Skip the auto shop - Our mechanics make house calls

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

asked by on

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

A: The rotary-style (wankel) engine and piston...

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: clicking noise in engine

Internal engine noises vary by the size of the parts making the noise and how fast they are moving. Think of drums, cymbals, or guitar strings. Smaller, lighter engine parts make clicking or tapping sounds, while bigger heavier parts make...

Q: Is the Engine "interference" or "non-interference"?

Hey there. In the context of engines, interference timing refers to the use of a timing belt rather than a chain, such that when this belt breaks, the camshaft and other internal parts (like valves) will cause major damage to...

Q: Slow start up on a Mazda RX-8

You say it starts. If it cranks normally then it is not the starter. But if it turns to a normal speed and it starts out driving normal, with a continuous rapid starting sound then that means the starter is...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...