Final answer:
An engine without a turbocharger or supercharger is called a 'naturally aspirated' engine. These engines rely on atmospheric pressure for air intake and are simpler and potentially more reliable than forced induction engines.
Step-by-step explanation:
An engine without a turbocharger or supercharger is typically referred to as a ‘naturally aspirated’ engine. In a naturally aspirated engine, air is drawn into the combustion chamber solely by atmospheric pressure and not by any form of mechanical air induction system. The absence of forced induction means that these engines rely on the oxygen in the atmosphere to mix with the fuel for combustion. This contrasts with turbocharged or supercharged engines, which use a turbine or a compressor to force more air, and consequently more oxygen, into the combustion chamber, often leading to increased power output.
Naturally aspirated engines are simpler in design and typically have less complexity and fewer parts than engines with forced induction. Because of this simplicity, naturally aspirated engines can be more reliable and easier to maintain, which might be important to some consumers. They also provide a linear power delivery, which is often preferred by driving enthusiasts for the predictability and control it offers.