What word should you use? Motor or engine? When someone mentions motor oil, you understand they mean engine oil. But a lawnmower has a motor, not an engine. Meanwhile, cars and trucks have motors that differ from the engine that powers the vehicle. So, how do you define engines and motors in a car?
Defining Motor vs. Engine
According to Merriam-Webster, a motor is “any of various power units that develop energy or impart motion.” The power unit can be “a small, compact engine,” an internal combustion engine (especially if it runs on gasoline), and “a rotating machine that transforms electrical energy into mechanical energy.”
In comparison, an engine is a “machine for converting any of various forms of energy into mechanical force and motion.” Relatedly, it can be “a mechanism or object that serves as an energy source.”
The two words have changed their meanings over time. Originally, a motor was something that provided movement or power. Meanwhile, an engine is referred to as a mechanical device–for example, siege engines like catapults and trebuchets are mechanical devices intended for besieging fortifications.
Motor vs Engine In Automotive Context
Historically, “engine” referred to a machine that converts fuel into mechanical power, typically through combustion. A “motor,” on the other hand, was often used to describe devices that convert electrical energy into mechanical motion.
But in the modern automotive context, the distinction has become somewhat blurred. Both terms are now commonly used to describe the power unit of a vehicle, whether it’s an internal combustion engine or an electric motor.
This interchangeability is partly due to the changing syntax of the words and the overlapping functions of these devices.
For simplicity, automotive manufacturers, including GM, use both terms to refer to the same component. This helps avoid confusion, especially as vehicles (hybrids particularly) increasingly incorporate both traditional engines and electric motors.
The interchangeable use of “motor” and “engine” can also be a marketing strategy. For example, “General Motors” itself uses “motor” in its name, reflecting its broad focus on all types of propulsion systems.
Let’s take a closer look at related terms.
Car Motor
Car motors are usually electrical motors. They draw electricity from the alternator or battery for conversion into mechanical energy that can move parts. Motors don’t generate power themselves. Instead, they serve as actuators that turn one type of energy into another.
When you talk about motors, one of the most common examples are electric motors. They’re used in appliances, fans, and industrial machinery.
Based on how their electric current flows, there are two general types of motors: Alternate current (AC) and direct current (DC).
AC Motor
AC motors run on a current that can reverse the direction of its flow and constantly adjust its magnitude. They can regulate the power supply’s frequency and voltage, allowing them to generate high power at low speeds and control speed and torque with high accuracy.
AC motors are widely used in EVs. They enable the high performance of permanent magnet synchronous motors (PMSM) in the latest EVs. PMSM can match gasoline and diesel engines in terms of range and overall performance.
Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.
Pro Tip: Any brushless motor will have the permanent magnets on the rotor with the stator formed of electrical windings that, via electronics, will create magnetic fields that drive the magnet rotor, which spins and provides the torque.
DC Motor
One of the earliest forms of electric motors, DC motors use an electric current that travels in only one direction. They usually draw power from a battery and turn the electricity into rotary motion.;
Most DC motors have sintered copper brushes sliding on a commutator providing power to the spinning wire-wound rotor (armature) so that it uses natural magnetic repulsion from similar poles to spin the rotor within permanent magnets. Starters and power window motors work this way, as do most fan motors.
But there are brushless DC motors that use electronics and a permanent magnet rotor like AC motors. Some GM vehicles use brushless motors for in-tank fuel pumps now.
Modern EVs and many automotive parts still use DC motors for various parts and applications. Hybrid vehicles may have 12-volt brushless fluid pumps for cooling purposes. No matter the operating range, the part can operate at high efficiency. However, they need sophisticated control systems.
Car Engine
Engines generate power and turn it into mechanical power. Most cars and trucks use internal combustion engines (ICE). They burn air-fuel mixture, releasing the energy stored in the fuel as heat, and convert the heat into mechanical power.
Gasoline engines in cars and diesel engines in trucks are good examples of internal combustion engines. You also have jet engines in modern jet aircraft.
Comparing Engine and Motor Components
Another major difference between internal combustion engines and motors is their components. Since engines and motors aren’t the same, their internal parts don’t match.
A car engine has several cylinders with a piston in each cylinder. When the air-fuel mixture burns in the combustion chamber, its heat creates pressure that moves the piston and its respective cylinder. The mechanical energy generated by the process goes to the transmission.
In comparison, a motor has two components: a moving one called a rotor and a stationary one called a stator. The stator usually has metal coils that carry the electric current, although some motor designs have the current go through the rotor.
When a current passes through the stator, the electricity generates an electromotive force that drives the rotor. The spinning rotor produces mechanical power that moves components attached to it.
Other Differences Between Engine vs. Motor
Let’s look at the other ways we can differentiate between an internal combustion engine vs. the motor:
Power Source
Internal combustion engines need fuel. Most vehicles burn gasoline or diesel to produce the heat and pressure that moves the pistons and cylinders when the engine runs.
Motors generally run on electricity. They draw power from the alternator if the engine’s running and from the batteries if you turn the engine off. The motors that drive and brake the wheels of many EVs use electricity.
Lubrication
Engines have multiple moving components that come into contact with each other, generating heat through friction and wearing out their surfaces. They also produce more heat during combustion.
Thus, engines require oil to lubricate their various components. Engine oil reduces friction between surfaces and prevents direct metal-on-metal contact. It also absorbs heat from friction and combustion, keeping the components cool.
Motors also use lubricants. Instead of oil, they use grease with specific characteristics to lubricate their components without interfering with the current flow. If you plan to grease a motor, check your owner’s or service manual for the recommended formula.
Weight
A typical engine weighs more than several electrical motors. An engine has more parts and usually uses heavier materials that increase the weight.
Efficiency
Efficiency is measured by determining the ratio of fuel that gets converted into energy. Engines are less efficient than motors because they waste a higher percentage of fuel during the conversion process.
Noise
Engines make more noise than electric motors because of the loud combustion process and various parts moving during the operation.
Car motors and car engines are two different groups of parts that are indispensable to driving your vehicle safely and enjoyably. Knowing the differences between them can help prevent mistakes during repairs and maintenance.
Keep Reading: Related Posts
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.
