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DLE exhaust

to loud

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SR 7128/03/2020 04:36:23
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433 forum posts
140 photos

Is there any way to make this exhaust for a DLE55cc quieter, like get it down to my new clubs 82db rules, like cut the can open and do something inside it

Before i bin it

cymaz28/03/2020 06:30:02
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9196 forum posts
1186 photos

First and cheapest option is try the pepper pot ends that slip into the exhaust ends.

If that is no good then modify yours, there is a thread HERE.

I have a dle55 which was 2db over in my usual club. It has a canister on it as well. I was advised to change this and that. Not willing to change anything as the motor runs so well it now only flies at another club with a much greater noise limit.

You could give JE and Weston a ring , they both make modified exhausts....may be not cheap and no guarantee that it would get you under. I’ve also read about people putting a stainless steel scouring pad into the exhaust chamber in an effort to cut down on the sound pressure wave ringing the housing like a bell

Edited By cymaz on 28/03/2020 06:38:11

Edited By cymaz on 28/03/2020 06:40:11

Steve J28/03/2020 08:01:08
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1841 forum posts
53 photos

You can play games with the Pitts style exhausts to get them down by a few dB, but you really should be fitting a decent canister. Personally I would be looking at Zimmerman or JMB.

Denis Watkins28/03/2020 08:09:24
4334 forum posts
104 photos

You know that you need internal Volume SR 71, and the above silencer will not cut it

The gas needs somewhere to expand, so a canister is needed as above advice.

they can cost as much as your motor

Jason Channing28/03/2020 08:13:00
149 forum posts

As per the second post pepper posts will bring the noise down , not the best way but they do work.

Ron Gray28/03/2020 09:01:21
1927 forum posts
803 photos

Personally I’ve found that pepper pots make very little difference in noise levels, as Denis has posted, volume is your friend. I run all of my DLEs on cans, the DLE ones are ok but Zims and JMBs are more expensive, for a very good reason. As an example, the DLE can for the 35 is 50mm diam, the equivalent Zim is 60mm.

SR 7128/03/2020 09:57:04
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433 forum posts
140 photos

Well that thread started off fine but very soon deteriorated into a fight, interesting method though Cymaz

john stones 128/03/2020 10:35:23
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11454 forum posts
1516 photos

Pepper pots brought the noise down on a clubmates model, he did lose some grunt though.

flight128/03/2020 10:47:31
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722 forum posts
36 photos

I don't see any fight just different ideas and approacheswink

anyway back to the op question

1. you could try a the peper pots they do make a difference also the prop can make a difference if you can fit a bigger prop at slower rpm to do the same job.( some makes are quiter)

2. check the airframe/cowl is not vibrating to much and generating some noise , cheep well nuts or similar can help.

3. whats very much overlooked is the noise from the carb intake on a 2t can emmit a lot of noise, try a veturi and filter material over the intake not as a air filter as such but to muffle the noise

4. all the little improvements can ad up.

5. make the pits mufferler out of copper instead of stainless (it will make a lot softer noise) in doing so increace the diameter of the pipe that comes off the manifold part by as much as that will fit and install baffle material some thing like this will for an idea saves fabricating to much

the diy solutions are much cheeper than buying

just my penny's worth anny question? wink

Edited By flight1 on 28/03/2020 10:48:36

Edited By flight1 on 28/03/2020 11:03:17

Ron Gray28/03/2020 10:48:02
1927 forum posts
803 photos
Posted by SR 71 on 28/03/2020 09:57:04:

Well that thread started off fine but very soon deteriorated into a fight, interesting method though Cymaz

??????? Maybe I'm blind but can't see a 'fight' in this thread, only individuals personal experiences!

Steve J28/03/2020 10:53:31
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1841 forum posts
53 photos
Posted by SR 71 on 28/03/2020 09:57:04:

Well that thread started off fine but very soon deteriorated into a fight

What fight? Those of us who have been through getting the noise of two stroke petrols down to acceptable levels are saying that you need to be looking a fitting a can. You may also need to look at prop tip speed and airframe resonance.

cymaz28/03/2020 11:01:43
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9196 forum posts
1186 photos

...just people voicing different methods and experiences.

I have a DLE 20ra- got passed after pepper pots installed. My DLE 55 has a canister- still won’t pass...there you go. Everyone has helpful advice in one form or another.

john stones 128/03/2020 11:03:04
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11454 forum posts
1516 photos

Cans are much better, there no doubt there, seen one or two good own designed exhausts that give good results though, depends on your model whether you can go the can route.

SR 7128/03/2020 13:22:40
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433 forum posts
140 photos

Did you read the thread all the way through, they were going at it with each other and were told several times to stop it, would not be allowed on here thats for sure,

Thanks for the ideas, sounds like its a bin job,

cymaz28/03/2020 14:23:54
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9196 forum posts
1186 photos

Yes , it hotted up very quickly....secret

cymaz28/03/2020 14:26:57
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9196 forum posts
1186 photos

This chap downunder usually gives some good advice....here he is on exhausts

Denis Watkins28/03/2020 14:39:41
4334 forum posts
104 photos
Posted by SR 71 on 28/03/2020 13:22:40:

Did you read the thread all the way through, they were going at it with each other and were told several times to stop it, would not be allowed on here thats for sure,

Thanks for the ideas, sounds like its a bin job,

With all our skills, nothing goes in the bin. If you would like to add volume to the Pitts silencer, then you will need to

Aluminium weld, yourself or use a car ally wheel repair man.

You could do it

cymaz28/03/2020 14:56:47
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9196 forum posts
1186 photos

The shock wave coming from the combustion hits the exhaust body and it rings like a bell as it travels around the empty metal tube. The more it has to bend the more the energy is disappearing so quieter the end result. If you can find a second hand one, do some modifications. Baffling, adding internal pipes, that sort of thing.

As Denis said, know a welder who can do Ali...it could be cheaper than buying a muffler that doesn’t work

SR 7128/03/2020 15:10:17
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433 forum posts
140 photos

No im not buying a new one, i had a DLE55 in my 1/3 Bucker, and it was spot on, this was last year when i lived in Cyprus, i sold or gave away everything when i came back to the uk including the DLE, this silencer is a new one i had just bought, looks like ill give up on it as i have to buy a new engine anyway, but i did like the DLE, and i flat packed the Bucker and brought the bits back, need an engine for it,when i rebuild it

Ron Gray28/03/2020 15:25:05
1927 forum posts
803 photos
Posted by SR 71 on 28/03/2020 13:22:40:

Did you read the thread all the way through, they were going at it with each other and were told several times to stop it, would not be allowed on here thats for sure,

Thanks for the ideas, sounds like its a bin job,

Ah, now I understand, you meant on the 'other' forum, not on here!!!!

Looking at your last post, if you're going to buy a new engine then 4 stroke it is!

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