1938 Indianapolis 500

The 26th International 500-Mile Sweepstakes Race was held at the Indianapolis Motor Speedway on Monday, May 30, 1938. For 1938, riding mechanics were made optional; however, no teams utilized them in the race. In addition, after seven years, the engine specifications were changed again. The 1930 "Junk" formula was eliminated. Normally aspirated engines were allowed 4.5 liters (down from 6.0 L), and superchargers would be permitted again, with a maximum displacement of 3.0 liters. Any fuel was allowed, which directly affected the race.