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Harry Miller’s first masterpiece, a SOHC 16-Valve – Four Cylinder Engine

Harry Miller was a legendary figure in early racing circles from the teens on up through to the early 1930s. He started his career as a riding mechanic on a Oldsmobile in the 1906 Vanderbilt Cup Elimination race, after suffering a crash in practice he and driver Ernie Keeler went out on the second lap of the race with a broken axle.

By 1908 Miller ended up in Los Angeles, opened his own machine shop and developed the Miller carburetor which became quite successful. He was involved in various other endeavors at the time including rebuilding Bob Burman’s Peugeot racing engine after he had broke a connecting rod in it. During 1916 he built a prototype version of this SOHC 16-valve four cylinder racing – aircraft engine, that did incorporate some Peugeot features, including a long stroke and a gear drive for the camshaft up the front of the engine and many of his own  ideas.

Miller designed his engine with a one piece aluminum crankcase and block that also incorporated the water jackets. The cylinders in this engine were wet-liners of cast vanadium iron inserted into the block with packings. Topping this off was a sohc aluminum four-valve aluminum head. The remarkable design, with a 3 5/8″ bore x 7″ stoke and a 289 c.i. displacement, weighed in at only 410 lb. dry. The aircraft version of this engine was stated to produce a maximum of 155 h.p. at 2900 rpm.

One of the first engines found its way into Barney Oldfield’s Delage racing car. It ended up in several board track races at the time at the back of the pack, due to it needing some development. Oldfield’s famous Golden Submarine, next received one of the engines (possibly the same one) and he entered it at a 250 mile event on the Chicago board track, but fell out early with a broken valve spring. Harry Miller is seen with the Golden Submarine (below)

Oldfield did go on to win a match race with it in Milwaukee that summer, against Ralph DePalma in his V-12 Packard. Just (below) you can see Oldfield and the Sub, lose a race to Ralph De Palma on the 2.5 mile board track at Sheepshead Bay, N.Y. in 1917, in a fifty mile race. The third car seen in the film is a Frontenac driven by its creator Louis Chevrolet.

In St. Louis on the one mile track, Oldfield did manage to set many AAA records with the car in events of up to fifty miles and the car did well on other dirt tracks, but he never had much luck on the long board tracks with it. Oldfield crashed it at Springfield, Ill. in the fall of 1917 and after the resulting fire caused by a punctured gas tank, the damaged body was cut off, with the exception of the cowl.

In 1918 Oldfield again ran the car in several board track events, most of the time finishing behind the top guns of the day. One other car that used the same Miller engine was the Cadwell-Toft car that also produced mix results for both drivers, both before and after WWI. If the war not intervened and Miller had more time to develop the engine, the results may have possibly been different.


The Harry Miller built engine and its components seen (above) in photos and in a cutaway drawing from the Motor Age Magazine, April 26, 1917, issue show his typical extraordinary craftsmanship and well thought out design. Study the drawings to see the unique construction features and note the two piece crankshaft that ran on double row ball bearings. Regardless of its success on the race track at the time, the design laid the ground work for the very successful 183, 122, and 91 c.i. Miller straight eights and the Offenhauser engine to follow.

None of the cars or the racing engines have survived, but R.J.”Buck” Boudeman, has created this marvelous running and driving example seen here. It is an exacting replica built around the one surviving engine with desmodromic valve gear, that Miller was known to produce. Below the pictures is a partial video where Boudeman explains many of the Miller engines features. The photos are courtesy of the Miller/Offenhauser Historical Society, where you can see many more Miller photos and find much more information.


4 responses to “Harry Miller’s first masterpiece, a SOHC 16-Valve – Four Cylinder Engine

  1. David,

    Don’t forget to add inventing the outboard motor and building the first motorcycle in the USA (nice to have on your resume).

    This engine raises the question of why did Miller chose this SOHC layout , when he had already built the Burman-Peugeot DOHC ( twin cam )? I think I know why he went back. What was the inspiration for this design ? It appears that Harry had figured out the benefits of different sized valves, when the Pug and Merc were using the same sized valves.


      • Yes, many knock offs of this engine developed. Borgeson says in his book that the SOHC Miller started as a spec built aircraft engine in the period when everyone was copying the 1914 Merc SOHC for airplane engines. The Merc was basically an aircraft design, it was pirated by WO Bentley for RR and others. However, the Merc had the same sized valves , but the Miller and Chevrolet have bigger intakes, closer to ideal.

  2. David,

    Looking a bit further, the inspiration for this motor may have been Chevrolet’s aluminum Frontenac motor. Perhaps Harry copied the staggered valve sizes, but added the dry liners to avoid catching the “Chevy Vega disease” which surfaced again many years later.


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