Model A Ford Tapered Muffler


Muffler Type	Miles Per Hour	Engine RPM	Backpressure
$50 Facsimile	40 45 50 55	1500 1700 1900 2000	10 oz 32 oz 46 oz 54 oz
Early Jobber (no longer available)	40 45 50 55	1500 1700 1900 2000	2 oz 4 oz 10 oz 16 oz
Non-Tapered 4" Diameter	40 45 50 55	1500 1700 1900 2000	0 oz 6 oz 10 oz 16 oz
Aries Reproduction Tapered Muffler	40 45 50 55	1500 1700 1900 2000	0 oz 6 oz 12 oz 12 oz

The road tests were performed by Doug Windrem of Ontario, Canada. All tests were performed on a level road at an altitude of 1,000 feet. The temperature was 75¼ F. on a clear sunny day. The tests were actually performed using a 1928 Model A Phaeton. An extra length of special piping was installed between the exhaust manifold and the muffler to be tested (see photo). It was here that the back pressure gauge was attached. The mounting point of the tail pipe was also lowered so a correct fit could be maintained without leakage. Two people rode in the car, one driving and one taking readings on both the "Snap On" brand tachometer and the pressure gauge. The pressure gauge is manufactured by O. T. C. Division, SPX Corporation, Owatonna, MN 55060, tool part #7215 and is specifically designed for testing back pressure on automobiles. The speedometer was also calibrated and tested over the test speeds and found to be accurate within one mile per hour.

Backpressure Gauge Test Setup