Q: How Do the Cylinder Numbers Impact Vehicle Performance and Reliability?

Engines in today’s automotive vehicles come in different sizes and number of cylinders depending on the vehicle size and weight or the work the engine is expected to do. The engine may also be used for performance or for better fuel mileage. Engines will most commonly come in 4, 6, or 8 cylinders. The cylinders each are designed to produce power individually. When you combine them together they will produce more power. For example, if you have three different engines and they are each 25 cubic inches (ci) per cylinder, you would have a 4-cylinder engine with 100 ci, 6-cylinder engine with 150 ci, and 8-cylinder engine with 200 ci. The output horsepower of the engines will increase with the number of cylinders in the engine.

The number of engine cylinders increases the engine load carrying capacity due to the increase in horsepower. Think of a 2000-pound wagon being pulled by four horses, six horses, and eight horses. The four horses can pull the wagon on level ground at ten miles per hour without a problem but can only do this for four hours without stopping to rest. The six horses can pull the same wagon for two hours longer and the eight horses can pull it for eight hours longer. This example shows that as the horses increased, the horses could go farther since they each worked less and therefore did not need rest as often. The engine works the same way; most four cylinder engines will not last as long as the six or eight cylinder engines would before they wear themselves out.

The same holds true for going up a hill. The smaller engine will not be able to pull the 2000-pound wagon up a hill as fast as the six or eight cylinder engine could. When we use a smaller engine in a light load situation, it may perform just as well as the bigger engines but at a lower cost. This is why you will see small engines in small cars and bigger engines in larger cars or trucks. Now we are starting to use smaller engines in heavier applications but with high performance engines that use similar amounts of fuel when extra power is needed and use less fuel when the extra power is not needed. For instance, we may increase horsepower of a 4 or 6 cylinder engine by supercharging or turbocharging it to give it the same power as a 6 or 8 cylinder when charging the engine with added fuel and air. When we get to a low load situation like cruising at a steady speed the engine does not need the extra power and the supercharging or turbocharging is turned off so you have a normal 4 or 6 cylinder and use less fuel.

The reliability of an engine is dependent on a lot of different factors like how the engine is maintained, how much load the engine carries, your driving habits, highway versus city driving, and the terrain you drive. The larger engine with the most cylinders will tend to last longer in situations where the engine works harder or severe driving conditions. The larger engine does not have to strain as much as a smaller engine does when these adverse conditions are encountered.