What Is Engine Displacement? Pros, Cons, & FAQ
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.
What 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.
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.
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.
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.
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.
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.
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.
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.
Frequently Asked Questions (FAQs) About Engine Displacement
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.
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