We have modified the internal baffling of this muffler to provide a flow-through equivalent to a 2 ¼" round pipe. The inlet pipe being 2" inside-diameter, this means there is very little restriction in the muffler. Ford originally designed this muffler with a 1 ¾" inside-diameter rear tail pipe. We are finding that because the exhaust gases cool as they flow through the muffler, the smaller tail pipe works just fine, as the exhaust gases have cooled sufficiently to take up much less space. All gases (oxygen, nitrogen and carbon monoxide) expand or contract dramatically with only small changes in temperature.

It is interesting to note that the Model "B" muffler that was produced in 1932 is similar to the Model "A" muffler in design, but Ford only used a 1 ½" inside-diameter tail pipe for an engine that was 10 horsepower stronger. Dyno tests seem to confirm that the smaller tail pipe (1 ¾") works just fine with the high performance muffler. We have found the sound is slightly louder, but still has the Model A sound.

This muffler is designed for use with high performance flat heads putting out over 80 horsepower and overhead valve conversions. The standard Aries muffler will work just fine on all flatheads 80 horsepower and under.

Dyno test with High Performance Muffler

Testing was done by Bill Stipe of Specialty Motor Cams (see photos). Bill says: "On my engine it made 86 HP and 150 foot-lbs torque at 3000 RPM, and 72 HP and 172 torque at 2200 RPM. This is a very strong running engine in the car. See my Performance Chart." For information on Bill’s cams or his high performance flat head engines call: 920-467-2895.

Oversize valves