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HKS SS BOV at stock loactioln

1255 Views 6 Replies 2 Participants Last post by  stoker6
i replaced the stock BOV w/ HKS SS BOV. Work was done by SP engineering. Sometimes it sound like psstttt, which is perfect and normal but sometimes it sound like it cant breath and chocking (kinda like pu...pu......pu) while release air slowly and take several times to release all the airs. Is this normal?
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I also just put one of those in. Yes, that is the noise it makes. I have noticed that it makes 4 distinct noises. I kinda think it now sounds like a wild turkey under my hood. Some funny noises come from it at lower trottle levels. besides the high piched shreek, it lets out a low warble too. This is the lower pressure release.
I have the same thing going. I asked about it here a couple weeks ago and guys seemed to think it was normal. Kinda sounds like compresser surge to me though...
I have the HKS SS Bov and it only makes one type of noise. The only difference is that it gets louder, but it still makes the same type of noise. Try calling HKS and see what they say. I don't own a Supra so this info I'm getting is off my RX-7 Twin Turbo.

Also, does anyone knows what the screw on the HKS is for?
Here's the deal, boys...

The BOV requires a decent volume of air to open it. When under boost, you will hear the sound it should make. At light throttle and low rpm's, the air is not enough to open the valve, and it goes through the air cleaner. No problem, however, as the air volume is too small to cause any turbo damage. This can be adjusted at the BOV screw, but don't go too light or the BOV can leak under acceleration. Kinda what you get with an HKS SSBOV. I have one too...
Actually I think the SSBOV is a pull type valve as opposed to most others which are push type. The more you boost the tighter it gets.

I notice three different sounds with mine. One is the fluttering with very low boost, one is with medium boost when the valve opens part way, and one is with high boost when it opens fully.

Here's a diagram from mkiv
I only hear one sound -- that's because I use the stock one also. I have the screw on the HKS loose. This should allow the pull release mechanism to operate more freely.

Perhaps using the stok bov also makes the point that it has better response for lower boost pressures while the ssbov has better response for higher boost pressures.

I never notice the HKS until after 1.0kg/cm2.
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