New Mufflers for a mid 60s B-Body

[Voetom]

Had a lot of parts left over from other projects and decided to use them to build these two, large, st. st 3" in and out mufflers for my pal's 1966 or 1967 Dodge Coronet.

They have 21.5" bodies that are 11" by 5" and are made from 409 and 304 st st.. They have a very good pattern perforated internal tube surrounded by st. st 304 wrapping material (3/8" thick) and then the entire muffler is packed with ceramic fiber, selected for its very good acoustic properties.

These should be very quiet with minimal hiss, resonation, and they should have a low rumble at idle much like Magnaflow or Goerlich XLERATORS but quieter and less drony.

Shown next to one of these is a replacement turbo Corvair 2.5" in and out muffler. These new ones are very large and relatively heavy with all the HD stufff used in/on them.

 

[R413]

Don't count on that. We can see right through them!
Have ear protection ready for first drive, and surely when the packing is gone.

 

[Voetom]

What is different is that the st. st wrap stops any blow out. It acts like a one way filter. Sound through it and no ceramic out. Without the st. st. sock material, you are dead on, it all blasts out pretty quickly.
Here the stuff is on the VOE mufflers I built. Some are going on 22 years old now.

For numbers, some very similar to these flowed about 90% of an equivalent open 3" diameter, 2' long pipe and had sound levels of 71, 83, and 89 dBA at 10 feet (idle, 2200, and 3500 rpm). The little Corvair one had 53% airflow and sound levels of 69, 83, and 91 except this larger ones are missing much of the hiss and spit of the little ones. Very smooth and tame they are.

 

[nitro_rat]

The large case Xlerators are relatively quiet and don't usually drone too bad but they have a stamped end cap and rolled body like a turbo muffler. Even though the ends are welded on, they're still made more like a traditional muffler. Welded bodies like a Flowmaster tend to resonate more in my experience. One way to find out what they do...

 

[Voetom]

Nitro Rat, thanks for your comments. The XLERATORs we used and tested have welded cases, like the ones I built. This is one of the very early ones, a 14" case. These are relatively loud and that is due to the short case and the perf pattern they used. The big ones, like you mentioned, used a different pattern and they really work!

 

[nitro_rat]

Nitro Rat, thanks for your comments. The XLERATORs we used and tested have welded cases, like the ones I built. This is one of the very early ones, a 14" case. These are relatively loud and that is due to the short case and the perf pattern they used. The big ones, like you mentioned, used a different pattern and they really work!

View attachment 1804477

Yep, I've sold those for decades. I tossed my physical copy of that display model because that itchy fiberglass hair coming out of it everywhere. The current ones don't look exactly like that anyway. But notice that the ends are stamped and there isn't a butted "corner" weld. This significantly reduces resonance compared to a welded "box"