still running really rich. So rich that the engine usually stalls.

So if a person *must* rev up their engine while at a stop and make cool BOV sounds to impress the fans, they should consider keeping their foot on the throttle for a second or so before letting it idle again. That should be enough time to clear out residual unburned fuel from the cylinders.

Also, in regards to your original question about BOV noise...the SSQV isn't a super noisy one. There are other inserts you can buy that make it a little noisier, but none of the inserts are loud like the BOV's you see with horns on them.

Personally I don't care much how it sounds....I just care how it functions. If it was super noisy, or no sound at all, I only care that the compressor isn't getting stressed by a ton of huge surges.
 

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Discussion Starter · #13 ·
but installing the ssqv isn't going to stress the compressor with a lot surges right?...i mean it does do the job like how it should?
 

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The job of the BOV is to help keep compressor surge to a minimum by venting/bypassing the surge when throttle is closed. I thought the SSQV did a fantastic job when I used it with the stock twins. The small vent opens about as early as the stock BOV, and the larger ones gives a lot more flow than the stock one could dream of.
 

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22urbo said:
the reason for recirculation to best of my knowledge and to what i understand is that if you vent into the atmosphere the mass air flow sensor is not receiving the proper measurement of air. Therefore not getting enough fuel and having the car stall and or either shut down. If i am not correct someone please elaborate more.

and Vitek could you please give me more information about your supra. For example year, automatic or 6spd and mileage.
1994 Supra TT, Auto, 79,XXX mi.
 

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with the recirc its no issue. with the vent method, the ecu will stumble abit in the beginning when u start the first time (you DID remove the battery right??!?!?!?!?) but i found after the ecu learns, the stumble becomes barely noticable. the rpm drop issue w/ vent is really an exaggerated issue, its minor once the ecu adjusts.

i cant speak for auto supras, i heard venting is MORE of an issue w/ them.
 

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Discussion Starter · #17 ·
well i have a 95 6speed with 80,000 miles on it. And i have yet to install the BOV due to the fact that i've been scared of serious idling problems and serious issues with the car dying out. But everyone seems to say that its not a noticable problem so i think i'll get to it soon. Thanks for everyone being so generous. mifesto are you running bov with maf?....and when you say remove the battery you mean just disconnect the positive negative terminals?..anything else i should know for the install?
 

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Trust me the bov and map are fine together the only problems that you would have with the car stalling would be if you wer to do a full throttle accel and push in the clutch and hold it or put it in neutral or if you were to (like the other guys said) rev the car you would have to ease off the gas after reving it instead of abruptly letting off of the throttle. Want a blow off valve without any idleing problems??? Go AEM and use a map sensor with no MAF!! Air is vented to atmosphere before it is read by the speed density sensor, not vented after it's volume is already taken into account!
 

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Discussion Starter · #19 ·
i got a friend who's running single with vented BOV and maf and he has that idling problem...but to tonight i went to a meet and this other guy had the bov vented into the atmosphere although it was welded onto a hardpipe and he did not have a front mount. Where the stock bov used to be is just a closed hose. Mods are intake, downpipe, hks TI exhaust, intercooler hardpipe, and the ssqv. And he had no idling problem WHATSOEVER...he would rev it up and it would catch perfectly....am i missing something or is he just lucky?
 

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With my HKS BOV vented to atmosphere on the stock twins I never had a single idle/stall problem at all. When I went single (still using MAF sensor) I used the same BOV vented to atmosphere and had a few idle/stall problems at first. I then put the recirc kit on and didn't notice any improvement at all...still stalled occasionally. However over a few days of driving the ECU was able to learn and it hasn't been a problem since.

Personally I think that the BOV had little to do with the idle/stall problem. The ECU memory was cleared when I went single and I think it just took time for it to learn idle parameters with the small single in place.
 
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