black_fd2134

Ok, so i have a 93 rx7 with a few mods,i am pushing stock boost on stock efini turbos. I want my rx7 to sound like the seven sins rx7 on youtube especially when it comes to the bov. If you havent seen the video on heres the link.

http://www.youtube.com/watch?v=I594HQCHgHc

My question is, can i run the Greddy Type R BOV with stock boost pressure? I know the Typr R comes with two spring options a medium and a harder spring for higher boost applications but is this too much bov for the stock twins?

(and yes i have tried searching for this but gave up after half an hour)

Thank you for ur help!

PercentSevenC

That's not the BOV you're hearing in that vid, that's compressor surge. Any system with a BOV adjusted too tight, or no BOV at all, will sound like that (though the stock twins might sound different).

That said, yes, you can run that BOV. BOVs operate on the pressure differential between the charge pipes and manifold pressure, so the spring is mostly just there to keep it closed under vacuum. I don't know why some BOV manufacturers offer multiple spring rates. There's little reason to do so if the BOV has an adjustment screw.

gracer7-rx7

iTrader: (16)

Try the FAQ thread before searching. There are so many bov threads...

SOB Racing

The different spring rates on the BOV are to keep it closed under conditions when the motor is pulling vacume. It will pull unfiltered air just off idle without the proper spring.

dgeesaman

iTrader: (7)

Boost pressure is not controlled by the BOV on an FD. Aftermarket BOV's are really just noise makers when running the stock boost control system.

David

black_fd2134

Thank you guys for answerng my noob question! PercentSevenC, i know the compressor surge is the high pitch noise in the vid as the turbo spins up, i was talking about the fluttering scoo coo coo noise after. I am still pretty new to turbo charged cars so i could be wrong please correct me if i am. SOB Racing, quick question for ya, (or for anyone else with an answer) which sping would be better for my applicariont? Oh btw i lied earlier im actually pushing 11.5 ish psi or .8 bar sorry.

SOB Racing

Did your BOV come with instructions? I run a Tial and the spring selection method is:

Engine Vacuum Reading / Color Use Spring Between:
- 22 and -23 in/Hg Pink -12 Psi (-24 in/Hg )
-18 and -21 in/Hg Un-painted -11 Psi (-22 in/Hg )
- 14 and -17 in/Hg White -9 Psi (-18 in/Hg )
-10 and -13 in/Hg Black -7 Psi (-14 in/Hg )

black_fd2134

Ok I see. Well I haven't received the bov yet but hopefully it will come with instructions! =) Ty.

PercentSevenC

No, it isn't. That's just the sound of the turbo spooling up.

That's compressor surge. When the throttle plates close quickly, the compressor is seeing a high pressure ratio but low flow, causing it to go into the surge region of the compressor map. The funky sound is air being forced back out through the compressor inlet. This is known as compressor surge, and it's kind of hard on the turbo's thrust assembly.

The spring you use is determined more by your engine's vacuum, not boost pressure. Start with the softest spring, and only go harder if you need it to keep the valve closed at low load. The Greddy Type R has an adjustment screw, so it's unlikely that you'd need the harder spring.

black_fd2134

I see I had it wrong then I thought the fluttering sound was just characteristics of that bov. Thank you for explaining that to me.

Raptyr

my 0.02:

the FD doesnt need an aftermarket BOV when running less then 100kpa/14.5psi.
if you change the intake to a FD specific one, like Blitz SUS Dual, it also makes a
really loud noise.

i you really want that surge sound then just remove the hose with the OEM BOV
and cap off all 3 points where it was connected to. but, as PercentSevenC mentioned
above, i dont know if the stock twins will exactly sound like that... but almost any
single turbo does.

black_fd2134

Well I do really want that sound but not If it's gonna be hard on my turbos.

Rotary SE

iTrader: (1)

I heard stock FD don't really need an aftermarket BOV. But if want to install one, what brand is a bold on for stock twins? HKS BOV? GReddy BOV?

SOB Racing

I love my 50mm Tial

Rotank

iTrader: (2)

HKS BoVs don't bolt on. They are held in place with a c-clip.