BOV question - Toyota Nation Forum : Toyota Car and Truck Forums

JspecGTS · 02-24-2004, 09:05 PM

i have a 91 j spec clip coming in and i was wondering can the 3sgte use a open atmoshphere BOV's??? Any BOV recommended?

OEMonkey · 02-24-2004, 10:41 PM

BOV's on this stock car will hurt its performance, mainly throttle response bet. shifts. but they sure sound cool. if I had to choose, I'd get the hks super sequential.

bcrdukes · 02-25-2004, 02:38 AM

The HKS SSQV is one of the most popular BOVs on the market. Most people like it for the "pssssh" sound. Also, other popular BOVs are the Greddy and Blitz.

There's a fellow in Vancouver with a 91 MR2 Turbo who has a loud BOV and the release is probably 5 seconds. All that vacuum release hurt its performance so bad when it came to shifting, the car would stall in the middle of traffic. Saw it with my own eyes.

***MRQtwinturbo*** · 02-25-2004, 08:54 AM

i'm using HKS SSQ also....no idle problems....car runs perfect with it....also vented to atmoshpere....not as loud as my greddy type s was but its a more distinct sound....sort of flutters sometimes in between slow shifts....

starfoxtien · 02-25-2004, 11:08 AM

i also had hks ssq and i tell that thing is a beauty. works perfect on my car. nothing wrong with it. scares people when i go out to the illegals. but i love the blitz and all too. but go with the hks one. its nice

***MRQtwinturbo*** · 02-25-2004, 11:24 AM

^^the sound of my waste gate dumping turns heads now....everyone has the wtf was that look on their faces as i blast by.....

JekylandHyde · 02-25-2004, 01:16 PM

Read here:

http://jekylandhyde.madpowaz.com/bov.htm

mr2freak · 02-25-2004, 04:06 PM

yeah but what if you put the BOV before the MAF sensor? then it doesnt flase the readings, right?

JekylandHyde · 02-25-2004, 08:19 PM

mr2freak, the point of having a BOV/BPV in the first place is to stop pressurized air (boost) from rushing back toward the turbocharger when the throttle plate closes.

That being said, if the AFM/MAF is before the turbo, it would make no sense to put the BOV/BPV before the AFM/MAF. You would, in reality, be venting air in front of the turbo - not the point at all.

You may ask, what about putting the AFM/MAF after the turbo? ... no can do. The air after the turbo may OR may not be pressurized; therefore, the AFM/MAF reading would not be accurate. The air before the turbocharger is never pressurized (other than atmosphere) so the meter always measure the quantity of air for a given movement on the flapper door.

Hope that helps.

The short answer is the OEM BPV is the best piece you can have there. Anything else is a downgrade.

***MRQtwinturbo*** · 02-26-2004, 10:38 AM

what happens if u eliminate the AFM by using VPC...now my bov is set up after my IC and before my intake mainfold....i've seen many others have theirs set up before after the turbo and before the IC..but this is how my tuner prefers with my setup...i'll post a pic of it later on when i get home or if can find the link from work..

JekylandHyde · 02-26-2004, 10:48 AM

Eliminating the AFM will get rid of the problem of venting metered air with an open-air BOV. Unfortunately that is only one of the problems with aftermarket valves.

Aftermarket valves also eliminate the by-pass feature of the OEM valve as described on the link I supplied.

Aftermarket valves (except for one version of the HKS) use a spring-based design. Given enough boost pressure the spring will open compared to the OEM design that seals harder.

Let's say you adjust the spring tension high enoguh that yo uwould never reach that really high boost pressure to open it - what then? Well, then you have a spring so tense that it will not vent under lower boost driving. Using spring type valves is a compromise.

Lastly, a valve with a spring in it will never respond as quickly as the air-based design the OEM uses.

Don't get me wrong, I love the sound of the open vented BOVs, but the math does not work for me.

Piddy · 02-27-2004, 03:38 PM

So what we are getting at here is that the aftermarket BOV adds no performance to the car. The only thing the BOV does is make some noise. That is of course only if you are running a stock turbo setup I would suppose? Otherwise there would be no reason for a BOV.

JekylandHyde · 02-27-2004, 05:15 PM

Yes, aftermarket BOVs are good for noise (which is cool

), but they rob some level of performance ... and it doesn't matter what turbo you have.

The OEM valve is the best valve you can possible have under all conditions except ONE. That condition is if you are flowing enough VOLUMN (huge boost, huge turbo) that requires a larger valve. That being said, the best valve in that situation would be the OEM design but larger.

99.9% of people will never see that level of boost.

Quote:

Originally posted by ishcoleobo
That is of course only if you are running a stock turbo setup I would suppose? Otherwise there would be no reason for a BOV.

Doesn't matter what set up you have.

There is a reason for a venting valve, whether it be a BOV or BPV, regardless of what turbo set up you have. The reason is to stop pressureized air from trying to spin the turbo in the wrong direction.