DIY exhaust valves?

[geraintthomas]

Something that I'm thinking of doing. Started talking to Meir about it in another thread, but thought I'd make one here.

I've got exhaust bypass pipes on my stock muffler which give an incredible sound. These are the pipes:



As you can see, it connect just after the CATS and straight into the tailpipes. I'm considering the possibilities of adding valves so that I can control whether it's on or off.

The electrical side is easy (relatively speaking). Just have to get a 996 exhaust switch, use a latching relay so that on and off can be one-touch rather than holding the button. It's the valves that I'm trying to get my head around.

There's two potential ways:


Electrical exhaust valves



If there were such a thing as 1" electronic cut-outs that you could buy with motorised valves, then that would be easy. Wire them up to the dash switch with a relay, bobs your uncle. But every electric exhaust cut-out valve I've seen are 2.5" and up. This would be far too big. Are there any that are around 1"?


Vacuum exhaust valves



The other option is to install vacuum valves with a vacuum solenoid to control them, like an OEM setup. I could source the valves off another car that could be around the correct size, then wire the switch up to a vacuum solenoid. The solenoid is (apparently) the little box that directs the vacuum to the valves when receiving a 12v current, and stops doing so if it doesn't get any. In other words, opening and closing the valve with the current received from a switch.

But my question for the vacuum setup is this - where on earth do I get a vacuum feed on a Boxster? Also, could someone explain how the solenoids are connected up? They have an electrical connector (for the switch), but 3 vacuum nipples? This is a guess, but are there two for the vacuum to pass through the solenoid, and one for going to the exhaust valve?

Any help would be appreciated. Thanks!

[Ben006]

Vacuum is a better idea.
The exhaust is vibrating a lot, and electromechnical stuffs don't like that :/

Were to get vacuum from? Easy, there are a million vacuum hoses on our engine! or at least that's what it looks like when I'm working on one... ^^
Just use a T fitting on an existing vacuum line and you're set!

The third fitting is a venting port. If you apply vacuum to something, but then you just close the line, vacuum is still present, and the solenoid is not doing anything. You need a vent to get atmospheric pressure back in.

[geraintthomas]

OH!

So, something like this?



So it'll be a case of locating a vacuum pipe, cutting it, putting a T-junction on it and connecting it like the above?

[Ben006]

Yes, exactly!

[geraintthomas]

Problem is that, with a vacuum setup, the car won't 'remember' the setting.

Sometimes I may want it to be open on startup to get that awesome start sound, but sometimes I may want it quiet. There's no way to turn it on or off before the engine has started due to them needing a vacuum

Bit of a hard one this.

[The Radium King]

depends on how you want it to function. vacuum are (a) faster, and (b) good for a lot more operations before they die. if you just want if on sometimes, off sometimes, then electrical will work fine.

if you want it to work like porsche oem you want vacuum. here's why - the porsche units activate with every blip of the throttle - cruising at 3k rpm - valves closed. rpm gets over 4500 or so (ie, you are hard on it) then valves open up (better sound, less back pressure for better performance). so, you need them to work fast, and you seen something that is good for hundreds of thousands of operations.

wiring is easy either way. electric is power and a switch. vacuum is easy too. your car already has a vacuum system. one of the vacuum actuated things on the car is the flapper valve on the resonance tube - it actuates at around 4500 rpm (can't remember the exact value) - the exact thing you need for the exhaust (and for the same reasons, btw). the vacuum system on the car feeds into a electrically-actuated vacuum switch, where the ecu sends the open/close signal. so, you can tap off the vacuum line that is feeding the resonance flapper so that your exhaust goes when the flapper goes, or you can get a second vacuum switch and tap off the ecu signal going to the resonance flapper. the benefit of the second approach is that you can put a switch on it so that you can turn off the exhaust if you like.

seach 'cut out' on ebay - most folks just put a cut-on on their exhaust to bypass the muffler altogether, so that is how the pruducts are marketed.

