Q: What Is the Difference Between the Rotary Engine and a Piston Engine?

asked by on November 30, 2015

What is the difference between the rotary engine and a piston engine?

The rotary-style (wankel) engine and piston-style engine are two totally different things, like a boat and a submarine.

The only company that uses rotary-style engines is Mazda; they used it in the Mazda RX-7 and Mazda RX-8 (both are discounted). The rotary engine was a compromise from a family of car engines derived from experiments in the early 1960s by Felix Wankel, a German engineer. Over the years, the displacement has been increased and a turbo was installed to make it faster and to gear it toward car enthusiasts. Wankel engines can be classified by their geometric size in terms of radius (rotor center to tip distance, also the median stator radius), depth (rotor thickness), and offset (crank throw and eccentricity). These conditions function similarly to the internal measurements of a regular piston-style engine’s displacement. Mazda rotary engines have a reputation for being relatively small and powerful, at the expense of poor fuel efficiency. They have been modified over the years to try to accommodate today’s emission standards, but to no avail.

The first commercially successful internal combustion piston engine was created around 1859 and the first modern internal combustion engine was created in 1864. This style engine has been in use in all facets of automotive and aircraft and marine. The piston-style engine has been modified by every car manufacturer in the world trying to make it lighter, cheaper, and more fuel efficient, even though all the basics of the piston-style engine are the same. A crankshaft is connected to either 3, 4, 6, 8, 10, or 12 pistons.

The piston-style engines are bigger and more costly to make and reengineer to suit today’s demands. All in all, the piston-style engines work better than the rotary engine in the vehicles we drive today due to weight and driver demands. However, the rotary engine does have some great advantages over the piston-style engine; it can rev up to or over 14,000 rpm (revolutions per minute) versus the 6,000 rpm maximum of a piston-style engine, which means it can be more useful in racing applications.

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