Muffler Theory

Find answers to all of your automotive questions here
Post Reply
Posts: 9
Joined: Thu Nov 18, 2010 7:08 pm
Location: Pennsylvania

Muffler Theory

Post by wmacdonald » Sun May 22, 2011 12:05 pm

The attached photo shows the muffler pieces as-received with my ca. 1912 Little Giant bus. The four shells are 4, 5, 6, and 7 inches in diameter and 20 inches long. The exhaust enters the inner shell through two 1 3/8" diameter pipes (one from each cylinder) and gets from one shell to the next though nine 3/8" diameter holes. Doing the math, that's 2.97 square inches inlet and 0.99 square inches outlet. Having no experience with this type of muffler, that seems like a LOT of restriction. In my case, the engine is a 2 cylinder, 5" bore and 4" stroke which works out to 157 cubic inches.

Does anyone know how this type of muffler is supposed to work, and how the hole size and number is determined?


Wayne MacDonald

jeff deringer
Posts: 99
Joined: Thu Nov 11, 2010 6:56 pm
Location: Camas, Wa


Post by jeff deringer » Tue May 24, 2011 8:48 pm

Well, it looks a lot like the muffler on my 14 Overland 4 cyl 35 hp that works fine. One thing you can do is install an exhaust cutout ahead of the muffler that you can engage on hills. Plus it makes it sound like you are going faster on flat land!

Post Reply