Killacamster

iTrader: (1)

after reading the thread and gathering the "unplug the BOV hose from the air box" part. i wonder if ti would be a good idea for those who do that to cap off the end of the hose and the port on the air box. just an idea..... any thoughts????

Scrodes

Yes - the airbox should be capped off if you disconnect the line in from the CRV

CloudPump

iTrader: (2)

I don't think a turbo absolves one from the possibility of being a ricer.

-Geoff

Killacamster

iTrader: (1)

now the end of the BOV hose should have a filter of some sort.

CloudPump

iTrader: (2)

Not much point... it's an air relase, not an intake. Air should be filtered going into the car, not out.

-Geoff

Killacamster

iTrader: (1)

so the hose from the BOV doesn't ever intake air? i read that it breathes at idle. could be wrong.

scotty R

iTrader: (13)

just curious on this but what if you were to take out the ABV completely off and just run a solid hose into your intake box. then to install an aftermarket BOV on the intercooler pipe and run the vacuum line from that to where the ABV ran to on the side of the manifold

sort of like this

http://www.greddy.com/upload/file/11541103_bi.pdf

but instead of plugging it have it release into your intake box

Mahjik

iTrader: (1)

That would be called a boost leak.

SA3R

I'm going to be devil's advocate on this one, and throw this out there.

The stock plastic BOV (be it black or brown) is a diaphragm type of bypass valve.
Meaning that during idle, if you unhook its hose off the airbox and put your hand over the end of the stock BOV outlet, you WILL feel air being sucked into the engine, through the plastic BOV.
Try it for yourself. Once you're comfortable that this is fact, keep reading.

Now, with the stock plastic BOV still unhooked from the airbox, slowly raise the rpm by grabbing the throttle at the throttlebody. Keep your hand over the end of the stock BOV outlet. You WILL feel air rushing OUT of the stock BOV.
Once you're comfortable with this fact, keep reading..

By replacing the stock plastic diaphragm-type BOV with a more conventional piston-type aftermarket BOV (think GFB/Turbosmart/etc) you can repeat the two steps above, and you WILL notice that now no air is sucked inwards during idle, and no air is blown out of the aftermarket BOV when you raise the rpm.

Why?

Because the aftermarket piston-type BOV is built differently to stock, and its operation is different. The piston will stay firmly shut during idle and during boost and spool. (BOV operation 101- pressure/vac is equal in the top nipple, to the pressure/vac in the boost hose, thus keeping the piston centralized and shut. It only opens when there is vac in the top nipple, and boost in the larger pipe, thus moving the piston upwards, exhausting boost whenever the throttle plates shut under boost.)

The underlined part is important. Because everyone is missing it, when they say there is no benefit to swapping the plastic BOV for an aftermarket.

The aftermarket BOV holds the piston normally closed during spool. The stock plastic BOV vents air out as the turbocharger spools up.
Now, which BOV in that last sentence, would you prefer, if you wanted faster turbocharger spool/faster boost response? Definitely not the stock plastic BOV.

I have measured a 200rpm earlier initial boost using an aftermarket BOV, versus the stock plastic diaphram BOV. The results were repeatable. I talked to the head engineer at GFB (Brett Turner) via many emails, and he confirms that using any aftermarket piston type BOV would allow quicker spool by a small amount.
I asked Brett why then, would so many manufacturers choose to use the plastic diaphragm type of BOV in their production cars, if they cause slower boost build up, by venting air leading up to boost. His reply was that 'It reduces the perceived turkey gobble types of noises which would be undesirable to buyers of brand new production cars. Manufacturers do not want their cars coming back because the customer says they are making odd noises. By venting (leaking) air in the lead up to boost, the plastic BOV retains quiet operation and keeps the new car customer happy. Also, the plastic diaphragm BOV is cheaper to design and mass produce by companies like Denso, and requires no tight tolerances, as there is no piston that requires tight tolerances to seal. This simplifies the plastic BOV's manufacture.'

Make of that what you will, but I say based on testing and the logic of how the plastic diaphragm BOV works vs the aftermarket BOV, there is credence in using an aftermarket piston-type BOV.

Flame away, because this flies in the face of everything that people have always advocated. I'm not trying to stir the pot here, but I think there is another side to this argument, which nobody has advocated yet..

Sgtblue

iTrader: (16)

^This is also my experience. In fact you could hear it on my car at idle and IIRC, bleeding air at low rpm and load. So I guess we'll both get flamed.

Besides, my kids like the sound. And when you're a fossil like me, it's nice when they want to go for a ride

fd 4 life

would like to go after market bov on my car is there a diy on how to do this

scotty R

iTrader: (13)

link i already provided a couple sections up^^^^ here it is again


http://www.greddy.com/upload/file/11541103_bi.pdf

fd 4 life

best blow off valve for rx7 hks/ greddy want a loud one

fcyaa

Bravo gentlemen!

I'm a new FD owner and also new in this forum so this tread with all the info about the BOV is gold

Thank you! and I'll see you on Saturday at MAZDAFEST!

tonesbones

iTrader: (1)

What's everybody using to block off the port on the air box? I haven't been able to find a 7/8" cap/plug anywhere in town or on ebay. I have a 7/8" silicone vacuum cap from 034motorsports but I'm guessing it wouldn't take very long for it to fail installed in that location.

Sgtblue

iTrader: (16)

Don't remember dimensions for sure but using a black chair leg cap. Plastic but covered with silcone self-fusing tape. Doesn't look half-bad and they last along time that way.

ZE Power MX6

iTrader: (157)

I use a radiator cap from a 626, Mazda deleted the AST in the later model KL power 626, and they capped the radiator hole, that cap is perfect for capping the airbox. Contact Ray, he should be able to get you that part.

FDHoward93

iTrader: (3)

Home Depot sells 7/8 chair leg caps that are black rubber. They slip on, but give a snug fit. Add a small bead of silicone and it's not going anywhere. The rubber is really thick and holds up well.