Unless you’re a car geek, you probably don’t think all that much about your car’s engine — until something goes wrong under the hood, of course, at which point you curse and hope a squirrel’s not lodged under the hood. With a trouble-free engine, you do the weekday commute and the weekend outings wholly unthinking of the devices at work in that mechanical miracle under the hood. That workhorse, the modern combustion engine, is a technological marvel that befuddles most drivers, and terms like “piston” and “crankcase” register to some as obscure nomenclature.

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Car engine names can be confusing — inline four, inline six, boxer, V6, V8, V12 — and these days the waters are muddied even more as clean-burning diesel engines and high-output 4 cylinders infiltrate the market. So, here’s a quick primer on how a combustion engine works and a rundown of the various types of combustion engines available in mainstream consumer automobiles.

A Glossary of Terms

Carburetor: a device that mixes air and fuel in the proper ratio for combustion. The system is mechanical and not electronic (like fuel injection or direct injection engines), and it is less efficient.
Crankcase: part of the engine block that houses the crankshaft. Usually a single-piece or two-piece construction of aluminum or cast iron.
Crankshaft: the engine component that provides rotational motion when combustion occurs, causing the pistons to move within the cylinder to the connecting rod.
Cylinder: the portion of the engine block that houses the piston and connecting rod, and the location where combustion occurs in gasoline automobiles.
Direct Injection: a method by which gasoline is highly pressurized and injected into the cylinder’s combustion chamber (unlike fuel injection, where gas is injected into the cylinder’s port).
Harmonic Balancer: also known as a dampener, a circular device made of rubber and metal and attached to the front of the crankshaft to help absorb vibrations and reduce crankshaft wear and the likelihood of failure. It reduces engine harmonics that occur when multiple cylinders move along the crankshaft.
Piston: a component that’s housed within the cylinder walls and secured by piston rings. It moves up and down during the four-cycle process providing force when combustion moves it and the connecting rod to the crankshaft.
Rev Matching: technology in manual transmission cars that utilize sensors on the clutch pedal, gear shift, and transmission, sending signals to the Electronic Control Unit (ECU). The ECU will blip the throttle automatically if engine rpms fall below that of the high gear shift when the clutch is depressed for too long. Rev matching also occurs during the downshift, bringing rpms higher to match the lower gear. This reduces wear on the engine and provides smoothness during the shifting process.
Torsional Vibration: vibration that occurs due to rotating shafts within a car.

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