Harry Miller (1875-1943) Racecar Designer, and Inventor of the Indianapolis Racer

Harry Miller and his “91” (displacement in cubic inches).  This supercharged straight-8 with overhead valves and hemispherical combustion chambers, dominated US oval track racing, including 12 wins at the Indy 500 from 1921 to 1938, and also set land speed records in the 1920s and 1930s.


Early Years

Harry Miller was born in Menomonie, Wisconsin in 1875.  From a young age he exhibited a fantastic mechanical aptitude, and an imagination for ideas of machines that has perhaps been unrivaled in American engineering since.  He started to work in a machine shop near his home at the age of 13, and left his home not too long after, never completing high school.

As he drifted about the country between 1892 and 1910, he spent his time working in various machine shops, and tinkering.  Lots of tinkering.  The list of mechanical things he was the first in the US to build is quite long.  The first motorcycle (1896).  The first outboard motor (1898).  He neglected to patent either (a mistake he would soon learn not to make) and gave his idea for the boat motor to a young machinist by the name of Evinrude, who modified Miller’s little 4 cylinder outboard motor  and patented it…and by himself inventing an industry.

In 1900, Miller invented a novel spark plug and patented it.  Selling the manufacturing rights, he made a considerable sum and continued his experimentations. In 1905 he invented a carburettor called the “Master Carburettor”.  It was a significant improvement over existing designs and was purchased by a number of automotive manufacturers of the time, including Simplex, an early American sports car that competed in some of the first Indianapolis races.

This began Miller’s association with motor racing, an association with which he would become nationally known.
By 1913 Miller had come up with an improvement on this carburetor, and he named it the Miller.  This carburetor became standard equipment on virtually every American car (Model T’s used them) in the 10’s and early 20’s and made Miller a fortune, which he soon plowed into realizing his lifelong dream, building racing engines.

Age of the Miller 8

Initially, Miller began by rebuilding French Peugeot racing engines, then got a government contract to  build Bugatti aircraft engines under license during WWI.  They were both influential in his first postwar engine designs, straight-8 designs with a combination of Bugatti and Peugeot influences.  They had, most notably, 4 valves per cylinder and aluminum pistons, the first engine with both of these features to be built in the United States.  A look at the list of Indianapolis 500 winners will show that this Miller 8 won the race in a Duesenberg chassis its first time out, in 1922.  The following year, this Miller 8 was altered by reducing the valves per cylinder to two, and the top of the combustion chamber redesigned to a hemispherical shape.  The “Hemi” was born, the first American automobile engine to use this design, as well as the first American racecar to use the design (it should be noted the world’s first successful use was by the Fiat 130HP racer of 1905).
Throughout the 1920s, Miller continued to refine his racing cars.  In 1925 he built the world’s first front wheel drive racing car, using a de Dion style suspension (a world first).  In combination with his straight-8 engine, the car was unbeatable in oval track racing in the US for most of the next decade. Miller went into volume production of the car and sold it to anyone with the means and desire to go racing (the engine listed for $5000, in combination with  a rear drive chassis for a total of 10000…and his revolutionary front wheel drive chassis for $15000).   Performance and reliability of the Miller ’91’ was legendary, developing 250hp at 8000 rpm, and running on methanol fuel.  It was so impressive in general design that it even influenced Ettore Bugatti, who redesigned his straight-8 single cam pushrod engine of the Type 35 to a dual cam cross-flow design in the Type 50 which was similar to that of the Miller ’91’ 8.
Louis Meyer’s 1933 Indy 500 winning Miller ’91’

Birth of the Offenhauser

During this period Leo Goosen (Miller’s draftsman) and Fred Offenhauser (his chief machinist) were approached by several racing drivers, who thought that a 4-cylinder marine engine design invented by Miller in 1926 might have certain competitive advantages.  These men had been instrumental in converting Miller’s ideas into functioning metal since joining his company in the early 1920s, as Miller was unable to draft engineering drawings and while a talented machinist, Miller was nowhere near as skilled at the task as Offenhauser had become.  Miller was an ideas man foremost.
While Miller was busy running his business in the Eastern part of the US in the late 20s, Offenhauser and Goosen built some of these 4 cylinder engines derived from the initial Miller design for the West Coast oval racing scene.  Due to their robust construction and torquey nature, they had good success.  Harry Miller had sold his racing car business in 1929, and his engineering firm went completely bankrupt in 1933, but Miller had one last act left up his sleeve which I will get to momentarily.
Back to this 4-cylinder engine.  After Miller’s bankruptcy, Goosen and Offenhauser set up a small company in the mid 1930s to produce this engine, and other parts, for the racing fraternity.  This begat the era of the Offenhauser, which from the WWII era until the late 1960s, through continuous development, in naturally aspirated, supercharged, and finally turbocharged forms, dominated Indianapolis style racing, and American open wheel racing in general, winning the 500 no less than 27 times.  By the time it won its final Indy 500 race in 1976, the engine developed 1100 hp from just 2.6 liters displacement…a stunning 423hp per liter.  It is remarkable to think this engine, first developed in 1926, was able to last for over 50 years in competitive racing.
The first Offenhauser to win the Indy 500, in 1935
Mark Donohue’s Eagle/Offenhauser Indycar from 1973.  Note the massive turbocharger in top left of the picture.
Mark Donohue’s McLaren/Offenhauser Indy 500 winner of 1972.

Final Act

In 1938, one final important project came Harry Miller’s way.  Gulf Oil company contracted him to build a racing car.  As chief project designer, Miller was influenced by the German Auto Union V-16 rear engined monsters of the day, and came up with a 3-liter supercharged 4 wheel drive oddity with disc brakes all around.  The block and head were cast integrally. Four cars were constructed, and it was a radical design that was unfortunately not successful in 3 attempts at the Speedway in 1938, 1939, and 1941.

Gulf/Miller racer at Indianapolis garages, 1938

Miller’s final years were spent peddling some of his radical project ideas, including for a small 4 wheel drive front engined sportscar (literally 40 years before such cars would become commonly produced, most notably by Audi)  around in Detroit, but he got no listeners, partly due to the unstable global political climate of the late 1930s and early 1940s.  Miller was then simply too far ahead of his time.  The most notable racing engine designer, perhaps in US history, died of heart failure with relatively little notice in a country then swept up in WWII, in May 1943.


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