Understanding Engine Displacement


The actual cylinder volume within an engine has an impact on power output and fuel efficiency

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What Is Engine Size?

Engine size or engine displacement refers to how much space (or volume) there actually is in all of the cylinders of the engine combined. This is also called cylinder volume. This is generally conveyed in terms of liters or cubic centimeters, but it has little to do with the physical proportions of the engine block, though. A big engine might only have four cylinders, which means less overall engine capacity. Engineers aren't wasteful though, so you can normally expect the two variables to be symmetrical.

There is also a direct correlation between how many liters an engine can process and engine power/efficiency, meaning more liters = more power. In the past, more cylinders in cars have always meant more power, with V8 and W12 engine configurations found in supercars boasting the highest numbers. However, with turbocharged and supercharged engines now being quite common, inline and flat/H engine or boxer engine setups are able to put out comparable levels of power despite having fewer cylinders.

Engine Liters Ram

How Engine Size Affects Performance

Naturally, this all comes down to how an engine works. By definition, an internal combustion engine is essentially one giant air pump. The pistons inside the block move up and down within the cylinders as the crankshaft rotates. This pushes a mixture of fuel and air into the combustion chamber, which is ignited to release potential energy and produce power. Therefore, more capacity means more fuel for the fire and, consequently, more horsepower. How many cylinders a car has affects capacity and overall potential power outputs.

As mentioned before, though, there are other factors to take into consideration. The cc vs hp argument is no longer as clearcut as it once was. Turbocharging can have a greater impact on performance, although it doesn't actually increase cc of the engine. It can also make the whole system more fuel-efficient since you get more power from a smaller engine. There are also other types of engine trickery to improve performance, such as adding hybrid components and electric motors. But there is a big difference between an engine and a motor that doesn't really factor into this particular discussion.

Engine Size Ram

How To Tell What Size Engine You Have - 2.5L or 2.0 Badges

There is an almost endless list of potential engine sizes for cars. Smaller three-cylinder setups often are 1.2-liter engines. The biggest three-cylinder belongs to the bespoke 1.6L engine built for the GR Yaris which isn't available in the USA. Four-cylinder configurations are generally 2.0-liter, 2.4-liter, or 2.5L engines. If you were wondering "what does the 2.0 badge mean" when looking at all the letters and figures stamped on the back of your car, this is what it is referring to. However, not every manufacturer proudly stamps this on their product, so you may have to figure it out for yourself.

To determine what your actual engine is in terms of displacement, you can use an online calculator or work it out yourself using a formula, which has to do with the number of cylinders and bore vs stroke measurements. Let's take a 2.0L 4-cylinder, for instance, and assume we don't actually know it displaces two liters. You'll use the formula: 𝜋 x bore x stroke x cylinders.

  • 𝜋 - a Pi button should be present on any scientific calculator
  • Bore - this is the diameter of the cylinder and may be referred to as 2(radius)
  • Stroke - this is the distance the cylinder travels in a single rotation
  • Cylinders - this is simply how many cylinders are present within the engine block

Assuming you do the measurements correctly, the final figure should be around 2,000 cc, which translates to 2.0 liters. Alternatively, you could simply search for engine size by VIN, which may be less tedious. You may also find the engine size on the engine block, though this is technically the casting number. You will then need to cross-reference it with an online catalog, such as Kendrick-Auto. Much more simply, you could just check your owner's manual or download a version directly from the manufacturer.

Increasing Engine Displacement Beyond Factory Specifications

It's not unusual to want a car with greater horsepower and the other characteristics associated with massive performance. Unless you want to go out and lay down thousands of dollars on a supercar with one of the most powerful car engines, your options are somewhat limited.

There are some aftermarket ways of increasing the average hp of a car without swapping out the engine. Turbo or supercharging is one way, as is an engine tune-up, but you can actually manually increase the displacement of an engine. This is risky if you don't know what you're doing, though, and it obviously voids any existing warranty on the powertrain. This leaves you with the more hands-on methods:

  • Overboring - This involves using a machine to increase the diameter of each cylinder. This makes the wall of the cylinder thinner, which can lead to complications such as overheating or cracking. Ideally, you should have the cylinders sonic checked to ensure the walls are thick enough to handle the increase in power.
  • Stroke lengthening - The only other way to improve displacement is to increase the length of each stroke. This may be even more labor-intensive than overboring, and it also requires its own set of tools. Ideally, you should try to find a suitable stroker kit in a store or online rather than buying the parts from scrap dealers.
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Is engine displacement the same as CC?

In a sense, yes. CC or cubic centimeters, is one of the most common ways to display an engine's overall capacity. However, most manufacturers use liters, referring to a 2.0-liter four-cylinder, for example, such as the turbocharged unit found on the hot hatch icon that is the Honda Civic Type R.

Why do luxury cars have big engines?

Most manufacturers who produce luxury cars make use of large engines for a few reasons, most pertaining to performance. Ow down torque helps to make acceleration effortless, and the speed that comes with this is a bonus. Using large engines means offering an 'on-tap' experience in a segment where owners must want for nothing. Top-end ultra-luxury cars like the Bentley Continental GT come with either a 4.0-liter V8 or a 6.0-liter W12.

How big is the average engine?

This depends on the segment - small passenger cars don't need large displacement engines, while hardcore off-roaders and workhorse pickups need much larger engines to get the work done. Small hatchbacks and sedans generally have 1.4L, 1.5L, or 1.6L four-cylinder engines, some even boasting 2.0L or 2.5-liter power plants.

How do you increase engine displacement?

There are only two ways to improve engine displacement without replacing the entire block. You can either enlarge the cylinder diameters through boring or increase the stroke of each cylinder with a stroker kit.

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