More exhaust questions

[SuperBuickGuy]

At the risk of Chad thinking this is dumb, I've got another question about exhaust.
I like the sidepipes, no, I LOVE the sidepipes on my Corvette and I'll not be shut of them. However, there's a choice - either quiet, restrictive inserts, or "I can hear you a mile away" dynomax inserts.... there's got to be a midpoint

No one, that I've found, has cut apart a Chambered Hooker insert - until now. I haven't decided what I'm going to do... so that's going to be the question.... Dynomax inserts are merely cherry bombs - same design, just a funnel into the insert on either end to prevent exhaust from going around the insert and to lower rattles.

OTH - chambered Hooker inserts are roundly criticized (rightly) for killing HP, you'll see why they do that in a second. That said, they are quiet - like turbo muffler quiet... too quiet IMO, but if I ever want my wife to ride with me in my Corvette - I need to do something about the 100 db noise..... In short, I want my cake and eat it too. I should be able to devise some way of lowering the restriction while still maintaining quiet.... perhaps something like the C6 Corvette's baffles that open?

anyway... pictures

[SuperBuickGuy]

if you're wondering when I'll show you the restriction... all exhaust has to flow through this wrap




so what to do? spring-loaded baffle? build a bypass valve?

I like the idea of a bypass valve - but the question becomes how to do it.....

[Barry Donovan]

I can't see without a flash on the objects. carbon black.

maybe a cat honeycomb?

[yellomalibu]

Remove the insulation/ wrap. Then it would appear you would have 2 car chemistry inserts in each sidepipe.
Perhaps put the insulation in another section where the exhaust doesn't have to flow through it, yet it could possibly absorb some harshness of the sound.

Try both suggestions if you have the patience.

I was just googling images for exhaust inserts (again) and found something previous searches haven't turned up. I like the concept, yet have no idea how they sound. They are wicked expensive, but with a bit of time and fabrication, you could make something similar. These are $189/pair. Not to toot my own horn, but they are also similar to one of the ideas I've come up with in my head as a way to make a muffler.

[STINEY]

Where we ride in the sand, there is a db limit, which is enforced by random checks.

So there has been LOTS of experimentation, exactly the kind you are performing. And VWs are by no means the only engines out there......tons of built V8s of all makes.

I've settled on these, after trying all kinds of various home-brewed ideas.

Supertrap stainless muffler. It has a 'glass wrapped core "muffler", in which the exhaust travels through a tube with holes punched in it (complete holes, not perforations) and the holey tube is wrapped with glass. Note the exhaust does NOT travel through the actual glass, it just absorbes sound waves. Then the typical sparkarrester plates are directly on the end of the 6-8" long "muffler.

Great sound, and quiet enough to pass a 92db at 3000 rpm on my 13-1 ratio stroked monster. Figure that my engine displaces the same (roughly) as 1/2 of yours - - but you would have two of these mufflers, one for each half, so the net effect should be very similar.


I tried to post a picture, could only manage this link. Check out part # ST-443-2217 half-way down on the right, its a cutaway view of what we run.

Perhaps build something similar in sidepipe fashion? Longer, with the guts and sparkies hidden inside?

https://www.pegasusautoracing.com/2009/099.pdf

edit: Oh, and by the way, we double the number of plates. Sound stays the same, backpressure falls way off.

[SuperBuickGuy]

great suggestions - but I want it all. I think using a baffle design like Dave suggests would be great if I could close the inner passage and force the exhaust through the smaller holes on demand. Loud when I want it, and quiet when it's required.... if I could open the center of the core with something like this

yet, when closed, it could bypass around the outside - that would be ideal. The biggest problem I see so far is how to assemble it in the side pipe

Stiney - the problem with Super trapp baffles is how do you change the plates? I want to preserve the look of the 4" exhaust, so welding it to the end as curb feelers doesn't really float my boat - but trying to thread screws in the end of muffler, all while blind since you'd be doing it around the corner in the exhaust pipe doesn't sound like a good time... not to mention, imagine driving along, seeing a cop (while being too noisy), pulling over, whipping out some plates and installing them in the hot pipes.... not exactly my idea of a good time (but I don't do sand in the summer, so perhaps it's something others enjoy?)