[geraintthomas]

Originally Posted by The Radium King

depends on how you want it to function. vacuum are (a) faster, and (b) good for a lot more operations before they die. if you just want if on sometimes, off sometimes, then electrical will work fine.

if you want it to work like porsche oem you want vacuum. here's why - the porsche units activate with every blip of the throttle - cruising at 3k rpm - valves closed. rpm gets over 4500 or so (ie, you are hard on it) then valves open up (better sound, less back pressure for better performance). so, you need them to work fast, and you seen something that is good for hundreds of thousands of operations.

wiring is easy either way. electric is power and a switch. vacuum is easy too. your car already has a vacuum system. one of the vacuum actuated things on the car is the flapper valve on the resonance tube - it actuates at around 4500 rpm (can't remember the exact value) - the exact thing you need for the exhaust (and for the same reasons, btw). the vacuum system on the car feeds into a electrically-actuated vacuum switch, where the ecu sends the open/close signal. so, you can tap off the vacuum line that is feeding the resonance flapper so that your exhaust goes when the flapper goes, or you can get a second vacuum switch and tap off the ecu signal going to the resonance flapper. the benefit of the second approach is that you can put a switch on it so that you can turn off the exhaust if you like.

seach 'cut out' on ebay - most folks just put a cut-on on their exhaust to bypass the muffler altogether, so that is how the pruducts are marketed.

Great stuff. The only issue with this is that the exhausts are never fully on, and require throttle for the valves to open up. My desire is to have them act like electric ones. Open or closed, and they stay open or closed until I decide otherwise. I think it may be too hard to do this with a vacuum system.

But it's finding an electrical valve that's around 1" size. It seems impossible, because space is quite tight as you can see from the photo.

[Ben006]

With Meir's latching relay you can control a solenoid and you'll have the "memory"

[Meir]

Since you are on the right side of the pond, order yourself on of Durite 12V 25 Amp Latching Relay - Changeover 5 Pin 0-728-02 | eBay
It's a mechanic latch relay, so the power consumption is momentary and the solenoid valve will always keep its last position. The only problem you might have, as at the initial startup, that valve might be open for few seconds until the vacuum builds up.
I'm talking out of logic only, as I didn't get a chance to test it yet.
As for the vacuum supply line, do not cut anything. Look for existing connection, replace it with a Y and another Y to split to each valve.
I'll try to see if I can find a pic for you.

[Meir]

this is the vacuum system diagram.



you need to locate one of the parts marked 19, and replace it with part 21.
then you use another 21 to split the line into the two valves, thru the solenoid.
obviously you need to buy part 21 not use the one you have on the car



edit: excuse the typo on the solenoid

[The Radium King]

just get a 2" electric cut out kit off ebay. they come with y-pipes so you can just cut it into your 2" exhaust between your cat and the u-pipe. the dump is flanged for the valve and you can put a reducer on the output of the vave to tie it in with your 1" to the tips.

http://www.ebay.com/itm/Dyno-2-Electric-Stainless-Exhaust-Cutout-Cut-Out-Dump-Valve-switch-with-Remote-/151940607385?hash=item23605dad99:g:LtMAAOSw5dNWjNT d&vxp=mtr

[particlewave]

Yeah, I agree. Vacuum is a PITA. You'll just be inviting more leaks (ever try to track down a vacuum leak?) and vacuum valves have their own sets of issues. Not to mention that loss of vacuum affects the engine directly.
Electric actually isn't bothered by the heat or vibration if done right, is smaller and is easier to diagnose if there is an issue. You already have to run electric for the vacuum actuator valve, so it would be easier to just ditch the vacuum idea.

[10/10ths]

....lived through the 70's.

No vacuum.

Please, I don't ever want anything vacuum operated ever again.

Just stop.

Please.

Don't.

Be afraid.


Be VERY afraid.

[Meir]

you can also go with the more relaieble version AKA PHDE (Porsche Home Depot Exhaust)

[Anker]

About 8 lbs of iron on each side! But a neat solution.

[RedBeauty]

Just wanted to check if there is any progress / solution here. Ive done the bypass 1,25 inch pipe. Love it at start up, love it over 3000 rpm and when i drive it like a racer, but hate it betwen 2-3k rpm and evryday slow driving. Its just too mouch. now i concider to re do it to 1" or eaven 0,75" to make it more correct volume vise to the actual engine. Anyways i would like a 1" valve that is elecrical and have searched the internet up and down! As mentioned the problem is spacing, and i originaly bought a 2" electrical valve that i just could not fit in