Updated: Nov 5, 2021
By Hosea Embury
You may have heard people talking about whether your car is a 4 cylinder or a 6 cylinder. Your car might have a V6 badge on it. But what all does this mean? 🤔
The number usually is how many pistons the engine has.
Let's see what the piston does in a one cylinder internal combustion engine (ICE). The piston converts the downward force from the ignited fuel mixture into rotating force to ultimately turn your car’s wheels. Here is a diagram of a single cylinder engine.
The job of the piston is the same across all engine configurations. If the single cylinder engine was considered a configuration it would be the simplest. But a configuration means the way multiple pistons are set up in an engine. The most common configurations are the inline engine and the V engine.
The inline engine.
Inline engines range from the inline 2(parallel twin), to the inline 14. By far the most common inline engine, not to mention the overall most common configuration, is the inline 4. It has 4 pistons in a line with each other. Here is a diagram of a inline 4 engine.
About 38% of cars on the road have inline 4 engines. Some example cars with inline 4 engines are a Honda Civic and a Toyota corolla. The inline 6 is another example of a common inline engine used commonly on trucks and older SUVs. Here is a inline 6.
The inline 6 is one of the smoothest running engines.
Another example is the inline 3. It is basically a inline 6 cut in half.
Smart cars have inline 3 engines.
No matter how many pistons the engine has the setup of pistons are the same-in a line.
V Engines are set up with the pistons moving in a V-shaped pattern. V Engines range from v-twin, 2 cylinder, to V24, a 24 cylinder engine. The most common V engine is the V6 engine.
The purpose of the V Engines is to shorten the engine and save space in a engine compartment. The V6 engine is typically used in bigger passenger cars and light trucks. For example the Lexus IS and Nissan Frontier have V6 engines.
Another common V engine is the V8.
The V8 engine has 4 cylinders on each side, or bank. V8 engines are used in trucks and sports cars, like the Nissan Titan and the Chevrolet corvette.
You may have heard of V12 super cars. The V12 is what you think it is, a V engine with 6 pistons on each bank.
V12 engines are used on super cars like the Lamborghini adventador, Ferrari 812, and the Rolls-Royce phantom. V12s are usually very powerful engines.
Another type of engine configuration is the W engine.
The W engine is set up with the pistons moving in a w-shaped pattern. Here is a Bentley W12.
And here is a diagram of the famous W16 from the Bugatti Veyron.
These engines are some of the most powerful engines made.
Other Engine Configurations
The Flat Engine
The flat engine, also referred to as horizontally opposed or "Boxer" engines have the pistons moving similarly to a V Engines but the pistons move 180 degrees from the opposite bank.
These engines are commonly found on Subarus. They come in a variety of two cylinder 4-cylinder and 6-cylinder configurations.
The pistons in a x configured engine move in shape of an x.
They are similar to radial engines.
Radial engines are used on aircraft.
Wankel Rotary engine.
Compared to the reciprocating piston engine, the Wankel engine has more uniform torque; less vibration; and, for a given power, is more compact and weighs less.
The rotor, which creates the turning motion, is similar in shape to a Reuleaux triangle, except the sides have less curvature. Wankel engines deliver three power pulses per revolution of the rotor using the Otto cycle. However, the output shaft uses toothed gearing to turn three times faster giving one power pulse per revolution. This can be seen in the animation below. In one revolution, the rotor experiences power pulses and exhausts gas simultaneously, while the four stages of the Otto cycle occur at separate times. For comparison, in a two-stroke piston engine there is one power pulse for each crankshaft revolution (as with a Wankel engine output shaft) and, in a four-stroke piston engine, one power pulse for every two revolutions.
The four-stage Otto cycle of intake, compression, ignition, and exhaust occurs each revolution of the rotor at each of the three rotor faces moving inside the oval-like epitrochoidal housing, enabling the three power pulses per rotor revolution.
The definition of displacement applies to only one face of the rotor as only one face is working for each output shaft revolution.
The engine is commonly referred to as a rotary engine, although this name is also applied to other completely different designs, including both ones with pistons and pistonless rotary engines.