What is a Naturally Aspirated Engine?

A naturally aspirated engine uses atmospheric pressure to drive air intake, as opposed to forced induction through a turbo or supercharger.
Written by Patrick Price
Reviewed by Melanie Reiff
Naturally aspirated engines are a form of internal combustion engine that use atmospheric pressure to drive the air intake process required for operation. 
A naturally aspirated or “naturally breathing” engine is one that relies only on normal atmospheric pressure to take in air. Many recent cars are being built standard with superchargers or turbochargers instead, which trade natural aspiration for forced induction. 
While forced induction in these new cars provides better fuel economy, cleaner emissions, and increased horsepower, natural aspiration is more common in sports cars for its easier maintenance, improved reliability, and no turbo lag. 
To help you understand what naturally aspirated engines are, how they work, and what benefits they offer over turbocharged engines,
—the expert for
car insurance
savings and
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knowledge—has prepared this guide. 

How does a naturally aspirated engine work?

Internal combustion engines—sometimes called “petrol engines” or “cylinder engines”—are the most common engines in the automotive world. They include traditional gasoline-powered systems as well as diesel engines.
They create horsepower through a series of controlled explosions inside the engine
These engines need a combination of fuel and air to create each explosion. The fuel is provided by fuel injectors, which are connected to the gas tank. The air comes one of two ways: through forced induction or through natural aspiration
In natural aspiration, air intake occurs similarly to respiration in your lungs. It begins when you start your car and the pistons are drawn downward. This creates a partial vacuum. The surrounding air then rushes in to fill that vacuum—at which point it can be used for combustion. 
The combustion then drives the pistons back up, and the cycle repeats. The repetitive motion of the pistons is transferred to the crankshaft via connecting rods. The crankshaft, in turn, transfers the motion to either the front axle, rear axle, or both (if you have all-wheel drive). 
The end result is an engine that rumbles, wheels that roll, and a car that takes you where you need to go—all through the magic of the mechanical breathing system known as natural aspiration. 
Key Takeaway Naturally aspirated engines take in air by a partial vacuum created when the pistons are drawn downward. It is then used for combustion, and the process repeats as you drive. 

Benefits of a naturally aspirated engine

Natural aspiration (abbreviated as NA or N/A) used to be the primary form of internal combustion. Later, various forms of forced induction were developed—originally for their superior horsepower and later for their improved fuel efficiency and reduced exhaust gasses. 
Today, more and more cars use turbochargers and superchargers (which use forced induction, not natural aspiration) as the need to limit our automotive emissions becomes more severe.
Still, the old-school naturally aspirated engines have not died out completely—they’re kept alive because they offer a few benefits over forced inductions systems. The benefits of naturally aspirated engines include:
  • NA engines are easier to clean, repair, and maintain
  • It costs less to manufacture NA engines
  • There are fewer parts involved in an NA engine and less strain is put on their various components—making them much more reliable
  • There’s less likelihood of a NA engine overheating
  • Since they do not have turbochargers, NA engines don’t suffer from turbo lag—meaning they have a more direct throttle response and accelerate immediately 
  • Due to their decreased strain on engine components, NA engines often have a higher redline, which is the maximum safe RPM range for a car  

Naturally aspirated vs. turbocharged engines

So, what’s the alternative to natural aspiration? As has been mentioned, the other common form of air intake is called forced induction. It involves any process by which air is forced through the engine at a higher than normal rate.
If natural aspiration is like breathing, then forced induction is like wearing an oxygen mask. 
The first forms of forced induction were called superchargers, which usually worked by drawing some of the power generated by the crankshaft and using it to push air through the engine.
Superchargers offered substantial improvements to a car's horsepower, but little (if any) benefits to fuel efficiency—and they weren’t widely used except as aftermarket modifications. 
Then along came turbochargers. These inventions use the energy from the engine’s exhaust gases to spin a turbine—partially cleaning the car’s emissions at the same time.
The turbine then drives more air into the engine—which boosts its horsepower without increasing its fuel consumption, resulting in greater overall fuel economy. 
At first, superchargers and turbocharges were mainly used in muscle cars and supercars by drivers looking to boost their power. Now, they have become the dominant form of engine.
However, some automotive manufacturers, like
, still primarily use naturally aspirated engines. NA engines are also very common in race cars, due to league rules for Formula 1, NASCAR, and other racing organizations. 
Key Takeaway While many cars now intake air through forced induction, some automotive manufacturers still use naturally aspirated engines.  

Car lineups with naturally aspirated engines 

Turbochargers may be the more common form of air intake today, but there are still plenty of cars out there with naturally aspirated engines—and not just race cars either.
Plenty of leading manufacturers have whole lineups featuring natural aspirations in everyday-use SUVs, sports cars, and sedans. Here are just a few examples of cars with naturally aspirated engines: 
These are only the models with current iterations that offer natural aspiration. Many other model types, such as the Honda Civic Type R, offered natural aspiration in past years—just not in the current lineup. 
Keep in mind that many of these models come in various
trim levels and packages
, only some of which are naturally aspirated. But all the vehicles you see listed are at least offered with natural aspiration—and there are plenty more that aren’t included on our list. 

Find hassle-free car insurance

Whether you like your engine’s aspiration natural or turbo-assisted, you’ll still need to get it insured. And drivers with turbochargers and those without can at least agree on one thing: searching for reliable yet affordable
car insurance
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