Flat-ten engine

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A flat-ten engine, also known as a horizontally opposed-ten, is a ten-cylinder piston engine with five cylinders on each side of a central crankshaft.

There are no known flat-ten engines which reached production.

In the early 1960s, Chevrolet built several prototype flat-ten engines as part of an aborted program for family of Modular Engines to replace the Chevrolet Turbo-Air 6 flat-six engine.{{cite web |url=http://www.curbsideclassic.com/automotive-histories/engine-prototype-the-stillborn-corvair-gen2-modular-engine-from-two-to-twelve-cylinders/ |title=Engine Prototype: The Stillborn Corvair Gen2 Modular Engine – From Two to Twelve Cylinders |last=Niedermeyer |first=Paul |date=14 June 2017 |website=www.curbsideclassic.com }} This development program investigated flat engines with between two and twelve cylinders, with the flat-ten version being known as "P-10" ("pancake" engine). Although the program was initially intended to develop an engine for the 1964 Chevrolet Corvair (which is rear-engined with rear-wheel drive), the flat-ten version was fitted to an experimental 1962 Chevrolet Impala (a front-engined car which was converted to front-wheel drive).{{cite magazine |last=Newell |first=Dave |date=April 1995 |title=Hitting on All 10 |magazine=Corvair Communique |publisher=Corvair Society of America |volume=17 |number=4 |pages=13–16}}