Better mufflers for the EJ22/EJ25

[MichaelBurton]

We have been using the SupperTraps on our Sparrow Hawk and have found them to be LOUD. I know I was shouting just then but I had to to be heard above the engine noise. Today we tried mufflers from a KZ1100. The gyro was about 15db quieter but the engine lost some HP. Next week I want to try a preformance exaust for a larger motor cycle.

If you have a great idea I would love to be able to hear it ;) .

[Vance]

Michael, borrow a copy of " the sientific tuning of inlet and exhaust systems" by Smith. It will give you the basics for designing an exhaust system. Volume is the key. A big can with all the pipes going into it and a slightly smaller exit pipe that intrudes into the muffler. It is called a back presure muffler and it requires volume to not reduce power. Round is always better than flat sided for longevity. Playing with chambers alows for an even quieter muffler, but adds weight and expense. A properly designed muffler can be very quiet without reducing performance, Your cam doesn't have enough overlap to make the engine exhaust system sensitive.

It might help to look at what they do on a Porche. They too have a space and weight problem. If you can find something heavy you can always make it out of light material. Good luck, Vance

[Aussie_Paul]

.... for Subaru ej series.

Larry Neal has one on the Golden butterfly, but I do not know how it went. :)

Aussie Paul. :)

[GyroRon]

A quiet muffler that does not cut power is also a BIG muffler. Crawl under any late model full size truck and look at how big the mufflers are these days, it is cause the designers are squeezing more and more power from the trucks engine and yet the exhaust still has to be quiet.

I am not a fan of the supertraps. They ARE loud!!!

The best Muffler I have heard on a EJ Subaru was a Home made muffler on Jake Jacobs custom built two place. It used a old airconditioning system Feon Recharging tank - sorta like a Propane BBQ Grill tank but slightly smaller and lot lighter - that he cut three holes into, one on each side for exhaust going in and one more on the side down towards the bottom for the exhuast going out. Connected it to the engine with flexable stainless steel pipe.

Jakes exhaust was so quiet at idle and under 2000 rpms that you can not hear the exhaust AT ALL!!! All you hear is the prop spinning and the engines valves opening and closing. At higher flight power settings, there was noise but it was bearable, almost like a car going by with the drivers foot to the floor, kinda loud but not very loud.

I have jakes phone number is anyone wants to contact him.

[KenSandyEggo]

Be careful with any after-market mufflers you try. I originally tried a pair sold at off-road shops for VW-based off-road vehicles. One day I was flying up north to a fly-in and all of a sudden the engine noise got extremely loud. After I pulled my shorts out, I played with the throttle and checked all the gauges and everything else seemed normal. When I landed at French Valley, I saw that the inner core had let loose and dropped out and away. When it happened, I was following I-15 on a busy Saturday morning. I checked the newspapers for the next few days and didn't see anything, so I guess it didn't hit anyone. The mufflers couldn't take the heat. The Trapps can.

When I switched to the Trapps, I got favorable comments from the airport-rats that it sounded better. The comments I now get are that it sounds like any other Cessna or Piper taking off. That's good enough for me. My pair has been on for at least 300 hours without a problem. Are you sure some of the noise is not prop noise? Different props can sound a lot different from each other. If you want to hear real noise, remove the Trapps and fly the pattern with just the header pipes. WOW! :eek: I tried that once.

[MichaelBurton]

I thik you got lucky with your reliability on the traps. I am on my third set since september. Also the packing must be removed or it melts and clogs the baffles. The traps are so loud that the aiport manager swore at me and thretend to ban me from the airport if i did not do something about it. He said he was "not trying to be an ass hole" so my guess was that it just comes naturaly.

