A guide to car engine types
Although most of us are obsessed with the appearance of a car, non-oilers rarely pay attention to its most important part – the engine.
The internal combustion engine comes in different shapes and sizes, each with its own set, advantages and limitations. With that in mind, we’ve put together a little list explaining all the common engine types so that next time you don’t have to get confused when someone says their car has a “V6” or “boxer” engine.
We’ll skip electric motors for this one, simply because there are only a handful of electric vehicles in Bangladesh and anyone looking to get one probably already knows more than we do.
The most common type of engine used in modern cars, inline or “straight” engines are types of engines where all the cylinders are placed vertically in line, or one behind the other.
The common layout includes 3, 4 or 6 cylinders, while rarer 5 or 8 cylinder configurations also exist. Small 3- or 4-cylinder lines are efficient, relatively simple, and cheaper to manufacture, making them the preferred choice of automakers for compact, fuel-efficient cars.
However, these designs lack the power-generating capabilities of more complex engines and, due to their straight-line design, become less space-efficient as more cylinders are added.
To circumvent the length problem of inline engines, engineers came up with the “V” layout. In such a configuration, an equal number of cylinders are placed parallel to each other, inclined at an angle and connected to a single crankshaft. This resulting shape is largely similar to the English letter “V”, hence the namesake.
V6, 8, 10 and 12 cylinder engines are the most common, although oddities such as Lancia’s V4 make it into the production range from time to time. Compared to inline engines, the V-design is much more complicated, but can accommodate double the cylinders in half the space. The extra cylinders can be used to produce more power or make the engine run smoother, making them ideal for performance and luxury cars.
Due to the large number of cylinders, these engines also have a large displacement, usually from 2000 cc and above, which makes V-engined cars a rare sight on the roads of Bangladesh.
Flat engines, also called horizontally opposed and sometimes incorrectly called “boxer” (which is a subtype), are engines where the cylinders sit horizontally flat against each other. A flat engine retains the compactness of a “V” engine but is much shorter in height, resulting in a lower center of mass. And because the pistons move against each other, they cancel out a lot of their own vibrations, making the engine run smoother.
On the other hand, these engines are much wider. The wide configuration helps with cooling (more metal surface) but makes it difficult to install on most cars. These types of motors are also more expensive and complicated to build, making them a somewhat unpopular choice.
However, Subaru is an exception to this though. Their entire line of vehicles uses the boxer engine exclusively and is only offered in all-wheel drive, with the sole exception of a two-door RWD sports sedan made with Toyota. Another automaker that uses the flat engine is Porsche, whose Boxster nameplate is widely regarded as one of the finest sports cars ever made.
All of the engines on this list use multiple cylinders to drive a single crankshaft, but this one doesn’t, it doesn’t.
Designed by a certain Felix Wankel, a German with no formal background in mechanical engineering (who also happened to be an enthusiastic member of the Nazi Party), the rotary engine uses a triangular rotor (sometimes called a “dorito” because of its shape) to convert rotational pressure. In much simpler terms, the rotor walls compress air against the engine block wall, creating the same effect of an engine cylinder in a much smaller space.
Rotary motors are simpler, smoother, and offer plenty of power for their size. But they are also not very fuel efficient and tend to be “dirtier” for the environment than others.
Many car manufacturers tried to work with the rotary engine, but all abandoned their designs for one reason or another. Mazda was the most successful of all attempts, which for a time embraced the rotary just as Subaru embraced the boxer. Their rotating swan song is the RX-8 sports car, several of which can be seen in Bangladesh.
That being said, Mazda is reportedly working on a new rotary successor to the RX-8, so we may soon see a return of the rotary.
In addition to these layouts, there are other much wilder engine designs. There’s the “VR” layout, which is basically a v-engine designed to fit inside an inline engine block. Two of those best “W” engines of such a design would be the W16 used exclusively by multimillion-dollar Bugatti hypercars. There are “X”, “H” and U engine types, but these are mainly used for military and marine vehicles.