Demystifying The Gasonline Engine: A Guide For Newbies

If you are a car driver, chances are your vehicle of choice will have a gasoline engine under the hood. The gas engine, in its basic form, has been around for decades. In fact, it’s been around since the days of the world’s first mass-produced cars.

But if I were to ask you some questions about the gasoline engine, would you know enough about it to answer them? If not, this blog post is for you. Today, I will talk you through the main parts of the gasoline engine, and what they are for.

post2Image via Flickr


The main part of the car’s engine is the cylinder. Each engine can have anything from two cylinders to sixteen! Cylinders can be usually found in one of three formats:

  • Inline (i.e. straight). Many BMW engines have inline six-cylinder engines;
  • Flat (i.e. horizontal). Most Porsche and Subaru engines are flat;
  • V (or “vee”). V6, V8 and V12 engines are common. Some old cars have V4 engines.

Internal combustion process

In each cylinder, a piston moves up and down as part of the internal combustion process. The process has four stages:

  • Intake. The first stage of combustion fills the cylinder with air and gasoline. The piston is at the bottom of the engine at this age;
  • Compression. The piston moves up to compress the air and gasoline inside the cylinder;
  • Combustion. The air and gasoline explodes, thanks to the spark plug. The explosion forces the piston to go down;
  • Exhaust. At this final stage, the exhaust valve opens, and exhaust gases escape through the car’s tailpipe.

The internal combustion process is a cycle that gets repeated thousands of times per minute. You can see how many times a minute that process happens thanks to the engine RPM (revolutions per minute) dial on your dashboard.


All gas engines use spark plugs, as they are essential for the third stage of the combustion process. Combustion occurs at different times in each cylinder to ensure the greatest power.

That can only happen with the help of the engine’s crankshaft. Connecting rods link each piston with the crankshaft. The crankshaft turns in a circular motion.


Some folks might have heard about something called a “sump” before. But what is it, and why is it important in a gas engine?

The sump is a metal container that surrounds the crankshaft. Inside of the sump, oil will get distributed through the crankshaft and towards the top of the engine via the oil pump. But before the oil can reach the top, it has to get filtered first. That’s the job of the oil filter.

The oil that reaches the top of the engine travels back down through special areas of the engine called oil galleries. The process is then repeated over and over again.

According to Marcus from Inchcape Lexus, it’s not unusual to find tiny metal filings at the bottom of the oil sump. Engines get built to certain tolerance levels. Two otherwise identical engines might have slight tolerance differences in their internal parts.

I hope you have enjoyed today’s article. Thanks for reading!

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Published on: August 31, 2014

Filled Under: Cars

Views: 3569

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