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thescreensavers
03-25-2013, 07:49 AM
Hey guys,

We have a 0.060 aluminium sheet here and wondering if it is thick enough for muffler duty, we have read about people having issues with holes developing during competition but they don't mention the thickness they used.

For the people that build their mufflers, how thick or thin are you doing them?
dmacke
03-25-2013, 11:47 AM
We have had aluminum mufflers get hot enough that the sleeve that attaches them to the header melt off. Granted the tune was way off causing very high exhaust temps but just some food for thought.
AxelRipper
03-25-2013, 12:58 PM
It really depends on the vehicle. Our snowmobile had no issue with its .035-.060 aluminum muffler shell (don't remember thickness off the top of my head) and not an ounce of fiberglass in the can, but we've also disintegrated aluminum shells on stock bike mufflers on our formula car. Our current formula muffler is .020 steel, and it would have been easier to make if it was .035 aluminum. It all depends on what EGTs you see with your engine and tune, what they are when they reach your muffler and probably a bit of how the muffler is mounted too. We failed a few cases with a rigid mount and vibrating single.
Mbirt
03-26-2013, 05:59 AM
.060" is plenty thick enough, but a few considerations should still be made. Production mufflers with aluminum shells always have fiberglass insulating the housing from flow. Absorptive attenuation is the primary reason for the fiberglass, but an added benefit is the reduced shell temperature. Check out this design guide for Owens Corning Silentex: http://www.ocvreinforcements.c..._Guide_29_Mar_06.pdf (http://www.ocvreinforcements.com/pdf/library/Silentex_Design_Guide_29_Mar_06.pdf)

Secondly, as dmacke mentioned, it's possible for the calibration to be off to the point that you're melting fiberglass due to high EGT's. In my experience, that's when the aluminum muffler shell melts also.

Third, be sure sure to use quality steel rivets if you're going that route. Endurance DNF's due to aluminum rivets on muffler end caps are not that uncommon.