[KenSandyEggo]

That baffles me, Michael. What happened that you had to replace them? Are they the 18-inchers? Something doesn't sound right. I know about the packing. I believe that I was the one to discover this and first post it several years ago. How many disks do you have in? I don't think that this would affect the noise much, but who knows? I have the maximum in, 12 I believe. The more disks, the better the performance. What engine are you running? I have a 2.2. How are the Trapps secured? They should just hang from the manifolds with a brace bar between them and nothing else. Fastening them to the engine or frame will lessen their longevity, but it shouldn't make them louder, unless your manifolds are cracked or loose. AAI should be using the same Trapps I recommended and Jim saw when mine was there, and I know that the company that made my headers is the one AAI uses, again per my referral. I paid to have the original design work done. Don't know why yours should not last and be so much louder than mine. Our whole exhaust systems should be identical. Maybe you could take a few photos and post them. Maybe I'll notice something different than mine. :confused:

[MichaelBurton]

I have used the long traps and the short traps. I used all the disks that were provided And the mufflers were secured as you have said. They were not rubbing on anything. I am running the 2.2 with the stratus cam grind. I know that AAI had more than one muffler failure. And they lost bolth of the longer traps in the first few hours on the 2.5.

We have not had a problem with the shorter traps other than the fact that they are even louder than the long ones.

[Vance]

Michael, You could try reducing the number of disks untill the performance falls off. It will defiinatly make less noise as you reduce the number of disks. The performance may not fall off til you are down to 4 disks, Different engines respond in different ways. If you could hook the two together with a 1 inch tube it would probably allow you to reduce the number of disks. It always comes down to just try it. You will find that in Smiths book. I had one 95 cubic Harley engine with a lot of cam and I couldn't get it quiet without hurting the performance in the low rpm range, just the oposit of what I expected. Don't be afraid to experment, just try to keep muffler parts out of the prop. Thank You, Vance

[KenSandyEggo]

Michael, when you say they "lost" the mufflers, what do you mean? Did they crack and where, fall off or what? Are the manifolds holding up O.K.? This is really baffling, as mine have held up perfectly.

[MichaelBurton]

The mufflers broke at the top weld. The first one severd and would have fallen but was atached by the crossbar to the other muffler. The others just cracked at the top weld and were found durring a visual inspection. The manifolds were not damaged.

[KenSandyEggo]

I wonder if Trapp changed their manufacturing/welding process. I have the same manifolds and the mufflers have never cracked. Maybe it's because I'm such a nice, friendly, kindly compassionate person....most of the time. :D

[MichaelBurton]

I looked at the inside of the large mufflers when I replaced them with the smaller mufflers. One muffler was original the other had been replaced more thane once. The original had better looking welds on the external tobe and more and better welds on the inner tube. I wonder if they found a "cheeper" manufacture? It could be that they just don't spend the same effort that they did on the mufflers that don't break. Also as I am at a high altitude airport I may be running at a higher rpm for a longer time. The heat and cool cycle may also be diffrent.

[automan1223]

You do not need mufflers.

Now before you go all hinky on me, the reason the supertrapps are loud is because....

THEY HAVE NO TAILPIPE.

Ask any of the guys at the briar patch that heard how quiet my engine got after putting on a 18" tailpipe. They all swore I put a muffler on it.

Also remember where you point the sound, and where the prop is in relation to the sound waves. If you bounce sound off the front of the prop forward you will get a headache.

A long enough exhaust pipe develops enough back pressure to save the exhaust valves. Route the exhaust away from the prop.

Short exhaust systems are a no no. They look cool but are a no no.

Jonathan Weis
NIASE Master Tech.

[KenSandyEggo]

One more question, Michael. How is the brace-bar between the mufflers attached to them? Did you use rod-end bearings or rubber grommets? If you did, that could be the cause of the cracking. The mufflers have to be attached to each other solidly, with no slop from rod-end bearings or bushings.

[KenSandyEggo]

Jonathan, have any pics you can post of your setup?

[MichaelBurton]

One more question, Michael. How is the brace-bar between the mufflers attached to them? Did you use rod-end bearings or rubber grommets? If you did, that could be the cause of the cracking. The mufflers have to be attached to each other solidly, with no slop from rod-end bearings or bushings.

Just the clamps and straight hard connection. The new short exaust has a rubber grommet as part of the muffler design. I put it on. Is that a bad thing?

AAI said the fix was to put some sort of flexable mount from the muffler to the header.

I will try removing some of the disks. Someone said 5 was a good number. I have been tracking the dbs so I will be able to tell you how well it works.

[MichaelBurton]

You do not need mufflers.

Now before you go all hinky on me, the reason the supertrapps are loud is because....

