Formula for size of mufflers..
 

I have had the girls at the wife's office saving their empty mousse cans and have a bag full...each is the 8.0oz size..

Someone told me one time that the muffler or combination of mufflers needs to have ten times the volume of the motor cubic inch or cc

True or not...

What would be a good size of inlet and outlet tubes be...or does someone have a formula for this also..

Any help would be appreciated
BB1

Formula for size of mufflers..
 

BB1; Im sure there are ways to calculate all this, and for sure if you are wanting a tuned setup there is plenty of info out there for calculating tuned pipe design.
Ive been working on mufflers and headers for myself and some friends. I am using .875 ; .049 wall tubing on headers because I started working on a BME 102 and that was close to the size of the exaust port, nothing scientific. I have also been able to shape it into the size needed for some other motors that do not have a round exaust port. The larger single cylinder motors would probably need something a little larger.
As for volume I would say get as much as possible, within reason of course :stupid: Less volume = more noise. Im sure there is probably a point where its not worth the effort or there just isnt room for anything bigger.

As soon as I get some plane building done I plan on doing some more muffler testing.
Want to run some tests for me?? Do you have a DB meter??
I would be glad to fix you up with something, not free but very reasonable if you could give me some feedback as to sound and performance.

Im not sure if a Moose Can will hold up to a gasser, they are awful thin.

Adam

Formula for size of mufflers..
 

I don't have anything over a g62....figured that two of the cans might be big enough...and I'm sure that I can TIG weld them together side by side..
I measured a BCM off of my RCS 180 and one can is a little smaller in volume than theirs...

Thanks anyway, I'm just poking around...
I usually have to run the stock (steel) mufflers that come with the engines because of the 95bd required at our field...

Formula for size of mufflers..
 

If you can get the Moose cans to hold up there are some larger ones out there. Ive got I think a 16 ounce one from somewhere. If you can Tig weld, the alum tubing isnt that expensive and with some baffling you can get well under 90 db with very little loss from an open header. ~ 200 -300 rpm
The cannisters I made for the BME were 3" dia and 12" long one for each 51cc cylinder. They also worked well on my 46cc Poulan
Adam

Formula for size of mufflers..
 

Hmmmmmm,

I'm waiting on a 46cc Poulan now....

Where did you place the baffles inside and what size tubing did you use for the inlet and outlet.?
Was gonna machine a piece of aluminum to peen over on the inside of the can for the stinger end and not have to weld it...

Thanks..

Formula for size of mufflers..
 

Here are the parts for one muffler. My friend with the BME designed them and had some of the machining done and I welded them all up. I think we made 8 all together so we all had some to play with. Its a similar layout to some of the commercially available cannisters.
The small tubing is .875 od .049 wall for the inlet and outlet. The larger pieces are 3" od .049 wall.
Ive made a couple of variations on this design that were a little less complicated and were still under 90db on the 46cc Poulan and didnt loose as many rpm.
Adam

Pipe Volume Form...
 

here you go...

pipe cc = engine dispacement cc's

If you have a twin 100 each pipe must be at least 50cc's. Some guys (like me) are going one size up to get a little more quiet and keep the engine from being so peaky or "pipey". KS makes good pipes that provide a mild boost but queit very well. They also make the headers for them. On the bigger gassers they are really the way to go. If you would like to see these you can go to www.desertaircraft.com . It's also best if you have a twin to go with two pipes. 2 into 1 setups can cause surging in the low to midrange.

Formula for size of mufflers..
 

Ahhhhhh,
That helped a bunch....... :)

Thank you...

Re: Pipe Volume Form...
 

Wow; do you realize how tiny a cannister would be that had 50cc displacement??

When Desert aircraft sells you a 50cc cannister that doesnt mean that it has 50cc of volume.
If you look ay the KS site http://www.krumscheid-metallwaren.de...m-schalld.html
and calculate the total volume using their dimensions they are right at the 10X cannister volume for a given displacement.


Adam