The Miami 12 Engine

By Sigur Whitaker
 
Carl Fisher, Jim Allison and Arthur Newby enjoyed racing their Purdy Boat Company cruisers on the Great Lakes and while wintering in Miami Beach. To get a competitive advantage, they wanted a very powerful engine. The solution was just down the street from the Indianapolis Motor Speedway at Allison Engineering owned by Jim Allison.
 
In 1919, Jim Allison instructed Allison Engineering’s chief engineer Norman Gilman to build a marine engine for use in his yacht. Gilman protested that the engine would be too expensive to be sold commercially. According to Jim Allison’s Machine Shop, the first Thirty Years, Allison replied, “We are not running this shop for profit. Your job is to build the best engine possible.”
 
Allison Engineering, using the expertise it developed with the Liberty aircraft engine, designed a marine engine with between 400 and 450 horsepower. Using cast-iron cylinders and a heavy bronze crankcase, the engine was lighter than the conventional marine engine made of welded steel. It was effectively a waterproof aircraft engine which had been modified for use in a yacht. There were variations in the eight Miami 12 engines it produced. Some had one carburetor, some two. Two spark plugs per cylinder were used except for the racing engines which had three spark plugs per cylinder. The control levers could be positioned on either the right side or the left side. 
 
Allison, Fisher and Newby bought the engines at $25,000 per engine, estimated at $464,770 today. The Miami 12 engines, also known as the Allison 12 engine, had the desired impact. Equipped with two Miami 12 engines, Allison’s cruiser, the Sea Horse, achieved a speed of 26.5 mph. The Sea Horse won the express cruiser race in the 1921 Buffalo regatta held on the Niagara River and placed third in the 1921 Detroit regatta held on the Detroit River. Another Allison yacht, the Aye Aye Sir, also raced in the 1921 Detroit regatta and placed second in the free-for-all. Impressively, this boat ran 260 miles from Detroit to Buffalo without needing engine maintenance.
 
Allison also had a Miami 12 engine installed in the Aye Aye Sir II built for the 1922 Miami Regatta. The boat had a speed of 43 mph. It didn’t participate in the races as the propeller shaft snapped and punched a hole in the hull of the boat which sank in the shallow waters of Biscayne Bay.
 
Several of Fisher’s boats were equipped with Miami 12 engines. In a letter to Jim Allison dated September 15, 1922, Fisher sang the praises of the Miami 12 engine after the Shadow F traveled from Miami to New York City. “The Shadow F arrived the day before yesterday in perfect condition, after a 1,000 mile run; nothing was necessary to do to the engines except to tighten one governor spring, which required about five minutes to do so. The job of building is perfectly beautiful—I haven’t seen any boat job equal to it, and the engine installation is marvelous. Yesterday we took the boat at full speed for about twenty miles without anybody being in the engine room."
 
Arthur Newby’s yacht Altonia II was also equipped with two Miami 12 engines. Newby received his new express cruiser from Purdy Boat Works in late November 1921. With a cruising speed of 35 miles per hour. Altonia II left Trenton, Michigan and made her way via the Erie Canal to the Hudson River. From New York City, the Altonia II went down the coastline of the United States to Miami Beach for the winter season.
 
Jim Allison was unhappy with the excess vibrations and noise from the available auxiliary engines which supplied electrical power for ship functions.  Responding to his mandate to produce a better product, in 1920, Allison Engineering developed a four-cylinder auxiliary engine called the “Miami Lite” and occasionally known as the “Allison Lite.” The Miami Lite was a four-cylinder engine which powered a General Electric generator.  Unlike the Miami 12 marine engines, the Miami Lite was available commercially. A sales brochure touted its lack of vibration and its quietness.
 
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