thumb|250px|Series 452 engine in the Deutsches Technikmuseum Berlin
The Cadillac V16 engine is a term that applies to two different Cadillac-designed V16 automobile engines, an overhead valve 45-degree model produced between 1930 and 1937, and a 135-degree side valve between 1938 and 1940. Both were used in its most luxurious model line, the Cadillac V16.
Cadillac produced two of only four production gasoline-fueled V16 engines in history. The company has twice since attempted to build a new V16 engine, once in the 1980s and again in 2003 (the Cadillac Sixteen), neither making it into production.
Series 452
With its competitor, Packard, already having sold a V12 engine to compete with Cadillac's eight-cylinder cars, work began late in the 1920s to produce a competitive multi cylinder luxury car. Lawrence Fisher, Cadillac General Manager, leaked to the press that the company would also build a V12, hoping to keep the real engine secret.
The first generation Cadillac V16 is functionally two overhead valve Straight-8 engine engines on a common crankshaft and aluminum crankcase. The independent cylinder blocks and heads meet at a 45° bank angle. Engineering features included a counterweighted crankshaft, overhead valves, and hydraulic lash adjusters. It also had two single barrel updraft carburetors, A production version with a base V8 and the option of the V12 engine was planned, but was never approved for production and was ultimately shelved around 2008.