Car Engine Explained: Parts, Types, Common Problems & Future Trends

Suck, squeeze, bang, blow. This funny little phrase is often used to explain how an internal combustion engine works. Most modern car engines follow a four-stroke cycle where the intake stroke pulls in the fuel and air mixture, the compression stroke squeezes it, the power stroke ignites it, and the exhaust stroke pushes out the burnt gases.

While that sums it up simply, the real story goes much deeper. Understanding the main car engine parts and their role in this cycle gives a clearer picture of how the engine runs. By looking closely at the different engine components and learning about the engine parts and functions, you can appreciate the clever engineering that keeps your car moving.

What is a Car Engine?

A car engine is often seen as the heart of a vehicle because it converts fuel into mechanical energy that makes the car move forward. It is the main power source, and most cars on the road still rely on petrol or diesel internal combustion engines. At the same time, electric and hybrid engines are quickly becoming more common.

To really understand how a car engine works, it helps to look at the main car engine parts and see how they come together. Each of the engine components plays a specific role, and learning about the engine parts and functions gives you a clearer picture of the engineering behind your car.

How Does a Car Engine Work?

Getting a sense of how the engine works under the bonnet is useful for every car owner. It helps you make smarter decisions about maintenance and also makes it easier to understand technical terms like cubic capacity, inline engine, or liquid cooling when going through a car’s spec sheet. At the core of most cars on Indian roads is the internal combustion engine (ICE), which runs on the four-stroke cycle. This cycle converts fuel into mechanical energy using different car engine parts and components, each playing a vital role.

Let’s take a closer look at how both petrol and diesel engines work in this cycle.

How a Petrol (gasoline) Engine Works

A petrol engine, also called a gasoline engine, is one of the most common types found in cars today. It generally works on the Otto cycle, which is the classic four-stroke process that relies on engine components like pistons, valves, spark plugs and the crankshaft to generate power. In simple terms, the Otto cycle focuses on producing smooth performance and good power delivery.

1. Intake stroke – The intake valves open, the piston moves down, and the fuel–air mixture enters the cylinder.
2. Compression stroke – The valves close, the piston moves up, and the mixture gets compressed, building up pressure.
3. Power stroke – The spark plug ignites the compressed mixture, causing a controlled explosion. This pushes the piston down, creating energy that turns the crankshaft.
4. Exhaust stroke – The piston moves up again, pushing out burnt gases through the exhaust valves.

This continuous cycle, supported by different engine parts and functions, produces the smooth power delivery you feel when driving. Petrol engines are usually lighter, quieter and well-suited for city driving.

In some modern hybrid cars, you’ll find petrol engines running on the Atkinson cycle instead. This variation of the four-stroke process keeps the intake valves open for slightly longer, which improves fuel efficiency by reducing pumping losses. While Atkinson cycle engines make a bit less power than a traditional Otto cycle engine, the trade-off is higher efficiency, a perfect fit for hybrid cars where the electric motor can assist with extra power when needed.

How a Diesel Engine Works

Diesel engines may look similar to petrol engines in design, but they operate on the Diesel cycle and rely on different engine components and processes to ignite the fuel. Unlike petrol engines, they do not use spark plugs. Instead, they depend on the heat generated by very high compression inside the cylinder.

This is possible because diesel fuel has a higher auto-ignition temperature and ignites when exposed to the intense heat created by compressing air. During the power stroke, the injector sprays diesel directly into this hot, compressed air, causing instant combustion without the need for a spark.

1. Intake stroke – The piston moves down, drawing only air into the cylinder.
2. Compression stroke – The air is compressed much more than in a petrol engine, raising its temperature significantly.
3. Power stroke – Diesel fuel is injected directly into the hot compressed air. The heat causes it to ignite instantly, forcing the piston down to produce power.
4. Exhaust stroke – The piston pushes the burnt gases out of the cylinder, making it ready for the next cycle.

This property of diesel, combined with strong car engine parts designed to handle higher pressures, allows these engines to deliver better fuel efficiency, higher torque, and durability, making them popular in heavy vehicles and long-distance cars.

With both petrol and diesel engines, the clever combination of engine components, from pistons and valves to fuel injectors and the crankshaft, keeps the cycle running smoothly.

Main Car Engine Parts and Their Function

1. Engine block

The engine block houses the cylinders and various components that form the engine's core. Typically made from cast iron or aluminium alloy, the engine block is the solid outer shell of an engine that provides the structural integrity required to withstand the forces generated during combustion.

