i have a rfl adjustable blowoff valve on my sr. i've seen many different photos of many different turbo engines and have noticed that the position of the bov's are all over the place. some have the bov on the intake piping. some have it on the pipe between the turbo and the intercooler. i have it on the pipe between the intercooler and the intake manifold... what i want to know is if there is an ideal position for it and if there is, why? i have a hose leading from my intake manifold to the bov flange, which one of my friends said would, help expell excess pressure after the charged air enters the throttle body. or i hope it's working that way... any in-depth info would be greatly appreciated cause i feel i need a better understanding of this to make my car even more responsive. also, is there a way to re-circulate the air that the bov is releasing to decrease lag?

 

omg, i'm such a stupid douche. the bov's on the turbo to intercooler pipe is the external wastegates aren't they?????? actually, i'm not even sure anymore. well, any info or disses would be welcome... hahahaha

 

it really is a matter of opinion to which position is best...no position is noticibly much better than the other (though garrett says the bov should be placed after the intercooler....i'd trust their opinion, as they make turbo stuff for a living) i'd just find the position that best suits the space constrictions of your engine... yes, you can and should recirculate your bov...you recirculate it to before the turbo so you don't go lean during shifts

external wastegates are placed on the turbo manifold usually for larger turbos to regulate how much air is going into the turbo so you don't creep, spike, and/or overboost...

 

is it true that bov's can cause stalling? cause my engine's rpm will crash when i don't feather the throttle when i dip the clutch to brake. i'm just trying to find out why my engine bogs cuz i read on wikipedia that because the bov releases air after the maf sensor tells the injectors how much fuel to fire, a bov inadvertently floods the engine... it makes sense but i wanna know how to make it stop cause i don't want compressor surge or engine flooding.

 

Yes, BOV can cause the car to stall.

There should be adjustment screw to tighten or loosen the spring inside.

Or you could re-circ it and get rid of the problem.

 

yeah the main solution to all your bov woes is usually to recirc it... when the bov is releasing air when it's not recirculated, ther maf cannot account for that air, and it may cause you to run rich between shifts, have a crappy idle, bog etc... when you recird your bov, that air that is being released now has a chance to be metered by the maf, so your **** runs good

 

just wondering, could you possibly have the maf after the turbo, and after the bov? like before the intake manifold or something like that..?

 

yes, that setup is called a blow thru setup

 

Wouldnt it make sense to have the BOV right before the intake manifold? The PSI changes through the intercooler.

 

also at the time i didnt have a filter on my intake and my SR would bog and somtimes stall but after i installed my HKS filter it ran perfect

 

yeah thats what most supra guys are doing well atleast there putting it on the cold pipe, I would think that as soon as the throttle closes its the #1 place to pressurise and then cary out that pressure all the way through the system until it reaches the turbo (Surge) or bov. IMO if you would like to avoid surge I would say put it close to the thottle so that it can open up as fast as possible.

I have a question : on a blow through setup would the maf be between the throttle plate and the BOV?

 

thats what i would think to be ideal. have it be hotpipe, intercooler, cold pipe, bov, maf, throttle. but thats just my reasoning. im probably wrong.

 

no that sounds the best, i agree...trying to fit all that stuff between the cold side of the intercooler and the throttle body sounds like fun though ahha

 

Its actually a bit of a debate which is correct and OEMs put them in all different spots, even on different generations of the same car such as an s13 vs s14 silvia.

One way suggests its best near the throttle boddy so that pressure can be release right at the point it is first created by the shutting door and keep in the direction it is traveling.

Another way suggests it should be relatively close to the turbo because the shock wave travel in the reverse direction starting at the throttle body andhave it by the turbo ensures reponse time and that the pressure gets out rigth before it goes back through the turbo.

I say it makes little difference and go with what is easiest.

 

wow, that was like turbo 101 for me lol...ive learned some important stuff today