well, as it says I would like some input on what you guys like as far as blow off valves, I have a procharger F-1 supercharger, 6 speed trans and since it is a higher boost system with a stick I need a better way to control compressor surge than the procharger valves


so far I am thinking about getting the large vortech one. any thoughts?

 

I am running the large Procharger valve with no problems. It was the largest valve on the market untill Vortech released there version of this valve. I purchased mine from Lonnie Pavits, as he had the best prices available.
I hope this helps,
DonB

 

Sorry the pics are cloudy...

 

last one...

 

Wait.... Isn't that ProCharger unit a surge valve? A BOV functions differently.

 

Nope, it's a BOV.

 

I will have to check that one out.

 

It is definately a blow off valve. I have 2 on the car now

It is expensive tho, about $400 with the flange.

 

seems like a lot of $$$$ how big is it?

 

That's odd how you guys say it's a BOV. I talked to ATI a couple of years ago when I realized that one of their Pro Flow surge valves was not sufficient for my setup. It was explained to me that their "best" unit (above) remains open when in vacuum and closed when in boost. This is the definition of a surge valve. This is why I decided to go with a second Pro Flow surge valve. The definition of a BOV is basically the opposite -- it remains closed until a pre-set amount of pressure (boost) is attained, then it opens allowing excess boost vent. Please correct if I'm wrong but I think I'm right.

I myself will be going with the Tial BOV (the first one listed) on my new TT setup:

http://www.diamondstarmotorsport.com/intakeparts.shtml

Willie

 

I've only heard good things from many people about the Tial BOV, I wouldn't hesistate to get it myself if used 1G DSM BOV's weren't so dang cheap.

BOV's aren't supposed to open when you're under boost at all, they open when you let off the throttle and there isn't anywhere else for the remaining pressure to go. The little vacuum line that's above the diaphragm goes to the intake manifold so boost in the manifold will help hold the BOV shut during WOT, and vacuum in the manifold will help open it when the throttle is closed.

I don't know anything about the Procharger valve though.

 

The Tial BOV I'll be getting was one that was recommended by Gale Banks.

Also think about this. A supercharger produces air all the time because it's belt driven. Most of this air is not needed by the engine, i.e. idling, light cruising, etc. This excess air must be vented. This is what a surge valve is for. On the other hand, a turbo does not spool up until needed. Therefore, it does not produce any excess air -- a surge valve is not needed with a turbo. Now let's talk BOV. It is not needed with a supercharged system because the surge valve opens when the throttle is let off. In essence, the surge valve works as a blowoff valve. On a turbo system, it has to have a BOV because it does not use a surge valve.

So now I ask, why would ATI sell a BOV when it's not necessary with any of their systems? It doesn't make marketing sense to design, engineer, produce and market a product that none of their systems need.... I still think it's a high-flow surge valve, as was told to me by ATI years ago. Comments?

Willie

 

Comments? How about this… I don’t see why people bother differentiating between surge, blowoff and bypass valves. In the long run they all serve the same purpose, to release excessive pressure in the ducting between the blower and the engine, with the only real difference between any of them is the way that their signal line is plumbed (or left off) and the fact that a bypass has a fitting so that you can easily connect it back to the plumbing before the compressor. They will all “blow off” given enough of a pressure differential between the inlet plumbing and the signal side.

 

well, i want a blow off valve because they way I understand it when the throttle slams shut a "blow off valve" will vent quicker than the "surge valve" since the surge valve requires vacume

now I know you will think heck blades are shut and now there is vacum from the eng. still spinning. the surge valve will open right up. (well yes but, not as quick as the compressed air is building up in front of the blades) this is why I want to add a blow off valve......... when the throttle slams shut the now instant high pressure forces the blow off valve open and with in milliseconds the surge valve will be open as well allowing the blow off valve to shut.


I think this is the best way I can set my car up since it is stick and running high boost (constant shifting)

 

I’ve never seen any of them that hold significant pressure without pressure applied to the back of the diaphragm. They will all pop open when you slam the throttle shut under boost

Nutshell, it really looks like you guys are getting hung up on semantics.

 

Thanks!
Glad I wasn't the only one thinking that!
DonB.

 

I ended up put a stiffer spring in my stock Procharger surge valve. The stock one just plain sucked. Not it works perfect and is instant when I hit the gas. Also it open super quick when I let off the gas. As much as I like actual blower I find the rest of the Procharger kit to be below average at best. I will be updating some things on mine come this winter.

 

A blow off valve does not control boost a wastegate does.
A blow off valve works in a simmular way as a surge valve. It acctually opens when it sees vacuum to let the excess boost out.

 

are they the things that make the cool shhhhhhhhhhhhhhhhhhh noise?

 

yep its just venting boost cause the throtle shut

 

This company was suggested to me by Gale Banks Engineering:

http://www.agpturbo.com/customer/home.php

They have the Tial BOV I'll be going with and many others.

Willie

 

They're who I got my T3/T4 turbo kit from for my Talon. A++ service, always recommended from me.

 

i have a BOV that holds like 30lbs boost easy. I can't believe how strong hte spring is...anyway...the Bypass amy be more needed for my setup....than a BOV: (so i've bee told"): here is one of my other posts:

I did a search and came up with this thread and some good informative posts. On my setup, I don't have a blowoff valve hooked up right now. My new setup is running okay, but my buddy keeps telling me that I need a Bypass or surge valve, not a blow off valve. He says that it won't run so rich at idle if i get one, because the car won't think there is so much air coming in as it does now. He said that it will also help idle, since i won't be "cramming" so much air into my IAC. He says that if i hook a bypass up, I will have to reset the idle and TPS, and then maybe have to drill holes in the throttle blade to let some air in, so the IAC won't be maxed open (like he thinks it is now) and so that I don't have to have the throttle blades so far open, which is also causing my idle problems. It really doesn't run too bad now, but the idle is a tad low and I can't get it higher no matter whaat I adjust. It really needs to go up about 1 or 2 hundered rppms, cause when it's in gear, it's a little to low. I did make up a temporary bypass that vented directly from the discharge to the intake duct, and it started surging a lot. He said that even though it was surging worse now, once I had the proper chip burnt and drilled holes in the TB blades and install the surge valve it would improve. He thinks that The IAC is getting too much air and is fighting the other sensors and whatnot. He thinks I need to leak some air into the TB, UNMETERED...Also (FYI) the motor seems to like more than 16 degree base timing,...but it is a big cam. My total advance seems to be a little high at about 36 degrees. I will correct that with the chip. Anyway, will what he is saying help get my idle a touch higher, less rich and better even though when i rigged up a bypass it seemed to surge? Also, I think my BOV bung is about 1 1/2", and I would like to get a surge valve to fit that existing hole. Can you recommend a good one that will fit. I just want to recirculate some of the pressure from the discharge tube back into the intake after the MAF sensor. BTW, I also vented the discharge directly to the atmosphere with no restrcition and it seemed to sound very "cammy". I think maybe it was rich? i don't know, but it sounded real good and it didn't surge when i vented directly to atmosphere at idle. weird. only surges when i re-circ the air./ Thanks oh yeah, he also said that it should increase my drivability around town/