Part of automotive and aircraft engine manufacturing has always involved scientific testing to find power output. Once a baseline power output figure has been found, further tuning and changes can be tested and compared to it. Above can be seen a circa 1920 H6 Hispano-Suiza chassis on test, with each rear hub connected to a dynamometer. By adding the power figures together from each side, engineers were able to find out exactly how much engine power was lost by passing through the drivetrain. Photo courtesy of Isabelle Bracquemond.
The three photos above show the testing of Liberty aircraft engines. Part of accurate aircraft engine testing is to determine the amount of power lost at higher altitudes due to lower atmospheric pressure. The left and center photos above show a Packard Truck outfitted with a Liberty aircraft engine dynamometer.
By mounting the rig on the back of the truck and driving it to the top of Pikes Peak, accurate testing of power loss due to the height could be calculated. The center photo shows a turbocharger fitted for testing, with Dr. Sanford Moss an early expert on turbo and supercharging on the far right. The right photo photos shows an X-24 Liberty being tested. Follow the links to enginehistory.org for more information.