Switchable Exhaust | 70s 911

[Pork Chops]

You know. It's loud and throaty and then you hit a button and it's all tame and quiet.

Any idea of how this could be done? Done it before yourself? Know someone who sells a kit? I've got some ideas but yours are most welcome too.

Cheers.

[Jack Olsen]

There are manual and electric exhaust cut-outs.

[Pork Chops]

Originally Posted by Jack Olsen

There are manual and electric exhaust cut-outs.

Thanks Jack. You mean something like this? What switches? Electric? Mechanical? Located where? I'm concerned they may not last long so close to the headers, and especially if electric.

Any pics of a system, or details of components or layouts?

Cheers.

[kghjr]

I had this set up on a straight six, a linear actuator on a butterfly valve.

I put the Ranchero on a dyno and it lost HP with the open pipe and reduced back pressure, but it sounded really cool, with the cut-out emptying out under the truck bed. It can be opened a little or all the way.

Highly illegal in all states.

[RarlyL8]

We're actually working on one right now. Packaging and keeping the cost down are the sticking points. Forget using aluminum or electric valves. I've been testing valves for 10 years to find one that does what we and will live more than a couple months. The vast majority of stuff out there is pure junk, toys for those who don't drive their cars much.

[evan9eleven]

I built a system like this for my Boxster, using vacuum-actuated valves ($$) to open up a partial bypass. Its been working fine for a couple years now, and I am going to make another version at some point that is louder when open. I have considered making a system for my SC, but mostly I'm happy with it just being loud all the time.

[Trackrash]

Exhaust Cutouts | JEGS

[RSTarga]

Why not just do a 3 outlet sport muffler and put caps on the sport tubes when you want quiet. Takes about 2 minutes to put the caps on.
I think Sycip makes this conversion on A dansk SS muffler.

[Jack Olsen]

Probably not what you're looking for, but here's the cheapest option: dual outlet exhaust (with common chamber) made quiet (and with far less resonance) with a cap made out of a Campbell's soup can -- black hole painted on it for Roadrunner-and-Coyote-style illusion of an opening.

[Saadi996tt]

That's so simple it's genius!


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[81SC]

[ALEX P]

These are switchable (as image above). They're not cheap though!!

BS Motorsport

[Jack Olsen]

Originally Posted by Saadi996tt

That's so simple it's genius!

I don't know about genius. But it does cost less than a buck -- and it comes with a free bowl of soup.

[bkreigsr]

Originally Posted by Jack Olsen

Probably not what you're looking for, but here's the cheapest option: dual outlet exhaust (with common chamber) made quiet (and with far less resonance) with a cap made out of a Campbell's soup can -- black hole painted on it for Roadrunner-and-Coyote-style illusion of an opening.

wait a minute...wait a minute
Isn't this the same guy that used a rattle-can cap to replace a 'RS' style taillight lens when he caught a tire wall at Willow Springs??

Bill K

[Jack Olsen]

That's me. I hit the tire wall at Sears Point, and had to find a way to drive legally down to Los Angeles for a visit to Willow Springs the next day. Two were still intact, but two got the low-cost, highway-patrol-friendly fix.



Not bad, considering how it looked the day before:

[Tremelune]

Hilarious solutions. I once printed headlight graphics out and taped them to my fiberglass front to get home...



Doesn't the air/fuel mixture change when you simply stuff up one exhaust outlet?

One issue with having several mufflers on these cars is that the oil tank gets in the way on the right side of the car. Left side is pretty clear, and I have half a mind to stuff half a 993 muffler in my own car.

I've seen a couple GT3 mufflers on old 911s, and I believe they have a multiple-path system...

[Jack Olsen]

Originally Posted by Tremelune

Hilarious solutions. I once printed headlight graphics out and taped them to my fiberglass front to get home...



Doesn't the air/fuel mixture change when you simply stuff up one exhaust outlet?

One issue with having several mufflers on these cars is that the oil tank gets in the way on the right side of the car. Left side is pretty clear, and I have half a mind to stuff half a 993 muffler in my own car.

I've seen a couple GT3 mufflers on old 911s, and I believe they have a multiple-path system...

I added the cap to reduce resonance, not really to reduce overall volume (although it did that, to some extent). If the outlets were discreet from one another in any way, I wouldn't have done this. But they're essentially just two exit doors from the same room. I can't imagine how air/fuel ratios could be affected so far downstream of the engine.

Ultimately, I dumped the Flowmaster muffler altogether and changed to a Magnaflow, which has no resonance and sounds better. So, no more cap.

Those headlights look great, by the way. If I were a man in blue, I'd believe it.

[Saadi996tt]

Originally Posted by Jack Olsen

I don't know about genius. But it does cost less than a buck -- and it comes with a free bowl of soup.

And if you don't like the looks or performance you can sell it for .5 cents to the local recycler. No need to post on pelican classifieds



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[Pork Chops]

Hilarious and helpful stuff. Thanks guys. Jack love the can and yes that's the fall back solution if it all gets too hard / expensive. There is a chap in NZ who has done a switchable system in his 964 using a GT3 muffler which I'll see later in the month, and there is a thread here DDK - Die Deutschen Klassiker • View topic - RSR exhaust box (which I'm yet to read) from 81SC above. Monty from Monty's Mufflers is going to have a crack at designing something for me (he's local to me) so be interesting to see what he comes up with.

Cheers.