I have been looking into the Synapse BOV and am very impressed. I have constant fluttering with my HKS SSQV. I currently have the HKS BOV installed right after the turbo before the intercooler. I placed it there to prevent compressor surge as much as possible.

My question is: since I am running a PFC which uses a MAP sensor I won't need to run the recirculation accessories for the Synapse BOV BUT will the location alter its performance? I know it is a very ignorant question but I am still confussed on how this BOV releases air into atmosphere while not under boost and doens't affect the idle of the engine.

I also see multiple pics of 3rd gen single set ups running this BOV after the intercooler and am curious if this is simply personal choice OR where it needs to be located.

Any clarification is appreciated. Thanks

Pic attached shows my current set up and my BOV location. Plus I think it is gonna be a tight fit with the new BOV, relocation might be a must have..

 

The most ideal position for a blow off valve is after the inter cooler as close to the throttle plates as possible. so right in or before the throttle body elbow.

BECAUSE. when the blow off valve discharges air it creates a vacuum in the piping. you want that air directed towards the throttle body when its being released. this will theoretically improve response between shifts. the way you have it now the vacuum is drawing most of the air back through the inter cooler back towards the direction the compressed air is coming from. in effect causing the air to do a complete turnaround in the system, once back on the throttle the turbo again has to force the air coming at it back in the right direction.

The synapse valve is open at idle and at idle there is no boost. Therefore there is no air escaping. The air is actually being drawn in through the blow off valve at idle. This is why people not circulating their synapse often put a small filter on it to keep debris from entering the system.

 

Weird because the Synapse video shows that the BOV doesn't suck in air at all.

http://www.youtube.com/watch?v=Iuz99...eature=channel

 

every car is different. I own a synapse and yes it sucks in air on my car (stock turbo fc) I would imagine the larger the A/R your turbine housing is, the less "efficient" at idle the car will be. therefor the higher the chance you would see it suck in air at idle.

 

Great. Thanks for your input. What did you use for your VAC only source?

 

I would say your location for the BOV in the picture is in a bad spot.

You want the BOV as close to the throttle body as you can. because now the air that tries to push backwards has made it all the way back near the turbo So it is difficult for the BOV to vent all the air at its position. If you had it near the Throttle body the BOV can quickly vent out the air before it has a greater chance to push back any further.

 

Well ****! I wonder what I could use to close up that flange and move the BOV over to the straight section of my charge pipe by the oil filler neck?

 

Ummm not to sure, I've seen guys just weld a plate over the old flange but I'm sure something else can be done. So yeah over by the filler neck is a good spot.

 

cool man, thanks for the response.

Anybody else with an FC have this BOV installed and some comments?

 

Couldn't have said it better myself. Putting the BOV before the intercooler creates a "vacuume," "backdraft," whatever you want to call it yourself. Just think simply about what a BOV does, it bleeds off air pressure. If you have pressure in the piping and you put the valve by the turbo, where is the air nearest the engine going to do? GO BACKWARDS!
The idea location for a BOV is as close to the throttle plate as possible...

 

I'm running REW FC and have HKS and am contimplating changing to synapse. Mine is located after the I/C Where is the best place (price/ fast shipment) to get one.

Johny

 

And to the O/P the engine bay is pretty. Just need to move the battery to the passenger bin.


Johny

 

it doesn't make much of a difference. There are lots of cars that don't even have blowoff valves. I'm not saying that you should eliminate it, I'm just saying that it won't make a difference in the life of the turbo, nor will it affect response enough to matter.

what on earth does this mean? if the BOV sucked air in at idle it would have a vacuum leak and the car would run like ****. What kind of BOV creates a vacuum leak? Do you think factory BOV's create vacuum leaks? Why do you think a factory BOV vented to the atmosphere needs a check valve? and what does the hotside A/R have to do with it? if you want better response between shifts get a ball bearing turbo.

The most important thing with a blowoff valve is to

1) make sure it doesn't leak at idle or high boost. This requires proper adjustment of the spring if it is adjustable.
2) make sure it opens under all conditions it should be opening. This requires proper vacuum routing. On my FC I drilled and tapped my ACV blockoff plate for a vacuum source. I have my Greddy Type-S tightened almost completely so that it can hold 21psi without leaking, and it always blows off. And yes, it is before the intercooler, but I'm not saying that is the "ideal" setup. But putting it after the intercooler isn't going to make the car noticeably faster or add any measurable life to the turbo.

