twinkletoes

iTrader: (17)

Ya, my friend will do that if he revs up. He'll do it in parking garages and set off about 5 cars off or more. It's pretty funny.

OtakuRX

iTrader: (1)

I know the feeling and it is great, tho I plan on putting on a 3rd muffler soon. it is amazing how loud this cars get with no cat and 2.5" exhaust.

slayerx7

iTrader: (4)

Oh yes indeed it is! I straight piped my header all the way back. At Schucks Check or Kragen (depending where your located) I found a raptor muffler for $25 its pretty light. Slapped that at the end of the straight pipe, and its definately louder than stock, but not enough to wake up the neighbors under 3 grand. Over 3 grand is a different story.

I wish I could fabricate my own parts!!

The thing to realize about us 'light car people' is the philosophy 'Worry about the ounces and the pounds will follow' If anyone thinks Im **** about keeping a lightweight car, you should see my bike! HOWEVER SPANDEX IS NOT AN OPTION!!!!

Bruceman

iTrader: (5)

I'm sure it will sound good.
I've built a few using stainless steel fire extinguishers with the steel wool and high temp insulation.
And don't forget the custom exhaust tip.

Blk82GSL

Man, some websites really annoy me. I got NO email responses past the initial few, when I was still responding. The last time I replied, I got nothing else...Sorry guys, not your fault.......

Update!!:

Whew, finally scraped up the cash for the RB header and Bonez universal Cat. 5 or so days for all shipping, and a day off so I can tow it in to a shop. Gotta tow it, hehe. I don't think I would make it very far with an open header, the cops would be all over me, haha. I'm bolting the header on, since no local shop will do it for legal reasons. I imagine they can fab the remainder without fear of lawyers. At least I hope they can. Otherwise I will have to make the parts from straight tubing as patterns, and have them bent at a shop. That would be a huge PITA, lol.

perfect_circle

i cant wait

Blk82GSL

Well, been way too long, and for that I apologize. I have to make the mount for the rear of the muffler, maybe front too once I cut out the original. Oh well, here's the latest pic. The parts on the driveway to drool over, lol.

trochoid

iTrader: (6)

Keep us posted on the long term results. It's great to see this kind of ingenuity and thought put into a money saving project. Keep at it.

Fyi, you will probably be disappointed in the BD louvers, even if you buy the aluminum ones. The plastic ones look,..........well,............ like plastic. None of the newer ones look as good as the old school ones.

ray green

iTrader: (14)

That's neat!

Ray

Scott1982

Awesome job, you going in the business?
Scott

purple82

Doing stuff by yourself is a satisfying and cost saving exercise and I applaud your effort. But mufflers are designed for wavelength cancellation both by the size of the passages and the size and shape of the chambers. To do it right, you need pretty decent knowledge of acoustics and waveform behavior, some fairly expensive simulation tools and a pretty good prototype budget to do testing.

I hope your muffler works out great. But don't be surprised if you find a couple of engine speeds that drone so badly that you can't spend any time there. Even if the exhaust is quiet enough in general. The flat walls on your design may actually amplify some frequencies. Hopefully it's just not in any RPM where you typically cruise.

rx_n

My only comment is that steel wool burns like crazy and continutes to burn until every last bit of it is gone. Take a lighter to a piece of loosened steel wool and you will see what I mean, especially the softer steel wool. It may not be too much of a fire hazzard since it is contained in the muffler housing, but you may loose your muffling effect. Let us know how it goes..

Blk82GSL

The RB muffler is pretty much a straight through glasspack with SS wool? What did they do, but build the same thing I did, but round? I also started the engine up with only the factory cat, and the rest of the exhaust cut off. It was barely louder than stock. What the muffler would actually have to do to be annoying and droney, I have no idea. And I am using SS wool btw, not steel wool. Steel wool would overheat and break down, eventually to be blown out the tailpipe. I knew that. It cost $150, if it lasts 3-5 years I'll have got way more than my money's worth out of it, and will build another once that happens.

steve84GS TII

Heh,heh.....still waiting with baited breath to hear that thing purr!

Ill have to get a sound clip of my RB SP, and post it up when you get yours running,so we can do a side-by-side comparo of the two.

Blk82GSL

Gonna have to wait till next week, unless I can get the broken exhaust stud drilled and heli coiled, the header bolted up, and rent a dolly, and get the exhaust all built up tomorrow. I work Wed/Thur/Fri every week.

1badFB

iTrader: (1)

http://www.rx7club.com/attachment.ph...hmentid=200537

Bruceman, that is a sick muffler tip. Thats really got me thinkin..

You wouldnt wanna make any more of those would you?

Nicholas P.

iTrader: (1)

I cant wait to hear what it sounds like.

purple82

Internal pipe lengths, hole sizes and chamber sizes are all chosen to cancel the right frequencies. If the dimensions aren't right, you'll ADD drone over a system with no muffler. Like I said, I hope it works out, but there's a reason these things are more than just the cost of parts.

Blk82GSL

Yeah I know. You have to spread gloom and doom because you have to feel good about spending all that money right? Same thing I have found in the bicycle world. Road bike snobs are worse than anything. I said this was an experiment. If it doesn't work out, then it doesn't. Save your gloomy attitude, please!

Nicholas P.

iTrader: (1)

Your doing the same thing a physicist does. Build and ask questions, maybe even finding out a better way.

He could make a perfect muffler, why critize his motivation?

13BT_RX3

I had a 13B bridgeport on the street for 8 years or so. I went through a lot of exhaust parts. There are not too many products that are worth a damn and there were even less back then. Because of the weak aftemarket support I decided to experiment with making a few mufflers.

The problems with most muffler available.. Fiberglass packing was then number 1 shortcoming of most muffers. Number 2 was the lack of thick wall casings. Number 3 was flat oval V8 style muffler cases being the standard. The flat side would become a speaker at the resonance frequency. Usually right at freeway speed.

Thick cased round to roundish mufflers will help keep the noise out of the cockpit. On a straight through muffler more internal packing area and more tube perforation area = more quiet.

I once used a catylitic converter casing to make a presilencer with stainless steel scouring pads and a piece of 16ga tubing. I drill a lot of holes in it and realized too late how much work that was. Afterwards I decided it is best to get tubes pre-perforated or roll a perforated sheet. This will probably give more open area than a hand drilled tube.

The result... No more worries about police ticketing me for an emissions equipment violation. No I have a cat...see. No added cockpit noise. No noticable loss in power. Slight reduction in sound level. I atributed this to not enough perforations.

I think your muffler has promise and I look forward to hearing how it works for you.

Blk82GSL

It isn't going to work at all, until the engine gets a new rear rotor housing. Damn stud broke off, so it's all over. Maybe after the first of the year, I might have eenough to pay someone to do it. But for now, it's on permanent back burner status. Oh well.

purple82

I'm an engineer. I design systems that require passing stringent acoustic regulations. I have knowledge in how to design for such requirements. I'm explainig to you how these things work and what to expect and why. If you somehow took this as criticism, that isn't my intent.

If you only want to hear "great job" and "good for you" maybe you're posting in the wrong place.

Blk82GSL

God you're obstinate. Engine needs rebuilt due to a broken/stuck exhaust stud, and you're still piling it on. Thanks a bunch dude, you really made my day. So in a way, you got your wish, the car will not be going anywhere for quite a while with this droning overly loud acoustically inefficient home made muffler.

purple82

My wish? I'm not sure what you mean or how in any way indicated that I didn't want your car to run. Good luck.