HKS ssqv
Oooh… There has been instances of people splitting the legacy intercooler in two (endtank blowout) with that BOV.
It is sprung WAY too tight from the factory.
do subaru’s just not like aftermarket bov’s? TONS or rx7 guys have been running hks ssqv’s for years without problems
Edit: I thought I was posting in a different thread, I am an idiot!
There are certain problems with running a BOV in a subaru.
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The Recirculation dump tube is post MAF so when the MAF meters the AFR and a BOV is venting as opposed to Recirculating like a stock BPV would it throws the AFR off. Usually this causes a temporary rich condidtion between shifts.
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The stock BPV has proven to be good to past 20psi. It is basicly a 1g DSM valve flanged for a subaru. If it aint broke dont fix it.
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A turbo bearing failure because of compressor surge has nothing to do with what type of car you run a BOV on it has to do with shitty, improperly sprung, or broken BOVs. It can happen to any car.
thats why i’m asking tho… i’ve yet to read a post like this on the rx7 boards…i even just did a quick search to verify. just seems odd :gotme:
edit i found ONE thread of compressor surge with an hks ssqv on an rx7…and it was at 2psi of boost lol
It could be due to the fact that the turbo outlet is about 9 inches away from the throttle plate in a subaru. And the BOV is positioned mere inches away from the throttle body. Very short intake plumbing with very little volume to fill.
An FMIC’ed RX-7 has plenty of free room to work with between the turbo outlet and the throttle plate. In effect its saved by shitloads of boost plumbing giving room for the BOV to react and since there is so much room the surge is less when the throttle plate snaps closed.
Let’s take a quick look at the BOV (Blow Off Valve) and what it does for you and your car.
First, a quick history lesson.
Q. Where did the BOV come from, who could possibly have made something that sounds so cool?
A. Porsche, Duh. Developed for there race cars (early 80’s i believe) it was patented as a Pop Off Valve. You may still hear some old timers refer to it as such. (AWDrifter)
There, now you have learned something today, and can wow your drunken friends at the bar.
Ok, let’s take a look at what this little gizmo does.
The BOV releases the pressurized air from the intake pipes when you lift your foot off the throttle; either to shift, or just to hear the cool sound.
Now, why do we need to do this? To taunt others in to racing? Just because it sounds cool? Possibly, who knows with those Germans; those may have been underlying reasons, but actually the intended purpose was performance.
When you lift your foot the throttle plate closes, and that air bounces off the throttle plate and makes it way back towards the turbo. When that air gets back to the turbo it will try to spin it backwards (compressor surge).
Now when you reopen the throttle the turbo has been slowed, or even stalled, and needs to be reaccelerated. With a BOV in place, this air would never make its way back to the turbo, and the turbo would be able to continue spinning freely. Now when you get back on the throttle your turbo is still spinning from before, and will spool more quickly.
Lets take a look at BOV placement.
Some will argue that it should be near the throttle body, others say closer to the turbo.
Well, lets look where Porsche put it on their race cars.
Porsche made the BOV part of the compressor housing, and redirected the compressed air to the turbo inlet. Pretty slick, huh?
I am from the close to the turbo camp, and i will explain why.
- The air doesn’t just bounce back off of the throttle plate, there are sharp bends in the pipe, and a giant obstruction called an intercooler in the way.
- By placing it near the turbo you vent only the air that has made it back to the turbo, leaving the rest of the pipe with some pressurized air still in it.
- Having the BOV after the intercooler vents air the ic has already cooled. Kind of a waste, dont ya think?
Placing the BOV near the throttle body seems to be out of ease. Just like the boost pressure reference nipple being on the turbo housing. (We all know pressure in the housing is not the pressure in the manifold) It was just easier, and less costly that way.
Now i am sure you have been reading this and saying to yourself “Hey, i thought the BOV was to keep the turbo from getting surge and damaging it.” It does do that, but that was not its original intent.
And that my friends is the BOV and you.
i’m not sure if my logic is right with placement. perhaps newman or some other train drivers can shed some more light on it.
you dont hear many cases of it, odds are the rotaries aren’t lasting long enough 
yea that was definately an interesting scene yesturday. the ironic thing is i was getting ready to put the stocker back on anyway. :tdown: to bad timing but its gotten progressivly worse over the past few days now that i think about it and all that hard driving the other day finally put it over the edge. well the wevo will be out of commision for a few weeks while its getting rebuilt.
lol now i have to wake up the beast… :bloated:
^This thread is worthless without pix
Now mind you that this is Oil, not water/coolant or otherwise.
SSQV strikes again!
ouch
where’s the one that showed how high it hit the bushes?
haha yea. i just talked to mike about the letter he was sending along with it and he said justin showed him some peices. I was like PECIES???
CARNAGE:
Rather than being the victim of compressor surge, Larry had a massive boost leak. The turbo was overspinning, which superheated the oil which wore the bearings, causing in & out shaftplay. The shaft eventually became so loose it impacted against the compressor cover. The exhaust wheel and shaft snapped off and came out his exhaust as shown, and the compressor wheel spit bits into his intercooler.
I think I just realized how you ended up without a BPV gasket. The stock intercooler on an 06 WRX has an o-ring of sorts used to seal to the stock BPV. There is no gasket persay, but that seal is very important.
When you switched to your big top mount intercooler, it is designed like the 02-05 stock intercoolers in that the flange the BPV mounts to is flat and requires a gasket. Since no gasket was used there was a constant leak. This also explains some of the stumbling at idle.
Did the instructions from Perrin or HKS (BOV manufacturer) mention that you need to use a gasket? I have a Perrin TMIC here, but it’s sealed up and I didn’t want to open it.
-Mike
di he suck any of those chunks in the motor