poormansairforce
Well-Known Member
So we got the muffler built for my son's go kart with a Predator 212 and it works pretty well. I know this isn't an airplane but it will carry over and since this was being discussed on another thread I thought I would start a new thread rather than take away from that thread.
I took some decibel readings while standing 10' behind the straight pipe. I measured about 80db and after the muffler was mounted it measured about 72db. The sharpness was noticeably muted. The header pipe is SS and measures 1" od and has .6 sq in of area inside. The muffler was made from a 1 1/2" id exhaust pipe joiner section that measures 3 3/4" long. I welded a SS nut to a SS washer that had the same diameter as the header pipe and in turn that was fusion welded to the end of the header pipe with the nut on the inside. One end of the outer can was reamed to slip snuggly over the header pipe and the other end was drilled for a 1/4" SS bolt that holds the muffler onto the end of the header via the nut. The header pipe has 4" straight section after the 90 degree bend that was drilled with 16-1/4" holes in a pattern of 4 rows with 4 holes each. Each row was drilled incrementally 3/16" farther back so the exhaust gets broken up into 16 pulses with each one having to take a different length path to the exhaust port on the bottom front end of the outer can. Another can over the outside of the first can with staged holes would really quite it down. We also could have added to the header pipe length and the extra distance would have toned it down more. It weighs mere ounces. The road had too much traffic to get any speed readings but my son didn't think it hurt the power at all.
Note: This is a brand new engine so he is not running it very hard.
[video=youtube_share;s-EBwXcc918]https://youtu.be/s-EBwXcc918[/video]
I took some decibel readings while standing 10' behind the straight pipe. I measured about 80db and after the muffler was mounted it measured about 72db. The sharpness was noticeably muted. The header pipe is SS and measures 1" od and has .6 sq in of area inside. The muffler was made from a 1 1/2" id exhaust pipe joiner section that measures 3 3/4" long. I welded a SS nut to a SS washer that had the same diameter as the header pipe and in turn that was fusion welded to the end of the header pipe with the nut on the inside. One end of the outer can was reamed to slip snuggly over the header pipe and the other end was drilled for a 1/4" SS bolt that holds the muffler onto the end of the header via the nut. The header pipe has 4" straight section after the 90 degree bend that was drilled with 16-1/4" holes in a pattern of 4 rows with 4 holes each. Each row was drilled incrementally 3/16" farther back so the exhaust gets broken up into 16 pulses with each one having to take a different length path to the exhaust port on the bottom front end of the outer can. Another can over the outside of the first can with staged holes would really quite it down. We also could have added to the header pipe length and the extra distance would have toned it down more. It weighs mere ounces. The road had too much traffic to get any speed readings but my son didn't think it hurt the power at all.
Note: This is a brand new engine so he is not running it very hard.
[video=youtube_share;s-EBwXcc918]https://youtu.be/s-EBwXcc918[/video]