2. Cylinder

It is inside the cylinders that the combustion process occurs. Cylindrical chambers are precision machined into the engine block. They can vary in numbers, affecting the engine's power and overall cubic capacity. Common configurations in cars include three, four, six, and eight cylinder engines.

3. Cylinder head

The cylinder head sits atop the engine block, sealing the cylinders and housing the valvetrain, spark plugs, and the camshaft.

4. Valves

Valves regulate the flow of air and fuel into the cylinders and exhaust gases out of the cylinders. Intake valves allow the air-fuel mixture to enter the cylinder, and exhaust valves let the burnt gases exit the cylinder. Number of valves per cylinder can vary from two to five.

5. Camshaft

The camshaft controls the opening and closing of the engine's valves. It is synchronised with the crankshaft via a timing belt or chain. The camshaft ensures that the intake and exhaust valves open and close at precise intervals during the engine's combustion cycle.

6. Pistons

Pistons are cylindrical blocks that move up and down within the cylinders. They are encased within piston rings to maintain optimum pressure within the cylinders.

7. Connecting rods

Connecting rods serve as the link between the pistons and the crankshaft. They play a vital role in converting the linear motion of the pistons into the rotational motion of the crankshaft.

8. Crankshaft

The crankshaft is a long, rotating shaft located at the bottom of the engine block and cylinders. It converts the linear motion of the pistons into rotational motion, which drives the gearbox that ultimately drives the vehicle's wheels.

9. Timing belt/chain

The timing belt or chain synchronises the rotation of the crankshaft and camshaft. This synchronisation is crucial for ensuring that the valves open and close at the correct times relative to the piston's position.

10. Spark plugs

Spark plugs ignite the air-fuel mixture within the cylinders. They create a spark that triggers combustion at the right moment during the compression stroke. Most engines use a single spark plug per cylinder, with some manufacturers opting for two as well.

11. Fuel injectors

Fuel injectors are tiny spray nozzles that are electronically controlled and deliver precise amounts of air/fuel into the cylinders.

12. Exhaust system

The exhaust system expels burnt gases from the engine. It includes components like the exhaust manifold, catalytic converter, and muffler. This system not only removes exhaust gases but also reduces harmful emissions and noise.

13. Lubrication system

The lubrication system ensures an adequate supply of oil to all moving parts within the engine, to minimise friction and wear. It includes the oil sump/pan, oil pump, oil filter, and various oil passages that distribute engine oil.

14. Cooling system

The cooling system prevents the engine from overheating. It circulates coolant through the engine block and cylinder head, absorbing heat and dissipating it through the radiator. The system includes components like the water pump, thermostat, and radiator.

15. Engine management systems

Modern engines are controlled by sophisticated engine management systems that optimise performance, efficiency, and emissions through Electronic Control Units (ECUs). These ecuS take inputs from various sensors that monitor engine parameters.

16. Flywheel

Attached to the crankshaft, it stores rotational energy and smooths out the power delivery between combustion strokes. In manual cars, it also connects with the clutch.

17. Gaskets

Especially the head gasket, which seals the gap between the engine block and cylinder head to keep coolant, oil, and combustion gases separate. People often hear of “blown gaskets,” so including this helps readers connect.

18. Turbocharger

Since many modern cars use turbo-diesel and turbo-petrol engines, mentioning how a turbo forces more air into the cylinders to boost power and efficiency would add depth.

19. Intake system / Air filter

Air intake and its filter are crucial as engines need clean, dust-free air for combustion. Without this, engine life shortens drastically.

20. Starter motor & Alternator (basic electrical system link)

The starter motor cranks the engine to get it running, and the alternator generates electrical power once the engine is on. This shows how mechanical and electrical parts work together.

21. Glow plugs (for diesel engines)

Since you’re already explaining the diesel cycle, it’s worth noting that diesel engines use glow plugs to preheat the combustion chamber in cold starts, but not used in regular running.

Different Types of Car Engines

There are a few common engine layouts you will see in cars: inline, V, flat (boxer), and increasingly, hybrid powertrains that combine an internal combustion engine with electric motors. Each layout uses the same basic car engine parts, but arranges them differently to meet goals like packaging, cost, smoothness and performance. Picking the right layout often comes down to what the car is designed for, city use, long-distance cruising, towing or sporty driving.

