A Complete Guide to 15 Different Engine Types
Just like the internet is the defining invention of the 21st century, the automobile must be considered the most influential innovation of the previous century. With the advent of regular automobile use, the very shape of our nation shifted. Populations that were formerly isolated became intrinsically linked, and people were able to explore more and move of their own volition regularly, and it became an option to work in a different place than you lived. However, despite all the many changes the automobile brought to us, just like the internet, startlingly few people actually know how the car works. When faced with an engine, many of us see nothing but an incomprehensible metal monster. But, whether you are an aspiring “car person” or the most casual of daily drivers, it’s good to have a basic understanding of how the tool so vital to your lifestyle actually works. So here’s an examination of the many engine types that might be powering your car.
Internal Combustion Engine
This isn’t actually one of the types, it’s all of them. Before we discuss the different engine types you might have, it’s important to establish a baseline for what all car engines are. The internal combustion engine works on a relatively simple principle: fuel is injected into the engine, whereupon it is ignited. The heat created by the burning fuel increases the pressure outwards. This increase in pressure drives the movement in the engine, whether that be a piston or a rotor or whatever else. All internal combustion engines share these qualities. Where they differ is in the specifics, the type of ignition, how the rotors or pistons move, how the engine is designed, etc. Therefore, the following engine types are categorical, not exclusive.
The fundamental design of the engine is based on whether the engine uses a piston or a rotor to generate energy. Therefore, there are two fundamental types of engines.
The reciprocating engine is based around the piston. A piston is basically just a flat disc inside of a cylinder that moves in and out as a response to fuel being ignited causing expanding pressure. This in and out movement is the “reciprocation” that the engine type is named for; the energy generated turns a crankshaft, which is what allows the car to move. This is the more commonly used type of engine in most cars.
The rotor engine is a bit of a contradiction. On paper, it works better than a reciprocating engine in nearly every way. It generates energy by a simple rotary, thus the name, which is more compact than a reciprocating engine, works more efficiently, and produces more energy per revolution. However, due to its complex design, the rotor engine tends to be prone to having issues. This means it’s less practical for most consumers, who just want to get from point A to point B without having an issue, but is the engine of choice for race car drivers and anyone who wants to get a high performance car and isn’t concerned about the potential issues.
Number of Strokes
When it comes to reciprocating engines, one defining factor is the number of strokes a piston completes in one cycle. At the moment, this is just between two-stroke engines and four-stroke engines, although six-stroke engines are currently in development.
A two-stroke engine completes its entire cycle in two strokes of the piston, one up and one down. This means that the intake and the exhaust happen simultaneously. This leads to some efficiency issues as compared to four-stroke engines, but two-stroke engines deliver more torque.
Four Stroke Engines
Far more commonly used in consumer automobiles is the four-stroke engine, which is a bit more complex than the two-stroke. The full power cycle is, as the name implies, four strokes, two up and two down. One rotation, or set of two strokes, allows for the intake, and the other allows for the exhaust.
Type of Ignition
Another key factor determining engine type is how the fuel is ignited inside the engine. Many modern innovations are going into fuel ignition systems, as the manner of fuel consumption is a pressing concern as we face the mounting threat of climate change.
Compression Ignition Engine
One of the most basic forms of ignition is compression ignition. One fundamental rule of physics is that, as pressure increases, heat goes up. Compression ignition works by increasing pressure in the fuel without allowing any heat to escape. That increased heat leads to the fuel igniting. The most typical example of a compression engine is a diesel engine. Because no excess energy goes into the ignition and no energy is allowed to escape the system, compression engines are extremely efficient.
Spark Ignition Engine
Most commonly used in consumer cars is a spark ignition engine, which is pretty much what it sounds like. The fuel injected into the engine is ignited by a spark plug. Because of its simplicity, spark ignition engines can work with various different types of fuel.
Electric engines somewhat bypass the type of ignition by not having any fuel to ignite. Instead, batteries store energy chemically, and convert that to mechanical energy to propel the car forward. Such a system has obvious limitations, specifically in the amount and duration of energy that a battery can provide. One more common solution are hybrid cars, cars that can run on electric but have a traditional spark ignition engine as a backup.
Amount of Cylinders
When talking about cylinders, we are specifically discussing reciprocating engines, as rotor engines do not have any pistons, and thus don’t need any cylinders that would contain pistons.
A single cylinder engine just works with one piston pumping up and down. These are efficient engines, with a strong ratio of power to weight. Of course, that ratio doesn’t mean much if the weight is small, which single cylinder engines by definition are. Therefore, you should expect to see single cylinder engines in smaller vehicles, things like scooters, go-karts, and golf carts, but never actual cars.
Multiple Cylinder Engines
There are a few different types of multiple cylinder engines, or rather, different amounts, but they all fall under the same basic pattern. Often arranged in pairs, there are two cylinder engines, four-cylinder engines, six-cylinder engines, etc. Having more cylinders allows more power to be generated, a necessity when it comes to powering consumer vehicles.
Arrangement of Cylinders
Just as the amount of cylinders is a basic aspect of an engines design, as are the way that those cylinders are arranged inside the engine.
The in-line engine is just that, an engine where all the cylinders are kept in a straight line. This is to ensure that all the pistons are lined up properly with the crankshaft. Because of the rigid nature of in-line engines, the larger end of in-line engines are less efficient, since they are all spread out. An in-line engine with four cylinders is considered the industry standard for the most efficient in-line engine.
The V engine is an innovation that allows more cylinders to be lined up together without actually having them all in a line. However, many cylinders there are, they are arranged in V-shaped pairs, across from each other but aiming at the same point. This allows V engines to have reduced weight and size from traditional inline engines without sacrificing any power.
An even more complex variation on the same basic idea as the V engine is the W engine, which is quite fittingly favored by VW, or Volkswagon. Based on the same principle of the V engine, aiming as many lines of cylinders at the same crankshaft as possible, the W engines have several configurations that accomplish this. Two of the most common are three lines of cylinders lined up with one crankshaft, which only kind of looks like a W, and two V engine shapes aimed at the same crankshaft, which looks a lot more like a true W.
One more engine that utilizes creativity to limit size and weight is the OPOC engine. Instead of being lined up, two cylinders are placed directly opposite each other; each cylinder has two pistons inside, and the motion of one directly opposes the motion of the other. This formation allows for extremely efficient turnover of energy, but it’s only practical to use in very small vehicles.
There is one more key element to determining engine types, and that’s air intake. More specifically, it’s if there’s any air intake process at all, or if intake is just allowed to occur naturally.
A naturally aspirated engine is one that has no apparatus for air intake. Most engines are like this, as there is no pressing need to regulate intake; the atmospheric pressure around can handle that for us.
Turbo- or Supercharged Engines
In the instance of high demand on performance, turbo-charged or supercharged engines will sometimes be used to regulate air flow. Both basically decrease pressure inside to pull more air in and drive the engine harder, although the mechanism they use to accomplish this varies.
In the end, no engine is just one thing. You can never say you have a two-stroke engine and expect that to encompass everything. But knowing what you now do, you should be able to pop open the hood on your car and determine at least some aspects of what type of engine it is. Knowing what it is that you’re driving could make all the difference if you’re out on the road and something goes wrong. And even if it doesn’t, knowledge about a tool that makes your life better is always good to have.
- Rank Red – Different Car Engine Types
- Car from Japan – Car Engine Types: Everything You Wanted to Know
- Car Wow – Car Engine Types Explained