Blow Off Valve! Return (Bypass Valve?) or atmospheric?

[Brando13]

Ok guys, Time for me to get a new BOV..

We're going for horsepower and reliability here.

What kind of BOV should i get?

Or should it be called a Bypass valve?

Vote and name your manufacturer (Tomei, Blitz, Greddy, ARC, etc...)

Thanks guys !!!

[Skym]

Im fitting a Synapse BOV on my car. It has no diaphram like most BOV's have that slows down the reaction time of BOV (causes surge sound). It depends on how you connect Synapse BOV to engine via hoses which determines how fast it reacts. Installation is where most have problems and in some cases cause problems with Synapse BOV.

This Supra puts down 908whp with a Synapse BOV while running 34.5psi from a T51R turbo (I gather in Canada) -

http://www.youtube.com/watch?v=P0aHguIN00w

Dyno chart to prove the whp (post no 132) -

http://www.supraforums.com/forum/showthread.php?p=7021602

Supra with 829whp, T51R turbo, Synapse BOV -

http://www.youtube.com/watch?v=A6KB5tAFYF8

If good enough for those cars, good enough for my car.

[kengeroo]

blitz

[NismoS-tune]

Recirculating is best if you're running MAFs. Blitz, GReddy, HKS are nice but Synapse is maybe better (newer technology). I decided to wait till synapse was around long enough to know if they're really good (I'm sure they are)

[kengeroo]

btw are bov legal in Canada ?

[DJ]

what about no bov

[Velders]

what about no bov

My thoughts exactly, that would've been my choice as well.

And yes they are legal in Canada, why wouldn't they be?

[kengeroo]

it seems like in the states they are illegal,,, couldn't find any stuff on them for canada regs..

[Skym]

Synapse BOV has it's problems, it's not perfect. But they are fixable.

What makes it easier to install with latest update of Synapse BOV, is they have now changed external boost feed (port C) to internal boost feed (just like stock BOV) which makes installation alot easier on a RB engine.

It's as simple as fit flange, mount BOV, connect vacuum lines to back of BOV, fit new recirc hose and your done. No adjustment necessary. Most aftermarket BOV's need the correct spring inside to match vacuum of engine (if you fit cams, vacuum can drop. Or if you raise, drop boost level which affects what spring is used), setting BOV to soft or hard to make it work, etc. Alot of unnecessary hassle.

I want to do a install thread to show how easy it is to install this Synapse valve on a RB20DET and what to look out for and parts needed for install which was the most frustrating part, as it was a custom install. The manual they provide is only partly useful, as it's for universal installation, not car specific and doesn't show how to install flange, etc. But not sure if this manual has been updated since I bought my Synapse BOV.

[Brando13]

hmm cool..

should i go back to dual BOVs then cause i think the previous owner put in a TurboXS RFL single in tehre and blocked the other line closed


also is the spot behind the bumper the best spot for a BOV or do you guys move them elsewhere?

[Skym]

GTR runs 2x stock BOV behind bumper on drivers side. Synapse BOV is the only BOV I could find that has no diaphram and can recirculate when using MAF. If ECU has MAP sensor, you can recirculate or dump to atmosphere. But recirculating provides the best transient response and increase in transient hp (when coming back onto throttle after gearchange), etc.

There have been a few cases of 20-24hp gains from fitting this Synapse BOV over leaking BOV (increase in hp, torque throughout powerband) and 9hp gain in transient hp on one of the cars with 20-24hp gain in hp. Can see a leaner A/F ratio on dynograph, so BOV is doing it's job by letting boost reach engine, not being recirculated by leaking BOV and making turbo work harder.

Synapse BOV on a R32GTR with single turbo at Almasi (Canada?) getting dynoed (550rwhp) -

http://www.youtube.com/watch?v=VM_og71DCyw

When driving (can hear BOV and no surge sound) -

http://www.youtube.com/watch?v=IP0IV0sZgHE

I assume port C is connected (older type Synapse BOV before revisions were done).

This is what a Synapse BOV sounds like on RB20DET without port C connected (Port C helps BOV open quicker) -

http://www.youtube.com/watch?v=H0OBVk_UTMI

Even without Port C, Synapse BOV opens.

[NismoS-tune]

btw are bov legal in Canada ?

...wow.

[archaeic_bloke]

i run 2 x blitz VD's... love them.. and yes they are VTA (Vent To AtmospherE)

[frankiman]

i bought 2x HKS SSQV this winter and will be installing them in the coming weeks,
bought these to correct boost leak at higher rpm, and because the SSQV design releases pressure faster than common BOVs
they will be recirculated, for better back-on-throttle response, and fuel economy

though i still have to source the recirc fittings, since they did not come with..

[Skym]

As far as I know, most BOV's on the market still have a diaphram. It's like pushing a balloon against a door and balloon collapses a little bit before door moves. So basically BOV opens slower. The benefits with piston design inside BOV is it's not affected by heat from engine (on GTS RB engine this is important due to BOV sitting above engine), faster reacting.