Need Info on Muffler

[Don Templeton]

Ok, I'm making a muffler for the Mac .12 pipe. I'm using a 1/2" ID thin wall aluminum tube shimed up with aluminum from the approx. 3/8" OD stinger. Maybe 1-1/2" long.

Should I drill a bunch of small holes in the sides of the 1/2" tube and cap the end or also put a small tube or hole in the end or what? Obviously, I don't know much about mufflers.

Thanks,

Don :unsure:

 

[GTR]

Don

The key with any muffler is having sufficient volume to allow the gases to cool and slow down. Large volume will also reduce backpressure. If you can get the exhaust to turn through 90-180deg it will have the most effect in cancelling out the noise.

Mr Irwin drops by and he knows more than I'll ever know about mufflers for pipes. Real world practical experience.

GT

 

[TimD]

Capping the tube at the end can cause a lot of backpressure. Usually just having holes in the side of the tube is sufficient on a 21 so I'd say a 12 wouldn't be much different.

 

[Don Templeton]

OK Tim, are you saying holes in the sides but leave the end full open or how about the same size hole in the end as the origional stinger ID?

Don

 

[TimD]

Don,

Yes - holes in the sides of the inside tube with the end left open. The ID the same as or larger than the pipe stinger. Put a larger tube around the outside of the small tube with the holes in it and allow for an air gap between the 2. The larger the gap - the more volume - the better.

Tim.

 

[Don Templeton]

One more question Tim!

Do you seal the larger tube for the air gap at both ends and with no holes in it?

 

[Terry Keeley]

Run an aluminum tube inside the pipe to about the mid point and locktite it in place, you'll be amazed at how quiet it is...

 

[TomMoorehouse]

hey Terry.... how did you say to modify the ops3280 again?

 

[TimD]

One more question Tim!
Do you seal the larger tube for the air gap at both ends and with no holes in it?

Yes!

 

[Terry Keeley]

hey Terry.... how did you say to modify the ops3280 again?

Use some 5/16" brass tubing (9/32 - .281" I/D) and run it into the pipe to the weld (or start of the converging cone for a pipe with a dead band). To be sure it can't go into the motor you can solder a small band of the next bigger tubing on the end. Clean it up good and use loctite to hold it in. You can also put a 1/16" hole in the end of the tube right where it meets the pipe so it will drain if flooded or it gets full of water. :blink:

 

[Ron Jefferson]

Terry: Be careful on what you are trying to use for a quieting device. Last year I met up with Dan Kramer at the Fort Wayne race early in the season using the same internal stinger you use. Yes, it quiets the motor but in Dan's eyes it wasn't an add-on muffler or quiet pipe. Dan aproached me at the Fort Wayne race and said if I showed up at Celina with that pipe, he wouldn't let me run. Not sure why he picked on my application when there were add-on stinger devices with the origional stinger going all the way through at the same event. He simply read the flyer to me that stated " external add-on muffling device or quiet pipe". Guess what... I didn't bother going to Celina.

Bottom line is... Each club has their own set of rules and interpritation of the written I.M.P.B.A. rule. Quiet pipes is really the only safe way to go.

Ron

 

[Preston_Hall]

Terry: Be careful on what you are trying to use for a quieting device. Last year I met up with Dan Kramer at the Fort Wayne race early in the season using the same internal stinger you use. Yes, it quiets the motor but in Dan's eyes it wasn't an add-on muffler or quiet pipe. 

The IMPBA Rule Book actually has an illustration of this device as being legal. That was one of the best moves for the IMPBA - pictures! :lol:

As for a .12 muffler just use something to get by as legal. Not that I normally condon that but a .12 isn't loud in the first place. That is where a DB limit would be a benefit for the IMPBA.

 

[Terry Keeley]

Terry: Be careful on what you are trying to use for a quieting device. Last year I met up with Dan Kramer at the Fort Wayne race early in the season using the same internal stinger you use. Yes, it quiets the motor but in Dan's eyes it wasn't an add-on muffler or quiet pipe. 

The IMPBA Rule Book actually has an illustration of this device as being legal. That was one of the best moves for the IMPBA - pictures! :lol:

As for a .12 muffler just use something to get by as legal. Not that I normally condon that but a .12 isn't loud in the first place. That is where a DB limit would be a benefit for the IMPBA.

Ya, talked to John last fall in Huntsville, he seemed impressed that a little brass tubing could take a 67 from 107 to 92 dB, decided to put it in the book.

 

[Ron Jefferson]

Preston...

Don't get me wrong. I'm all for the quiet pipe rule and pictures are great! The point I was trying to make is that the CD has the ultimate control over who runs and who doesn't. In Terry's case. I don't know of anywhere else around here where he wouldn't be able to run his set-up. Knowing Terry and his quest for the 100mph patch I'm sure he has cleared his "internal stinger" with IMPBA before setting out to Flint or Huntsville on his mission.

Elmira in district 1 has a new 95db rule that they plan to enforce this year. Dan Kramer has another set of rules and I'm sure there's more. I just figured that choosing the safest route (quiet pipe) should cover you in most any circumstance. Maybe not?

I'm not trying to center out Dan here. He stated his guidelines in his flyer and with me he enforced them. I commend him for that. I discussed with him the fact he was going over and above what IMPBA had stated the rule to be and he said he didn't care. "It is very clear in the flyer Ron". End of conversation. I wouldn't have wanted him to deal with me any other way. Straight, and to the point. Just the way I like it!

Ron