THEY HAVE NO TAILPIPE.

Ask any of the guys at the briar patch that heard how quiet my engine got after putting on a 18" tailpipe. They all swore I put a muffler on it.

Also remember where you point the sound, and where the prop is in relation to the sound waves. If you bounce sound off the front of the prop forward you will get a headache.

A long enough exhaust pipe develops enough back pressure to save the exhaust valves. Route the exhaust away from the prop.

Short exhaust systems are a no no. They look cool but are a no no.

Jonathan Weis
NIASE Master Tech.

Why are short systems a "no no"? Did you connect all the cyl to one pipe?

My old chevy has a long pipe but it needs a muffler.

How long a pipe does it need?

Send me a picture


thanks

[KenSandyEggo]

I'm going by the guy that designed my headers and made them. He said to use absolutely nothing except a solid connection between the mufflers. He said that we want everything to move in unison with the engine. His business is custom exhaust systems for aircraft. I followed his advice and all's been fine for years.

[Michael Stump]

Hmmmm....are you guys using the Stainless Steel "Trapps? I do belive I was one of the first to suggest this idea and had no problems with mine, and that was on the EJ22 with a fairly short pipe. In my case, I only used 6 disks, had very low noise, had no problms with the packing, and all was well. The stainless steel may have something to do with that...and, the mufflers are available in mild steel, but for exhaust, SS may be better. My advice, NEVER POINT THEM DOWN!! Packing likes to fall down and, of course, plug the disks. I have seen this time and time again. Also, the screws holding the guts in place ought to be safety-wired.

I am also convinced that a lot of people cross-up prop noise with exhaust noise (was it Ken J. who suggested that here?). Mine were very quiet (before I sold the gyro), and I know Ken's were quiet (cuz I flew it with him). If not, there has to be something not-so-right....

[teiland]

I had a nice, helpful conversation with Michael Stump yesterday about the Super Trapps. My experience is the same as Michael Burton in that I have found these to be very loud.

As many here know, I broke a weld on one muffler at Mentone this year. At that time mine were attached to each other with a hard mount. Jim just sent me flexible joints for mine which I have installed, still attaching the two mufflers together, although with a softer attachment. With the ability to flex the joint, I made the mistake of aiming the pipes aft towards the prop tips, with horrible results. I now have them aimed straight down, as I did originally.

Per Michael's suggestion, I am going to try removing some discs. I cannot orient mine other than downward without quite a bit of work, but will look into that.

Michael Burton, I am glad to hear that you are using a meter to track the changes, and am very anxious to hear anything that you learn.

[Jerry Carter]

I noticed that Ron Menzie did not use the Super Trapps on his RAF conversion. I believe he said he used a muffler from RAF. He likes this setup and has had no problem with it.

[teiland]

Hi Jerry...............No, mufflers are not a part of the Mod Kit.

I forgot to mention this earlier, but referring back to what Jonathan said, I believe the old RAF muffler with the long pipes and the muffler located along the keel was the least noisy.

And as said, no doubt the prop noise is a huge contributor. I had a Prince P-Tip on my old mod machine for a while and it was much quieter (or at least had a much less offensive tone), particularly to those on the ground below. It did have somewhat of an unpleasant resonance inside the cabin, but still it was quite acceptable. I am working on this area now, too.

[GyroRon]

I am sorry you guys aren't interested in talking to Jake.... I have not heard a gyro that made less noise yet. I am sure his whole exhaust system couldn't cost more than a extra pack of disks for your super traps.

[teiland]

Ron, I am glad you reminded us of Jake. He is quite innovative, isn't he?
I had thought when you mentioned him earlier that I would see him at New Year's, and still hope to be able to do so. If not, I will try to call him.

[gyromike]

I spoke to Jake the Snake briefly at Bensen Days about his muffler system, and he mentioned something about having a screen inside of the cannister to break up/reflect the sound waves.

At least that's what I remember...I think. :rolleyes:

[GyroRon]

Maybe he does Mike, I can't remember. I do remember it was a cheap exhaust but looked sturdy and not too heavy and it was whisper quiet compared to the typical gyro exhaust system. I am sure we will see him at New years