 

Thanks Johny. Battery to rear bin is one of my many winter projects.

Looks like I will hit up the fabrication shop tomorrow with my spare SSQV flange.

 

RAY. The synapse valve does suck in air at Idle or vacuum look it up on you tube

Murray LMK where you get your BOV

 

if the synapse BOV creates a vacuum leak from the factory even when properly installed and adjusted, then I am utterly stunned.

 

Your BOV could be wide open and you wouldn't have a vaccum leak. The BOV would have to be located after the throttle plates to create a vacuum leak. And not all OEM charge relief valves are sealed at idle either. If you put your hand in front of an OEM FD BOV/CRV at idle you can feel air moving. It doesn't really matter though because they are plumbed back in to the airbox and receiving filtered air. Some people have also modified the stock BOV with a stiffer spring.



And yes, the ideal location is close to the throttle plates, however I'd be surprised if you saw a large difference in performance one way or the other.



*edit* There would be issues on a MAF system, but the OP stated he is running the PFC map only.

Also, I have a friend with a synapse BOV on a subaru and it had a crude check valve on it to prevent issues with MAF systems.

 

Ok for those of you who still don’t understand how the synapse blow off valve differs from others I’ll go into further detail.

First off.. yes, the factory fc blow off valve sucks in air at idle. To vent it to atmosphere you need a check valve.


The synapse blow off valve is a pull type valve. to put it simple, if you are not on the gas the valve is WIDE OPEN whether sucking in air or not.

The valve only shuts to accelerate. Once off the throttle again (shift gears/ lift off throttle or at idle) the valve opens to release the boost. once back on the throttle again, the valve shuts so you can build boost. simple as that. This virtually eliminates compressor surge because the valve will not cut the discharge off too soon causing pressure waves in the system because unless you hit the gas again the valve doesn’t shut at all. This lets every last bit of pressure out until there is no more to let out. Then since the valve remains open -unless you hit the gas of course- the valve will suck in air (depending on the car)

The video he posted of the bmw.. Apparently the hot side of the turbocharger is so small and/or efficient (quick spool almost no lag) that the turbo at idle is flowing more air than the engine actually needs at that moment. Normally at idle like on our rx7s there’s a high vacuum in the intake piping sucking air into the synapse. Because we usually go with large A/R turbine housings for better high end performance, sacrificing spool up time and low end power. The bmw’s turbo is flowing more than enough air so it has a surplus of air and the synapse is discharging at idle what the engine does not need. Not necessarily does that mean the bmw has a positive intake pressure at idle don’t get me wrong. Completely different cars completely different scenarios.

because the synapse sucks in air at idle on most cars. they offer a "anti-stal devide" which is just a fancy check valve in effect. Useful for cars with mass airflow sensors.

 

 

hmm .... so does that mean your BOV needs a air filter ?? hahaha

 

if you are runing a stock mass airflow system on your fc then no. you have to purchase the anti stall device from synapse OR recirculate the discharge.
http://www.youtube.com/watch?v=VWRXSKYrr8A

this rx8 doesn't need the anti stall but this is what it looks like

 

i'm running the synapse bov on my 60-1 setup. I love it.

 

Sorry for bustin in on your thread but I just purchased a synapse bov for my Fd and am looking for the same setup,to weld it on the same side as close to the throttle body as possible.What flange and size did you get for welding to the ic pipe?Did yours come with a stainless steel flange?
Thanks

 

if u dont use bov @ all the pressured air when u let go the throtle hits the throtle plates and hads back to the turbo and makes almost bov like sound comming out of the turbo,

so same principle if u have the bov far from the throtle body air starts traveling back and u loose responce,

so if u want it louder keep it where it is, if u want it more responsive relocate it closer to the throtle body

 

I have a synapse on a RB25 and it works great. For cars running a MAF you need to run it recirc or buy there anti stall kit. The Synapse will open in vacuum until boost is applied. The anti stall is a spring on the other side to keep the valve shut under vacuum. The valve doe not leak at all under boost and does not have to be adjusted. Mount it close to the throttle body to stop all reversion and keep the charge energy up.

Dustin