Inline Engines

Inline engines, also known as straight engines, arrange all cylinders in a single row. You’ll often see these in small and mid-sized cars because they’re simple, compact, and easy to service. They use common car engine parts in a neat, linear layout, just one cylinder head and fewer extra components, which keeps maintenance hassle to a minimum.

Inline-3 engines are increasingly popular, especially in budget models, because they cut manufacturing and maintenance costs. Inline-4 engines are now more commonly found in premium and entry-level luxury cars, as the lower end of the market shifts to smaller engine options.

Inline-5 engines remain rare but have a strong cult following. You’ll find them in performance models like the Audi RS3 and TT RS, the Volvo D5 diesel, and the Ford Focus RS. These engines strike a unique balance between smoothness, character and compactness.

Inline-6 engines are known for their exceptionally smooth power delivery because they achieve both perfect primary and secondary balance, a rare trait among engine types. You'll find I6s in luxury sports sedans, commercial diesel engines, and premium SUVs. They offer low vibration and strong torque, though their length makes them harder to fit transversely in modern compact engine bays. This is why most cars opt for a V6 layout instead of I6.

Inline engines are known for their smooth operation and ease of maintenance. Most common engines are three or four-cylinder arrangements.

Here are the advantages and disadvantages of inline engines:

V Type Engines

V engines have their cylinders split into two banks, placed at an angle to form a "V" shape. This layout makes the engine shorter and more compact compared to inline engines, which is why it is popular in larger, more powerful cars. By arranging cylinders this way, manufacturers can fit more of them into a tighter space, boosting performance without making the engine too long or bulky.

V engines are found in many configurations, each serving a different purpose:

• V2 engines – Seen mostly in motorcycles and some small cars in the past. They are simple, compact and deliver a strong low-end punch but are less common in cars today.
• V3 and V4 engines – Quite rare, but some Japanese and European manufacturers experimented with them in bikes and compact cars. They never became mainstream because inline-3 and inline-4 were cheaper and easier to build.
• V5 engines – Volkswagen famously used a narrow-angle V5 in some of its cars, but very few companies adopted it. It sat between a four- and six-cylinder, but market demand was limited.
• V6 engines – The most popular of the V layouts in cars. They balance size, power and refinement, which is why you find them in many SUVs, premium sedans and sports cars. A V6 is also easier to fit in modern engine bays compared to an inline-six.
• V8 engines – Known for their power and iconic sound, V8s power everything from muscle cars to luxury sedans and full-size SUVs. They are performance-oriented but can be thirsty on fuel.
• V10 engines – Less common, but famous for being used in some supercars and performance sedans. They offer more power than a V8 but are not as smooth or balanced as a V12.
• V12 engines – A favourite for ultra-luxury cars and high-end sports cars. The V12 offers silky smoothness and huge power delivery. Brands like Ferrari, Lamborghini, Rolls-Royce and Aston Martin are well-known for their V12 models.
• V16 engines – Extremely rare and used mostly in ultra-exclusive cars or historical concepts. They represent the peak of excess in terms of power and engineering but are not practical for everyday cars.

The biggest advantage of V engines is that they can pack more cylinders into a compact block, which boosts performance without requiring extra space. They also deliver better balance in many configurations (especially V6 and V12). On the flip side, they are more complex to manufacture and service compared to simple inline engines.

Today, V6 and V8 engines remain the most common in cars, especially in SUVs and premium vehicles. The larger layouts like V10, V12 and V16 are reserved for performance and luxury, while smaller ones like V2, V3 and V4 have mostly faded away.

Here are the advantages and disadvantages of V-type engines:

Flat Engines

Flat engines, also called boxer engines, place cylinders in two horizontally opposed banks. This design lowers the centre of gravity, improves balance, and helps the car feel more planted on the road. The opposing pistons move in and out like two boxers throwing punches, which naturally cancels vibrations and makes the drive smoother.

Subaru is one of the biggest adopters of this layout, using it in models like the Impreza, Forester, and Outback, where handling and stability matter most. Porsche has taken boxer engines to legendary heights, powering cars such as the 911 Carrera, Cayman, and Boxster. Even BMW Motorrad uses flat-twin engines in motorcycles like the R 1250 GS, prized for their balance and reliability.

