Frank Kurtis founded Kurtis Kraft in the late 1930s when he built his first midget car chassis in southern California. The company grew steadily through the 1940s to become one of the most prolific builders of American racing cars across all major categories — midget cars, sprint cars, quarter midgets, sports cars, and USAC Championship cars. Over its operational life, Kurtis Kraft produced 387 midget car chassis and 120 Indianapolis 500 cars, including five race winners.
The Offenhauser engine that powered Kurtis Kraft's most successful cars originated in a collaboration between Fred Offenhauser and Harry Miller in the late 1920s and early 1930s. A four-cylinder 151 cubic inch Miller engine had set an international land speed record of 144.895 mph in 1930. Miller subsequently developed it into a twin overhead cam, four-cylinder, four-valve-per-cylinder 220 cubic inch racing engine. When both Miller and his successor company went bankrupt in 1933, Fred Offenhauser purchased the rights, tooling, and drawings at the bankruptcy auction and reopened nearby, retaining former Miller employees including draftsman Leo Goossen to continue development.
At Indianapolis, the displacement rules shifted across the decades. Under AAA rules the Offenhauser ran in 270 cubic inch form; under USAC rules the limit became 252 cubic inches, with a 255 cubic inch variant used during earlier fuel-consumption formula years. In all configurations the engine's key characteristics remained consistent: monobloc construction that eliminated the head gasket failure modes afflicting multi-piece engines, dual overhead camshafts, and exceptional power density. A naturally aspirated 251.92 cubic inch Offenhauser with a 15:1 compression ratio could produce 420 horsepower at 6,600 rpm — approximately 1.77 horsepower per cubic inch, far exceeding rival designs of comparable displacement.
Kurtis Kraft's Indianapolis cars adopted what became known as the roadster layout, mounting the engine offset to the left within the chassis so the driveline ran beside rather than beneath the driver. This allowed a lower seating position and a reduced overall height, lowering the car's centre of gravity — critical on the slightly banked Indianapolis oval where smooth cornering over 200 laps mattered as much as outright speed on the straights.
The pairing won five consecutive Indianapolis 500s in the early 1950s, cementing Kurtis Kraft's status as the premier American racing car constructor of the period. The Offenhauser's reliability complemented Kurtis's chassis engineering: the engine's monobloc construction proved resistant to the sustained high-rpm oval running that destroyed less robust units, while Kurtis's fabrication standards produced cars that could last the full 500-mile distance without mechanical failure.
The Offenhauser engine's dominance of American Championship Car racing lasted from 1934 to the mid-1970s, spanning the entire operational peak of Kurtis Kraft and the subsequent roadster era. In the eleven years from 1950 to 1960 during which the Indianapolis 500 counted as a round of the FIA World Drivers' Championship, Offenhauser-powered cars won every edition. In each of those years Offenhauser-engined cars secured all three podium positions.
The Kurtis Kraft midget car chassis featured a smaller-displacement version of the same Offenhauser architecture. Kurtis sold the midget car portion of his business to Johnny Pawl in the late 1950s and the quarter midget business to Ralph Potter in 1962, concentrating resources on the Championship Car programme. Frank Kurtis was subsequently the first non-driver inducted into the National Midget Auto Racing Hall of Fame.
The Kurtis-Kraft Offenhauser's dominance at Indianapolis in the early 1950s established norms that outlasted the company itself. The roadster layout — front engine, offset driveline, low seating position — became the standard American Indy car configuration and was refined by successor builders including A.J. Watson and others throughout the late 1950s. The Offenhauser engine itself continued winning at Indianapolis until 1976, accumulating 27 victories in total across all chassis combinations, the highest total of any engine in the race's history. The Kurtis Kraft and Offenhauser combination at their peak represents the defining technical expression of American oval racing in the post-war decade.