(Updated on January 13, 2021)
While checking your oil have you ever wondered what actually is under that engine cover? What do those parts do? How does an engine really work?
Underneath that beautiful (in some cases) engine cover lies a wonderful piece of engineering. The modern-day automotive engine is capable of some wonderful feats.
Let’s pull back the curtain and take a look at some of the most common parts that reside in the engine bay of today’s vehicles.
Top 5 Important Parts of a Car Engine
1) Engine Block
The engine block is the back bone of the car engine. It provides a housing that contains the pistons, crankshaft, and sometimes the camshaft. Not only does the engine block house items, it also contains a variety of machined surfaces.
Holes that are machined in the block are known as cylinders and an engine can contain anywhere from 4-16 cylinders depending on size. Most vehicles on the road today have either four, six, or eight cylinders.
An engine block can be configured in a multitude of ways. An inline engine has, as you can imagine, has its cylinders located in a line. A “V” engine holds the cylinders in a V configuration similar to the letter that bears its name (ie: V8).
Other engine configurations include: straight or inline, flat, boxer, W, and even the Wankel (rotary) type made famous by Mazda.
Pistons are what transfer the energy that is created during the combustion cycle and transmits it to the crankshaft. This energy transfer, simply put, is what effectively propels our vehicles.
Pistons contain piston rings that ensure proper sealing as well as oil control. Pistons on many modern vehicles also are coated in a material that prevents friction allowing the pistons to last longer.
These pistons travel up and down in the cylinder twice during each revolution of the crankshaft. This means an engine rotating at 2500 RPM, the pistons are travelling up and down 5000 times per minute.
The crankshaft rides in the lower section of the engine block and rides in what is called crankshaft journals. The crankshaft is a finely machined and balanced component that is connected to the pistons through what is known as a connecting rod.
The crankshaft takes the up and down movement of the piston and converts it to rotary motion, or reciprocal motion. The crankshaft rotates at engine speed.
Depending on the style of engine the camshaft can be located either in the block or in the cylinder heads. When the camshaft is located in the engine block it is known as a cam in block engine, however, most modern engines have the camshaft located in the cylinder heads.
These modern engines are known as DOHC (Dual Overhead Camshaft) or SOHC (Single Overhead Camshaft). The main job of the camshaft is to take the rotary motion of an engine and convert it to up and down movement.
This up and down movement controls the movement of the lifters which in turn moves the pushrods, rockers, and valves. The camshaft is supported by a series of bearings that are lubricated in oil to ensure long engine life.
5) Cylinder Head
While the above components may be considered the heavy lifters in the car engine the cylinder head is much more precise. The cylinder head contains many items including valve springs, valves, lifters, pushrods, rockers, and sometimes even camshafts.
The cylinder head also controls passages that allow flow of intake air into the cylinders during the intake stroke as well as exhaust passages that allow the removal of exhaust gases during the exhaust stroke.
The cylinder head is attached to the engine through what is called cylinder head bolts, the area sealed between the two is sealed with a head gasket. Head gaskets can be a common source of engine issues.
See Also: History of the Subaru Head Gasket Issue
The above components are the main components of a car engine. The car engine also contains many other parts, hoses, wires, and fasteners to hold everything together. Bearings and oil throughout the engine prevent premature wear, and a timing belt or chain ensures all components function together at the correct time.
Although the modern automotive engine can seem daunting, hopefully you can now gleam a little bit more information on how all these components function together in what is known as the modern car engine.