The trade-off is that boxer engines are more complex to design and maintain. Their wide shape also consumes more space under the bonnet, limiting their use in compact cars. Still, when tuned well, they deliver a mix of performance and driving pleasure that inline and V engines often struggle to match.

Flat engines are commonly used in sports cars and some high-performance vehicles.

Here are the advantages and disadvantages of flat engines:

Hybrid Engines

Hybrid engines are one of the smartest innovations in the car world today. They bring together the traditional internal combustion engine (ICE) and the modern electric motor, giving you the best of both worlds. This setup not only improves fuel efficiency but also lowers emissions, making hybrid cars a great choice for eco-conscious drivers who don’t want to give up convenience.

There are three main types of hybrid car engines you’ll come across:

1. Mild hybrids
Mild hybrid cars use a small electric motor to support the petrol or diesel engine. The motor kicks in during acceleration or when you’re slowing down, helping to save fuel. However, it cannot power the car on its own. This makes mild hybrids an affordable and simple entry point into hybrid technology.

2. Full hybrids
Full hybrids are more advanced. They can run on just the engine, just the electric motor, or a mix of both, depending on driving conditions. For example, in city traffic, the electric motor might handle short distances, while the petrol engine takes over on highways. This flexibility makes them highly fuel-efficient and great for mixed driving styles.

3. Plug-in hybrids (PHEVs)
Plug-in hybrid engines come with larger batteries that you can recharge using an external charger at home or at public charging stations. PHEVs let you drive longer distances on pure electric power before the engine kicks in, which is perfect for short daily commutes. When the battery runs low, the car simply switches to the petrol or diesel engine, so you don’t have to worry about range anxiety.

Here are the advantages and disadvantages of hybrid engines:

Common Engine Problems and Issues

Car engines are the heart of your vehicle, but like every complex machine, they can face several challenges over time. Spotting car engine problems early not only saves money but also prevents sudden breakdowns that could leave you stranded. Since most modern cars rely heavily on electronics, it’s often difficult to self-diagnose. That’s why it’s always wise to get engine issues checked at an authorised service centre, especially if your car is still under warranty.

Some of the most common engine issues drivers come across include overheating, oil leaks, misfires, poor performance, and that dreaded check engine light glowing on the dashboard.

Overheating usually happens when coolant levels drop or the radiator develops a fault. Misfiring, on the other hand, can be traced back to worn spark plugs, fuel supply issues, or poor compression inside the cylinders.

Oil leaks are another headache many car owners face. A worn gasket, damaged seals, or even a cracked engine block can lead to oil dripping out, which not only creates a mess but also reduces lubrication inside the motor.

Similarly, a sudden dip in fuel economy or sluggish acceleration may point towards a clogged air filter, faulty oxygen sensor, or malfunctioning injectors.

The check engine light is a tricky one; it could be something minor like a loose fuel cap, or it could signal more serious engine repair needs such as emission control problems or a failing catalytic converter.

Exhaust smoke is also a big giveaway of internal troubles. Blue smoke usually means oil is burning inside the engine, white smoke often points to coolant leaking into the cylinders (a possible head gasket failure), and black smoke means too much fuel is being burned due to injector issues.

Beyond these, there are some other car engine maintenance concerns worth noting. A rough idle or stalling can be caused by vacuum leaks or a dirty throttle body. 

Strange knocking or tapping noises may hint at worn bearings, low oil pressure, or poor-quality fuel. Timing belt or chain failure is another serious issue – if it breaks, the engine can suffer catastrophic damage.

Even a weak or failing battery can sometimes show up as an engine problem, as the car’s electronics and sensors depend on stable voltage to run smoothly.

To make things simpler, here’s a quick reference table that highlights the most common engine problems, their causes, and how urgently you should act.

The Bottom Line

The automotive industry is evolving faster than ever, with exciting advancements in engine technology shaping the way we drive. From hybrid cars that balance efficiency and power, to the rise of electric engines offering cleaner alternatives, buyers today have more choices than ever before. The focus is no longer just on speed, but also on fuel efficiency, lower emissions, and long-term reliability.

For anyone exploring the best engine cars in 2025, the future looks promising, with innovations in combustion technology, alternative fuels, and smart vehicle integration leading the charge. Whether you are looking for performance-focused petrol engines, economical diesel options, or modern hybrids for city and highway driving, engine technology is clearly moving towards smarter, greener, and more dependable solutions.