An Offenhauser sprint "midget" racer

Offenhauser was an American racing engine manufacturer that operated from 1933 to 1983.

The Offenhauser engine, familiarly known as the "Offy", was developed by Fred Offenhauser and his employer Harry Arminius Miller,[1] after maintaining and repairing a 1913 Peugeot Grand Prix car of the type which had won the Indianapolis 500. Impressed by the double overhead cam, four valve per cylinder design, which was a great leap forward at the time, they designed an engine on similar principles. Originally, it was sold as a marine engine. In 1930, a four-cylinder 151 cu in (2.47 l) Miller engine installed in a race car set a new international land speed record of 144.895 mph (233.186 km/h). Miller developed this engine into a twin overhead cam, four cylinder, four valve per cylinder 220 cu in (3.6 l) (3.6 L) racing engine. This would be used in midgets and sprints into the 1960s,[2] with a choice of carburetor or Hilborn fuel injection.[3] When Miller went bankrupt in 1933, Offenhauser bought the shop and the rights to the engine. He and another Miller employee, draftsman Leo Goossen, further developed the Miller into the Offenhauser engine.

One of the keys to the Offenhauser engine's success was power. A 251.92 cubic inch (4,128.29 cm³) twin-cam four-cylinder racing Offy with a 15:1 compression ratio and a 4.28125-by-4.375-inch (108.744 × 111.1 mm) bore and stroke, could produce 420 hp (310 kW) at 6,600 rpm (1.77 hp per cubic inch (81 kW/L). Other variants of the engine produced up to 3 hp per cubic inch (137 kW/L). Another reason for the engine's success was reliability; unit construction (no separate cylinder head) meant the engine was not vulnerable to head gasket or cylinder stud problems and allowed for higher cylinder pressures.

From 1934, through the 1970s, the Offenhauser engine dominated American open wheel racing, winning the Indianapolis 500 27 times. By then, the company had already been sold, right after World War II, to Meyer-Drake, who continued to build the engines. From 1950 through 1960, Offenhauser-powered cars won the Indy 500 and achieved all three podium positions, winning the pole position in 10 of the 11 years. In 1959 Lime Rock Park held a famous Formula Libre race, where Rodger Ward shocked the expensive and exotic sports car contingent by beating them on the road course in an Offenhauser powered midget car, which was normally considered competitive for oval tracks only.

When Ford came on to the scene in 1963, the Offy lost its dominion over Indy car racing, although it remained a competitive winner through the mid 1970s even with the advent of turbocharging. Before turbo boost limits, over 1,000 bhp (750 kW) could be attained using around 120 in Hg (44.3 psi (305 kPa)) boost. The final 2.65 litre 4 cyl Offy, restricted to 80 in Hg (24.6 psi (170 kPa)) boost pressure, gave 770 bhp (570 kW) at 9,000 rpm. However, the Cosworth DFX soon proved to be unbeatable and the Offy's last victory came at Trenton in 1978, in the hands of Gordon Johncock's Wildcat. The last time an Offy-powered car raced was at Pocono in 1982 for the Domino's Pizza Pocono 500, in an Eagle chassis driven by Jim McElreath, although two Vollstedt chassis with Offenhauser engines failed to qualify for the 1983 Indianapolis 500.

World Championship Indy 500 summary

Season Cars Entered Winning Driver Second Driver Third Driver Polesitter Race Report
1950 31 Johnnie Parsons Bill Holland Mauri Rose Walt Faulkner Report
1951 32 Lee Wallard Mike Nazaruk Manny Ayulo Report
1952 30 Troy Ruttman Jim Rathmann Sam Hanks Fred Agabashian Report
1953 32 Bill Vukovich Art Cross Sam Hanks Bill Vukovich Report
1954 34 Bill Vukovich Jimmy Bryan Jack McGrath Jack McGrath Report
1955 35 Bob Sweikert Tony Bettenhausen Jimmy Davies Jerry Hoyt Report
1956 32 Pat Flaherty Sam Hanks Don Freeland Pat Flaherty Report
1957 31 Sam Hanks Jim Rathmann Jimmy Bryan Pat O'Connor Report
1958 31 Jimmy Bryan George Amick Johnny Boyd Dick Rathmann Report
1959 33 Rodger Ward Jim Rathmann Johnny Thomson Johnny Thomson Report
1960 33 Jim Rathmann Rodger Ward Paul Goldsmith Eddie Sachs Report

In their 11 World Championship years, Offenhauser partnered for at least one race with the following 35 constructors:


  1. ^ "Fred Offenhauser". National Midget Auto Racing Hall of Fame. 1999. Retrieved 2008-09-06. 
  2. ^ Circle Track, 9/84, pp.82-3.
  3. ^ Circle Track, 9/84, p.83.

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