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Packard Dynamometers – Running in and Testing Machines

The recent article: “Packard 336 Roadster on a Chassis Dynamometer in Detroit” received quite a bit of attention and a large number of comments. Thanks to reader Tin Indian, who has identified the scale unit as a Toledo, and the Dyno as being built by the Sprague Electric Works we now know more about it and other Sprague equipment used at the Packard Factory.

The lead photo shows a Sprague Engine Dynamometer at the Wright Aeronautical Co. with a 717.8 c.i. (11.76 liters) Hispano-Suiza V-8 aircraft engine mounted on it. The water-cooled s.o.h.c. V-8 aircraft engine was designed by the legendary Swiss engineer Marc Birkigt and introduced in Feb. 1915 and is a story in itself.

Packard had been using Sprague Electric Works dynos and running in gear since before WWI. A dynamometer does not read power per se but measures the number of foot-pounds of torque an engine produces, and by using a mathematical formula it is converted to horsepower. View the earlier article showing the Packard on a chassis dyno in an Engineering Test Lab in Detroit. 

1921 Packard Six Engine Being Run-in

  • Sprague running-in machine with a 15 h.p. electric motor runs spins a Packard engine through the transmission in high gear at 625 r.p.m. for an hour. The next four hours it turns at 1000 r.p.m. in second gear.

An article found in “Automotive Industries” June 2, 1921, titled “Routine Factory Tests and Final Inspection of Packard Engines” describes the procedures used for running in and dynamometer testing all Packard car and truck engines and transmissions. A 32-step process was followed by two hours of dyno testing time per engine.

View earlier articles about chassis and engine dynamometers here. The lead image is courtesy of the University of Toledo Archives.

  • One of 15 “silent” dynamometer rooms equipped with 150 h.p. Sprague Electric units testing five engine and transmissions every day for two hours. The machine operator is using a stethoscope to check for engine noises.

Packard Engine Running on a Testing Dyno

3 responses to “Packard Dynamometers – Running in and Testing Machines

  1. That is pretty comprehensive quality control for engines. Was Packard ahead of its time with this or did other makers do extensive testing and running in.

  2. He’s using a stethascope, not a microphone. Dynamometers measure torque. That’s what they do. Horsepower is derived from the torque reading, as you said.

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