Dual SAAB/Porsche BOVs

[thelonerider]

I just picked up a HKS 3000 pipe and was thinking of running dual BOV...

Why?

I'm running a 62-1 upgrade and I want to make sure enough pressure is released so to protect the Turbo.

The BOV are faily cheap and I already have one.
I can drill and tap some fittings into my aluminum IC pipes just infront of the HKS to allow for a BOV.
No flange or additional joint in the IC.

I know someone has done it as I remember seeing a pic of an engine bay with dual BOV.

So....
Does anyone know who that was?
What are your thoughts on this? Please keep it technical and not post an opinion or your "feelings"
Would this be pointless as both BOV would be trying to recurculate through the same small hole in the accordion hose.?
Alternatives in the same price range (~$100)?

 

[trydrew]

Adjuster: http://www.supramania.com/forums/showpost.php?p=882583&postcount=354
I'm sure he'd be happy to explain why he doing so as his build it so thorough, and everything has a reason. lol

 

[thelonerider]

BUMP
Hmmm, not to much technical feedback on using 2 Porsche BOV....
OK, opinions are welcome now... but keep it on topic, please...

 

[Piratetip]

As long as you have 2 working valves that don't leak this would be a good idea.
Just a second controlled boost leak.
As you said, just to be sure you don't have surging.
Do it.

 

[j3pz]

not exactly what your looking for but...
http://www.supramania.com/forums/showpost.php?p=439334&postcount=121

 

[mkIIIman089]

Unless you are hearing abnormal noises (compressor surge) when the BOV is releasing air, I wouldn't worry about it.

If you were going to run 2 Porsche valves, as you already know, to get the best out of them you should have another port in your intake hose to make sure when they go off, it doesn't just jam up after the valve.

 

[Adjuster]

Someone pointed out this post, so I figure I'd better get in here and clarify why I did two Bosch Bypass Valves. (Porsche spec, with the stronger springs.)

The Bosch Bypass Valve is designed to be pulled slightly open under vac conditions, and then close up as the pressure goes from vac to zero to under pressure.

They also hold up well, and do not "leak" when installed the right way in my use of these valves for many years now. (The right way being the way I have mine hooked up. There are some who say mine are bass akwards, and either way they leak, but I don't agree.)

With just one valve, you can play a tune of sorts. They tend to hoot, and make noise as the valve opens and closes slowly. This is from air rushing past the slightly open valve diaphram I'm guessing.

With my setup, there is a distinct shortcut for the filtered air to go right around the turbo, FMIC and IC pipes. This shortcut improves low end throttle response, while the engine is not boosting under pressure.

As the pressure builds up, the valve closes up tight, since there is not a "Vac" signal anymore.. also any large body of air pressure is trying to push open the valve, and the rubber diaphram can't go that way, so it actually seals up the valve tighter under high boost use. (Sure, there is also pressure on the vac line side, but not as much volume, so even if the pressure is equal, the spring pressure of the valve will keep it shut, my thought is that the larger 1" port side has faster reaction time to pressure changes than the smaller vac lines, so plumbed this way, the valve is held shut better than if they are backwards, and yet, there is still plenty of vac signal to pull the valves open between shifts for example.)

Compressor surge is the enemy, and these valves do a great job bypassing the air pressure spike back into the intake, where you can use that pressure to help keep the turbine at a higher shaft speed during times when you back off the throttle to shift for example.

Mine is not only set to release the air pressure spike, but direct it back, so it blows air over/into the compressor wheel.. Further keeping it spooled up better under any time when there is excess boost pressure in the IC pipes.

Here are a few photos of the current setup. Note the custom air intake between the filter and the turbo inlet have two angled 1" ID fittings. These allow the valves to direct the air at the turbo, and actually get it swirling up if I designe them correctly.... They are just welded to the 4" intake pipe. The upper IC pipe is 3" ID, and has two more 1" ID fittings welded to the pipe. Might as well not lose any mechanical energy right?

 

[Adrian98]

I've seen the setup with the BOVs being on each side of large FMICs

 

[thelonerider]

Thanks for the input, Adjuster.
So, two inputs would be needed on the accordian hose for this to work properly.
I've seen some really cheap IC flange options on ebay, priced around $10 (some with absurd shipping cost) as well as BOV in the < $30 price but don't know what the rep is on these.. you get what you pay for, right? It would also require me to add another set of couplers to include the pipe in the IC which I want to avoid.