PSE switch...part needed

[Kirk]

Gary,

I agree with your understanding that on a turbo car - the less the backpressure, the better... period. I think that a system like this could benefit you a lot. I know you're just doing it for the sound, but there's a potential for at least some performance improvement as well. I would not expect that on a normally aspirated car though.

I know Boggtown did the electric valves on his car. Personally I would lean towards vacuum operated valves though. With the electric valves you've either got them open, closed, or dink around with setting them partially open somewhere inbetween. I would think that with a vacuum operated valve though you could simply tie it to the vacuum side of the engine (intake) and let that control the valves. As your car generated more vacuum (higher revs) the valves would automatically open more, giving you more sound. When you came to a stop the valves would slam shut and the car would be quiet. You could still wire a solenoid in there to keep the valves closed if you wanted too based on an electric switch in the cabin. You could also put a manual boost controller (MBC) in-line and set it so that the valves only see vacuum and open after a certain vacuum level is reached (say above 3000 rpm, so there is no resonance). An MBC turned around 180 degrees is simply a vacuum control valve rather than a pressure control valve.

I see a huge number of advantages to going with a vacuum controlled valve as opposed to an electric valve. But maybe that is just my perspective. You see back when I owned a Subaru WRX I sold "Bristol Boost" control systems for their turbo (if you google this you can find my posts on the WRX boards regarding this mod). This system used solenoid valves and two MBCs to control a dual stage boost pressure system. It may seem complicated, but it's relatively easy using parts I made or modified.

Looking at the PSE system with vacuum valves I've been kicking around the idea of using my Bristol Boost type of control system on these kinds of valves for controlling exhaust noise. The result would be more noise, controlled by you, with NO resonance since you control the exact kick-over of the system.

Right now I'm waiting on a Gemballa exhaust for my car, which I should receive in a couple weeks. Once I've got that on the car I'll see how it sounds and I may look into a source for these vacuum controlled valves a little more to maybe modify that exhaust.

Just throwing out some more food for thought and giving you a glimpse of what I've been considering.

Kirk

[Gary in BR]

Kirk,

That is a great idea. Explain to me what the difference in your plan to what PSE offers? Does PSE bypass the muffler at all?

I would love to hear it if you install one on your car.

Having lived with straight pipes and loved a bypassed muffler I think for me having the complete control over the sound will suit me best.

If you where to develop a muffler system for the Boxster that you mentioned I am sure there is a market for it and it would be very profitable.

Keep me updated in this idea.

[Kirk]

Gary,

Glad you like some of my ideas. My understanding of the PSE (Porsche Sport Exhaust) is that it has cut out valves just like you're planning to install. The only difference is that theirs are vacuum controlled rather than electric. Exactly how the PSE valves are controlled though I do not know. I think there's some kind of electronic wizardry that they use in the control. The PSE does bypass the muffler when engaged.

The intake on an engine though has vacuum. As the pistons move down the intake valves open and the pistons suck in fresh air and gasoline. Theoretically I don't think you need a lot of electronic wizardry with vacuum controlled valves then. Just hook them up to your intake vacuum and they'll open more as you increase revs and thus give you more sound and maybe more power...

My gut feel too is that vacuum valves are more robust than electric ones. The wastegate on a turbo is basically the same as a vacuum valve, except it works off of boost pressure. They are made to withstand very high exhaust temperatures.

Since you've got a turbo car you really might want to give sharkwerks a call and see if they can hook you up with a couple of their valves.

http://www.sharkwerks.com/products.php?pid=153

They gave me the name of the company that makes their valves, but I don't have it at home right now. This company that makes the valves though had a turbo boost pressure controlled bypass valve (like a wastegate valve). That might be just the ticket for you! Imagine that - just run a hose from the boost side of your turbos to the bypass valves. As you get more boost pressure, then you use a little bit of that pressure to push the valves open.

[Kirk]

Here ya go Gary, a boost activated exhaust bypass valve:

http://www.atpturbo.com/root/releases/release091004.htm

This is exactly what you need! IMHO

Only problem is that the last time I talked to this company they said their valves are backordered and have been for months... That pretty much means they're unavailable. But someone else has to sell the same kind of thing.

To activate these I would just put a T connection in the line going to your turbo's wastegate valve. The air bubbler T connections used in fish tanks would work (as long as it's not in a high heat area), or you can buy T connections at any auto parts store. Then I'd run the hose from this T connection to the two bypass valves. If you want to control when they see the boost pressure, just put an MBC in-line with the hose. If you want a really cheap and simple MBC I can make you one. You could also put a solenoid valve in-line to turn the valves on and off. I used to source one from Car Quest. I'll have to see if I can dig up the part number.

Too bad I live in California. I'd love to work with you on this project directly.

[Gary in BR]

This has been in the front of my mind all week.

Tonights project is investigating the boost controlled valves.

I can see where there may be a few advantages, mainly the valves going full open under wide open throttle without me having to hit a button first.

Research will start tonight.
Kirk if you have an links I should visit let me know.


Thanks.

[blinkwatt]

Originally Posted by Kirk

I would think that with a vacuum operated valve though you could simply tie it to the vacuum side of the engine (intake) and let that control the valves. As your car generated more vacuum (higher revs) the valves would automatically open more, giving you more sound. When you came to a stop the valves would slam shut and the car would be quiet.

How do you tie into the vacuum?