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What Is Engine Displacement? What You Need To Know!

man checking car engine

Engines are extremely complex machines, with numerous complex calculations coming into play together to determine how your car runs. Engine displacement is one of those measurements, contributing to engine power and fuel usage. However, what exactly is engine displacement, and how does it affect your car? Let’s find out the answers to those questions and other relevant info below.

divider 1What Is Engine Displacement?

Engines produce power by displacing air, mixing it with fuel, and igniting it in a controlled way. Engine displacement is a measurement describing how much air an engine can displace, based on a few variables. Primarily, the cylinder volume, crankshaft stroke, and number of cylinders. More cylinders and larger cylinders mean more air, and the distance pistons travel will also determine how much air is displaced.

Higher engine displacement generally means more power while using more fuel, while lower displacement means less power and better fuel efficiency. This is why smaller engines tend to have better gas mileage than large engines. Engine displacement is also used by many countries to determine taxation of vehicles—the US does not, but the UK does. However, cars with higher displacement in the US are also more likely to be more expensive because they’re more powerful.

Displacement is simplified into terms like cc’s (cubic centimeters), cubic inches, and liters. For example, 1000cc vehicles are less powerful than 1400cc vehicles. On the other hand, 5.7 liters describes the cylinder volume. Other terms, like V6, V8, and V12, describe how many cylinders a car has, with more cylinders meaning more powerful cars.

man checking car engine
Image By: Me dia, Shutterstock

How Is Engine Displacement Calculated?

Engine displacement is calculated by multiplying the cylinder bore’s area by the crankshaft stroke length, then multiplied by the number of cylinders. This gives you the total volume of air within the engine cylinders, which is your engine displacement. The exact numbers and measurements vary in these calculations. Sometimes they’re in cc’s, cubic inches, or liters.

Is Engine Displacement Really That Important?

Yes, it’s very important when determining how much power a car will produce, but it’s not the only factor. In decades past, car enthusiasts thought that displacement was the main thing affecting a car’s power. Sadly, that’s just not true.

The things that work hand in hand with displacement are the cylinder head, compression ratio, and camshaft design. If a subpar compression ratio or engine parts are used, high displacement won’t do much. Cars with huge engines debuted as early as 1910, but they offered mediocre power that today’s compact sedans surpass with ease.

Other minor tweaks that improve power are variable valve timing, turbochargers, and modern fuel injection techniques. Combined with high-quality engine components and large cylinders, these technological advances are getting very good at squeezing every drop of power out of an engine.

If you’re looking to boost the power of your car, higher displacement isn’t the only answer. You should also consider swapping out your camshaft, doing some cylinder-head work, and improving your compression ratio.

jet engine under maintenance
Image Credit: PublicDomainPictures, Pixabay

How Does Engine Displacement Affect Car Performance?

We mentioned that engine displacement is one of the main things that drives a car’s performance. Performance can be delineated into a few categories: namely, the engine’s power, acceleration, and efficiency. Let’s discuss those in more detail below.

Engine Power

Higher displacement engines can go faster than low displacement cars because they displace more air and fuel. Higher displacement engines are more labor intensive than smaller engines too, which ultimately makes them more expensive.

We should also talk about turbochargers. Turbochargers compress the air in your cylinders, which makes your engine produce more power. They’re typically expensive but can help less powerful cars compete with high displacement cars. The main advantage of turbo engines is that they run like regular engines, but you activate the turbo for a powerful speed boost.

pouring oil to car engine during oil change
Image Credit: r.classen, Shutterstock

Acceleration

High displacement engines take longer to accelerate than low displacement engines but ultimately reach a higher top speed. Low displacement revs faster but can’t match the top speeds of larger engines. This widely varies based on modifications like turbochargers and other improvements to the engine.

Efficiency

Lower displacement engines use less fuel than large engines, meaning it’s cheaper to fill up their tanks. Also notable is that smaller engines wear out faster than large engines. That happens because smaller engines need to rev more to produce the same results as a larger engine.

However, smaller and fewer cylinders mean your repair and maintenance costs will be lower than with large cylinders. High displacement cars tend to cost more because they offer more power, which contributes to high repair and maintenance costs.

toyota hybrid engine
Image Credit: PhotoMIX-Company, Pixabay

Advantages of Low and High Displacement Engines

It’s easy to assume that high displacement is better than low displacement, but that’s not necessarily true. Both have their place in various types of cars on the market today, and it’s important to know the strengths of each engine type.

Advantages of Low Displacement Engines
  • Fast acceleration
  • Can be modified to perform better
  • More fuel-efficient
  • Compact size allows for more space in other parts of the car
  • Cheaper to manufacture
  • Lightweight
  • Cheaper to repair and maintain
  • Tend to have higher resale value than larger engines
Advantages of High Displacement Engines
  • More power
  • Lasts longer than a small engine
  • Produces more torque
  • Unique punchy performance
  • Typically good at towing
car engine of an orange car
Image Credit: Photoman, Pixabay

Disadvantages of Low and High Displacement Engines

Low and high displacement engines have their own unique weaknesses too. Before committing to a small or large engine, you should familiarize yourself with its cons. Let’s check out some of those next.

Disadvantages of Low Displacement Engines
  • Lower power
  • Shorter lifespan if modified
  • Takes longer to get up to speed
  • Weaker engine noise
  • Needs to be used at high RPMs, potentially wasting gas
Disadvantages of High Displacement Engines
  • Heavy
  • Limit space in other parts of the car
  • Lower resale value
  • Lower fuel economy than small engines
  • More exhaust emissions
  • Engine size can negatively impact handling

divider 7Frequently Asked Questions (FAQs) About Engine Displacement

  • Should I aim for low or high engine displacement?: There’s no cut-and-dry answer as to which is better because it depends on what you’re looking for in a car. Higher displacement uses more fuel to get more power and speed, while smaller engines use less fuel for relatively weaker performance. If you want power and speed, go for high displacement, while low displacement is great if you want to save on gas and don’t need a racecar.
  • How do you increase engine displacement?: There are two main ways to increase engine displacement, but both are fairly difficult to do. You can either bore the cylinders to increase their diameter or use a stroke kit to increase the crankshaft stroke. Both have their pros and cons, but boring is typically the best way to instantly increase engine displacement.
  • Can you reduce engine displacement?: Reducing engine displacement is trickier than increasing it but is still perfectly doable if you’re determined enough. You can either reduce the bore size of your cylinders or reduce the crankshaft stroke. Reducing the stroke, in this case, is the best way to go, because decreasing the bores is very difficult and usually not worth it.

divider 1Conclusion

People used to think that engine displacement was the main thing affecting engine performance, but we know that’s not true today. Low displacement has its place in more efficient cars, while high displacement is perfect for the realm of sports and luxury cars. If you’re interested in changing displacement, there are two major ways that require some preparation and experience.


Featured Image Credit: Me dia, Shutterstock

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