>Is there a difference between a reciprocating engine and an internal combustion engine?

Yes. All reciprocating engines (the type found in most automobiles, whether they are gasoline or diesel) are internal combustion engines. But not all internal combustion engines are reciprocating. The other type of IC engine is called the Wankel engine after its inventor. It was used quite a bit in Mazdas, though I don't know if it still is. The Wankel has a rotating triangular piston that pulls in a gas-air mixture, compresses it, blows it up, then gets rid of the exhaust (the same four cycles that a book I cherished when I was six or so referred to as "suck, squeeze, pop, fooey.")

By the by, external combustion engines are those in which the fuel is burned in the open air -- steam engines mostly.


TEd