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PostPosted: Sat Jul 11, 2015 7:37 pm 
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I like your new avatar picture Cliff. Pretty racy.

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PostPosted: Sat Jul 11, 2015 9:40 pm 
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And congratulations on un-suspending yourself. I am sure it was difficult, but someone had to do it.

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PostPosted: Tue Jul 28, 2015 10:22 pm 
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Anyone tried that Italian made aluminum muffler? Very light.

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PostPosted: Tue Jul 28, 2015 10:42 pm 
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I would hesitate to use an aluminum muffler where there is so much vibration.

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PostPosted: Wed Jul 29, 2015 9:11 pm 
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C J Murray wrote:
I would hesitate to use an aluminum muffler where there is so much vibration.


Cliff, because it will crack at the welds? Do airplanes only use rivets to join aluminum?

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PostPosted: Thu Jul 30, 2015 7:30 am 
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I'm not an engineer but an airplane is a monocoque structure that uses the method of construction and design to create something that is much stronger than it's individual components. I think the key is to spread out the stress throughout the entire structure.

Motorcycles have used aluminum mufflers but with mixed results AND I can't remember any street motorcycle system with aluminum pipes. You would need stainless pipes, somehow, attached to an aluminum muffler body, most likely with a pair of stainless end caps on the muffler. The problem is this, the heat and vibration make quick work of destroying the aluminum at the stress points such as where the pipes enter the muffler body. Our engines expand sideways causing stress. Our #2 and 4 pipes hold most of the muffler weight and need to be very strong. You MIGHT have better luck using an aluminum muffler on a Euro exhaust car where the muffler body is securely mounted to the engine brackets, maybe. On the standard type heater exhaust, you could create 2 steel muffler ends, each of which form the pipe connections to one or the other sides of the engine with a somewhat shorter center muffler can made of aluminum so that you would have a large aluminum can suspended between two steel structural members comprised of the exhaust inlet pipes. Unnecessary complication. Stainless makes more sense.

Anybody that has raced knows why I constructed this exhaust this way...

vibration never sleeps
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PostPosted: Thu Jul 30, 2015 6:30 pm 
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Commercially made race exhaust from the 70s.


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PostPosted: Thu Jul 30, 2015 7:31 pm 
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Jim, I'm guessing that muffler was removed for racing and maybe a megaphone or straight stinger was used for racing??? The aluminum muffler pictured looks like a typical aftermarket motorcycle muffler from back in the day. The steel pipes(stepped) and collector look good but without spring mounting I suspect it would crack in race use. I wonder how that worked on the dyno compared to ?????

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PostPosted: Fri Jul 31, 2015 12:46 am 
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My reading of the extraction design issues and muffler associated support issues indicates that the volume of the muffler should be larger to be beneficial. What do I know, I'm just relating what I've read. Do your own investigation, but from what I see in your exhaust tubings assembly, the header system is designed to maximize horsepower at higher RPMs. If that is what you want, find a muffler that will accommodate your intentions. I suspect that little twit is not helping your reach your goals. Only a real dyno testing routine will help your resolve the truths you're are seeking.


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PostPosted: Fri Jul 31, 2015 8:42 am 
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Glen, not sure which system you are referring to but I'll guess. The aluminum muffler(twit?) on Jim's system probably has a giant straight through hole with a small amount of fiberglass matt surrounding the hole and held with steel screen that does little to reduce sound. It probably doesn't hurt performance too much but it doesn't help. A megaphone or a megaphone with reverse cone, done correctly, has a very favorable effect to power. The 4 into 1 collector is beneficial if designed correctly or a 4 into 2 into 1, like a Bursch, might get the result that you want. They won't get the exact same result. Stepped head pipes, creating an internal anti-reversion effect is popular. Pipe diameter and length is very critical. Have fun on the dyno!

Street mufflers have a giant effect on how your car runs and Porsche spent some serious engineering effort on their mufflers which shows when you do dyno testing. Glen, you are correct, for a muffler to reduce noise AND make power it must be very large relative to engine displacement. Porsche went further with a very clever internal design that evened out the pipe lengths(front vs back) to get the best performance over the widest rpm range. Dansk has their fit issues but they make the muffler with the correct internals which is much more important. The fit issues can be dealt with. An empty can like other mufflers can't be corrected.

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PostPosted: Fri Jul 31, 2015 5:22 pm 
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In my 5 decades in General Aviation, and aircraft air cooled opposed piston engines, I've not seen anything but stainless mufflers.

Cliff, to accommodate engine heat generated expansion, in both directions, we had exhaust slip joints. We also had joint binding issues in high altitude turbocharged engine exhaust systems, followed by temperature differential cracking issues. The Lycoming service bulletin help for this, was to use Fel-Pro CA-5, a copper colored high temp anti-seize compound. I had to buy varying sizes of those muffler pipe expansion tools, to occasionally restore the shape back to round, and cone shaped tools to shrink the OD, to keep the close clearances needed to maintain the exhaust pressure to drive the turbo at altitude, a balancing act, but it did help to prevent the cracking.

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PostPosted: Fri Jul 31, 2015 6:04 pm 
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Hi Mike, stainless is really good at resisting cracks when faced with heat and vibration. I don't really know why but it works. I need some of that anti-seize for my racer. The stuff I've been using doesn't hold up to the heat and starts to gaul which defeats the function of the slip joints and the springs. Loosey goosey is what makes the whole thing survive the punishment. Aviation is the real home of high tech meets stone axe. You can't screw around with machines that could fall from the sky. I wish I had your knowledge. Thanks.

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Last edited by C J Murray on Sat Aug 22, 2015 2:39 pm, edited 1 time in total.

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PostPosted: Sat Aug 22, 2015 12:51 pm 
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How about the original quad pipe Abarths? Were they any good?

Any input would be much appreciated.

Thanks.

Jay

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PostPosted: Sun Aug 23, 2015 11:57 am 
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Ok, going to stick my neck way out here. Maybe ya could spend some time researching exhaust tubing design and come up with something of your own. I've always been amazed how many solutions have been developed over the years. When I started thinking on the possibilities I was hoping to move the weight of the muffler forward for better weight distribution. The Euro solution seemed to be an interesting approach. As I read and realized the routing of the exhaust tubing was a rather complex affair I came to realize that out back had values that were not readily apparent before I began studying the realities.

As stainless has a longer life than mild steel tubing, not all stainless is created equal, I resolved that stainless was a better material for a longer life.

I also wanted an exhaust system that would be as quiet as the muffler on our 911, I wan no longer wanting to listen to the rap of the exhaust that made me smile in my youth. Soooooo, how to obtains quiet but without the tinny sound emitted from a stock system.

Looking at the development of mufflers and horse power, quiet but still productive power, I realized from my years of riding Honda motorcycles that Mr Honda was the kind of genius I was looking for. Chamber volume for the muffler was found to be a significant issue when wanting power and quiet in the same solution.

I turned to Burns Stainless steel for tubing and tubing design resolution. Mixing cylinder pulses so that each previous pulse pulled on the pulse that followed seemed to be the approach I should take for the torque that I hoped to find through proper exhaust tuning. That leads to the obvious firing order as the sequence of events that move the exhaust along, thereby reducing the work the engine must do to relieve itself of the gasses that needed a way out of the system.

Soooooo, behold what all that wrought. Can't wait to hear and feel the results. It may be wasted energy on my part, but, noting ventured, nothing gained. If my clearance measurements are correct, it should all fit inside the rear skirt.


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PostPosted: Sun Aug 23, 2015 12:03 pm 
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I am not qualified at all to address this, but how many mufflers do you have there? :)

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