Car and Bikes Engine Configurations
After discussing the basic functionality of a 4-stroke internal combustion engine in a previous blog post, I’ll talk about the various different engine configurations found in modern vehicles.
This is the most easy to identify because of its shape. In this configuration the cylinders are separated in two different banks forming a ‘V’ shape like the below image of a BMW V8 engine (where 8 stands for the number of cylinders, 4 on each side).
In most cases, the ‘V’ angle is either 60 or 90 degrees but the changes in this angle have effect on the engine’s performance and general operation. Additionally, these engines are the most common among 2 cylinder chopper style motorcycles.
And for that matter they are known as V-Twin engines. The main characteristic of such engines is their smooth operation because of the equally distributed forces on the crankshaft. On the downside they are usually available only in expensive cars with large displacements and from a mechanical point of view, they require more space in comparison to other configurations but they are easy to maintain. Also, they are the best option regarding temperature since the distance between the two banks decreases the temperature of the engine’s block. Finally, the opposing movement of the pistons usually results in a very unique and easy to recognize exhaust sound.
This is a common configuration among various models in today’s industry in both cars and bikes.
Such configurations are easy to maintain and require less space than the previously described ‘V’ engines. Their naming is usually like this “straight-XX” where ‘XX’ is replaced with the number of cylinders. For example, in the above picture you can see a straight-4 engine of a BMW. According to wikipedia, the straight-4 engines are the most common in most car manufacturers. Of course, this is also very common among almost all motorcycle brands.
Here you can see the straight-twin (most commonly referred as parallel-twin) engine of a Yamaha TDM-900. Such twin piston engines have their cylinders inline and both pistons perform the same movement (this is why it’s called parallel) even though straight (4 cylinders and above) engines don’t do this. Specifically, in the TDM-900 case the crank has a 270 degree angle. Because of this angle, the engine will ignite the mixture in every engine revolution which is new in comparison to classic straight model that will fire the spark plugs every two revolutions. This even firing can result in greater torque. Also, because of this feature many Japan manufacturers use a single spark for both cylinders. Another advantage of such architectures is the lack of vibration because of the uniform movement. Finally, even though the engine feels smooth because of the massive piston movement the exhaust sound is usually very aggressive and heavy. However, this doesn’t apply to other straight engines which have normal vibration and they don’t produce that sound.
As its name implies, it’s a ‘W’ shape engine which looks something similar to this:
Here we have three (or four in some cases) cylinder banks in a ‘W’ shape. Using either the design of an inline and a ‘V’ engine (resulting in three banks), or two ‘V’ engines which gives us four banks. The main advantage of these engines is their ability to have great performance in the whole range from low to high RPMs. This is done because each bank has separate timing on its camshafts and consequently, the crankshaft will always receive enough torque to provide the required horsepower. Although recently Volkswagen released some car models using this configuration, this type of engine was very common in aircrafts since early 1900.
Probably the most common configuration in Subaru cars and BMW bikes. Have a look at the below cutaway image of a Subaru engine to get an idea.
Its name derives from the cylinders’ position. Its main disadvantage is the usually larger engine block but on the upside the low center of gravity provides great stability and because of its design both sides have the same compression stroke timing. Because of this position, this engine configuration produces some heavy and aggressive exhaust sound but it has extremely smooth operation (the crankshaft receives more smooth torque from the connecting rods) in the whole RPM range (from low to high). From a technician’s point of view they are usually difficult to maintain in comparison to common inline ones. Now, on the motorcycle world these engines are very common too.
Like the above BMW flat/boxer-twin engine the 2-cylinder engines have the same characteristics as the rest of the boxer engines. Another great advantage is their temperature level (similar to the ‘V’ ones) which is much lower than other configurations having cylinders close to each other. This means that such engines require smaller cooling systems.
There are few more configurations but these are used in like the 99% of nowadays cars and bikes.
Once again, all the images and photos were found using Google Images, none is mine.