Valved Exhausts

[V AR 164]

Hi all,

Recently on hard rubbish, I picked up a pair of rear Bi-Modal mufflers that came off of an E2 or E3 HSV. These mufflers have a small vacuum controlled solenoid that when vacuum is applied, the valve shuts and causes exhaust gasses to travel through the muffler therefore making it quiet. But when no vacuum is present, the valves are open and it is in 'loud' mode.

I'm just playing with the idea of mocking one up on my 164q and having a switch that enables me to choose between loud and quiet. Right now I have a stainless magnaflow rear muffler with a full header back system and it can get pretty loud... Plus I've got some stainless headers which will go on soon and I feel as though it will be obnoxious.

I believe a member on here has done something similar on his 164 (can't remember who it was) and just looking for some ideas on how to go about creating a vacuum system in the back of the car. I was thinking of a small air pump, but I would assume that would get pretty annoying hearing that all the time. Do I just run a vacuum line off the intake all the way to the rear and have an electronic air valve in the middle?

Obviously one will need some modification to fit but I thought its a pretty neat idea.

Any suggestions?
Thanks, Andrew.

[Citroënbender]

You could use the Hella-built vacuum pump off almost any '90s Eurotrash cruise control.

Example for basically how they look, BMW, Pug/Citroën, SAAB, Volvo all used them: https://www.ebay.com.au/itm/192547537687

I kind of like quiet cars, but that's just me!

[V AR 164]

Thanks for that CB good recommendation, although I think $150ish is a tad steep. I'll keep an eye out online or even at the wreckers for something similar.

Well, being a 'typical teenager' my cars tend to be on the very loud side... I was told by my dad he could hear me shift through all the gears whilst merging on freeway on-ramp the other afternoon. Mind you it is just short of 1 km down the road and I wasn't even going for it...

Andrew.

[Citroënbender]

Absolutely hit the wreckers, I wouldn't pay $150 either! Mount it with those little back-to-back rubber isolators that have an M5 or M6 thread both sides.

This one is cheap, probably a Denso:
https://www.ebay.com.au/itm/282006824446

Edit to note, the only time I relish a loud exhaust is when I'm too far past the RBT for them to entertain waving me in, or chasing me on a whim. 

[Duk]

Do I just run a vacuum line off the intake all the way to the rear and have an electronic air valve in the middle?

That'd be what I would do, but add a 1 way/check valve near the inlet manifold and use either use fairly large diameter hose (6mm/0.25" size) or a small tank in the boot to act as a reservoir. That should allow the valve to act in a much more consistent manor if you expect it to activate a few times quickly with a low manifold vacuum for what ever reason.

[V AR 164]

Mocked the muffler up today and temporary connected it and started the car. Sounds a lot quieter even with the valve open, I closed it and it sounded factory like. Definitely much quieter than my current setup.

Pulled a vacuum line off the intake and connected the muffler solenoid with a silicon vacuum line and the flap worked perfectly. I may end up running a line from the front to the back. Using a steel tube is a good idea as well, I could tuck it up next to the fuel lines.

I'll keep everyone updated with my progress.

Andrew.

[ARQ164 Shane]

Hi Andrew mate
wow twins, with plumbing   
Lots of great ideas that awesome this as my 2 cents back in the day corvettes had vacuum head light where
ran a line from the inlet manifolded with an value not shore if that helps ?

good luck mate 

[poohbah]

Andrew, did I read you right - you found these on someone's verge, for rubbish collection?

I'd be marking their address down and then drive by every few weeks to see what other "rubbish" they don't want.

[V AR 164]

Yes you did, I couldn't believe it either! You would be surprised what some people throw out, one year I saw a full set of alloy wheels!!! Don't remember what car they came off though.

[poohbah]

Great find. Definitely do something with them. Surprising that they are quieter than your existing set up with valves open. Have you deleted a muffler already?