[STINEY]

Ah, I misunderstood - I didn't catch you wanted a switch-on-the-fly noise control system, all or nothing.

I was aiming for "acceptable compromise" territory. (which my idea definitely covers)

As to your question on changing the plates.....I didn't figure on changing them. Set it and forget it was my plan.....92db is nothing on the loudness scale. I bet you a bottle of rum that your wife's hair-dryer makes double that, easy. (just send the rum to the same address as the Doug Nash please)

Although if you wanted tuneablilty, cutting the "sweep" from the sidepipes and fabbing a clamp for it would work. Remove bend/sweep, change plates, replace bend. Plates invisible, sound changeable.

Supertraps on the ends of sidepipes, ouch. You're making my minds eye cringe......please say I don't give off that particular vibe of tacky....

[anotheridiot]

what if you just cut a hole in that end piece that has the 6 holes?

[Barry Donovan]

centering a noise reduction is just another noise.

its hilarious. A different horn to toot.

I helped change mufflers on the rig, biggest side pipes going really..

baffles offset in a stagger. noisy when new, needs the carbon layer to quiet.

the old school vette gets it the same. may have to earn the finale.

about as simple as it gets. Two cone like pieces on the ends, and offset baffles, staggered.

A most unique one I found was the square box baffle inside a round insynerator bullit muffler. I can do no packing it sucks and blows everywhere.

that ended up nice.
the major problem with real noise cancel is it uses the materials. that means droning on 16 gauge etc...most crap for baffling and muffler going today.
once and awhile a company goes an extra step. the stainless high flow cat, insynerator has quite a brick for a muffler.. thick hard.

it costs a little more.

being on solid lifters, there is mist likely going to be a crackle sounding like a leak, but its just the engine.
kinda like the back of a stubby exhaust of a prosche gt3 set to fire, the crackle, it never ends.
my own midget boxer has it..a leak sound little lightnings.
that can be made appealing, only hinting performance.

it does take work. I found chopping sound bluntly is the best.. but needs real steel.

[SuperBuickGuy]

what if you just cut a hole in that end piece that has the 6 holes?

There are two of them (blocks) so I'd have to knock both of them out... it's there that I'd put a moveable baffle

centering a noise reduction is just another noise.

its hilarious. A different horn to toot.

I helped change mufflers on the rig, biggest side pipes going really..

baffles offset in a stagger. noisy when new, needs the carbon layer to quiet.

the old school vette gets it the same. may have to earn the finale.

about as simple as it gets. Two cone like pieces on the ends, and offset baffles, staggered.

A most unique one I found was the square box baffle inside a round insynerator bullit muffler. I can do no packing it sucks and blows everywhere.

that ended up nice.

I like the idea

another choice might be to punch the centers out, then put them on a spring-loaded pivot - so when you mash the loud pedal, the pressure overcomes the spring and creates a flow-through design

[anotheridiot]

I cant copy pictures to save my life here. you know I meant the other side at least. Yeah, spring loaded or a lever with a cable like that exhaust cutout.

[Bob Holmes]

http://www.summitracing.com/parts/wlk-17156?seid=srese1&gclid=CN6Y4-banbcCFSHhQgodkTQAWg

You want a variation on this. ??

[SuperBuickGuy]

http://www.summitracing.com/parts/wl...FSHhQgodkTQAWg

You want a variation on this. ??

yes, but fit it inside the side pipe and allow me to open it manually..... it's the second bit that I'm having trouble with

[anotheridiot]

you can always cut a slot in the inside of the pipe and hook a cable to it like an old time gate, otherwise its a butterfly like a throttle plate of a carburetor with a bellcrank on top to hook the cable to. That would allow you to variate the opening.

[Scott Liggett]

My neighbor has a stock 74 corvette with factory side pipes. Its barely louder than the factory under car exhaust.

Your exhaust note is also determined by compression and cam timing. I have had the same mufflers on my car with three cams. Smaller to larger cam. The car got louder. So my neighbor's L48 powered, low compression, tiny cammed 350 with side pipes barely burbles.