synchronic piston/pull-type BOV

[fr0IVIan]

http://videos.streetfire.net/video/6...3f0150f005.htm

it's a showcase of the synchronic BOV, illustration of what compressor surge sounds like, a side-by-side comparo between the synchronic BOV and a typical BOV, and some drive-by's to hear the sound.

can someone in here weigh in on the tech involved, and if there is any benefit on using one with our cars?

[062stang]

wow im going to buy that BOV.

in fact that one he was comparing is the HKS BOV which is the same one i have. it sounds great.

but i rather have that synchronic one since the valve opens way faster.

the reason you want to the relieve the boost pressure in the intake tube is because when you close the TB for a shift, the incoming air which is moving at great speeds, slams against the TB plate and sends a pressure wave back through all the piping and the intercooler to the turbo's compressor. this is called compressor surge. the pressure wave can actually damage/bend the comperssor fins.

the BOV relieves the pressure in the tube so hopefully you want get comp surge. this is why i think it is best to mount the BOV between the turbo and intercooler, cuz hopefulley the valve might open before a pressure wave gets there, a BOV mounted closer to the TB may sound louder but since these things open slowly it may allow pressure waves to move past the BOV before it can open. BOV opens when it senses vacuum in the intake manifold.

i like these synchronic BOV because they open fast, super fast, relieving pressure alot more quickly then anything else on the market. plus they have no diaphragm that can rip and leak vacuum.

so not only are these synchronic BOV good for hondas, but they will work just as well for our cars and any other car with a turbo or blower.

i think this is great find fr0IVIan.

so this synchronic BOV is win/win BOV, is there a place to buy or a price on these things.

-umesh

[piratius]

Umesh, you're right in what a BOV does/why it works, and why it's important...but...

The test is somewhat null/void in the fact that the HKS SSQV (the one he tested the synchronic against) also relies on INTAKE PRESSURE CHANGE to open the valve. Sure, it may have a diaphram, but a properly setup SSQV will react just as well when it's set to proper factory settings, and connected to an intake tube that's seeing boost changes. Having looked at how the HKS valve works, it's integral to it's design that it actually be hooked up and have proper spring pressure and intake pressure to hold it closed, just like what they claim with the synchronic

Believe it or not - you don't want the spring set all the way loose - the fact that the synchronic works just as well with the spring all the way out seems a bit odd - and that it would tend to be surge-happy in a street setting. The HKS BOV spring, when adjusted properly, reacts very quickly - if it's connected to a good vacuum source, the HKS will react plenty fast enough to effectively nullify compressor surge.

Anyone else who watched the video - at the end, their BOV sound amazingly like compressor surge - I think that the fact it's set to actuate at low throttle positions really affects and hurts it's performace.

Also - why would you want the BOV to be open at idle on a blow-through car? There's no point to it - on a draw-through MAF setup, I see how it could massively help driveability, but with the blow through setup the S2k was using, having the BOV open at idle was worthless, and shows a downside to their design - if it's not open at all times during idle, it *can't* open during shifts, as the vacuum change wouldn't be enough to overcome the spring pressure.

The way the synchronic valves work is simple - rather than having a permanently mounted diaphram where the center section moves under vacuum/boost, thereby moving the shaft & valve assembly, they're using a sliding piston in a sleeve - and the vacuum pulls it open, and when vacuum is removed, the spring pressure closes the valve. Simple, and elegant, yes...However, if the spring is set even slightly too tight, (since they claim they adjusted it), it'll remain closed even under massive boost changes, resulting in the compressor surge they claim they're better at removing...(but it sounds like they've got their setup wrong at the end of the video!!!) This is where the HKS shines - even if you screw up the spring pressures, and it isn't "open" at idle, when the boost spike hits the valve (that pressure wave Umesh mentioned) it pushes and helps actuate the valve, relieving the pressure. The Synchronic can't do that.

Since only the manifold pressure affects the piston movement in the synchronic, as opposed to the HKS style, where the air pressure spikes/changes in the intake pipe can also actuate the BOV, it's comparing apples to oranges, when the do the "side by side" comparison, since the HKS unit (which looks somewhat like a knock-off, btw) also needs the intake pressure change to actuate.

~Brad