What Is An Inline Engine: Types, Applications and Components

An inline engine, also known as a straight engine, is a type of internal combustion engine where the cylinders are arranged in a straight line along the crankshaft. Depending on the design, the cylinders can be oriented vertically, horizontally, or at some angle in between.

The number of cylinders also varies, such as 2, 3, 4, 5, 6, or 8.

The engine has a straightforward design and is commonly used in vehicles like cars, trucks, and motorcycles.

Inline engines are classified based on the number of cylinders and their arrangement. The common types include:

Inline-2 engine: It features two cylinders arranged in a straight line.

Inline-3 engine: There are three cylinders.

Inline-4 engine: There are four cylinders. Their use is common in cars, motorcycles, and light trucks.

Inline-6 engine: There are six cylinders. The engine is known for its strong torque characteristics.

Inline-8 engine: With eight cylinders, it has a simple design and is relatively more affordable.

An in-line engine follows a four-stroke cycle: intake, compression, power, and exhaust.

Intake Stroke: The piston moves down, letting an air and fuel mixture enter the cylinder.

Compression Stroke: The piston moves up, compressing the air-fuel mixture to prepare it for combustion.

Power Stroke: The compressed mixture is ignited by a spark plug, causing an explosion that forces the piston down and generates power.

Exhaust Stroke: The piston moves back up, pushing out the burned gases through the exhaust valve.

This cycle repeats continuously, with each cylinder firing sequentially and powering the engine to move the vehicle.

Inline engines have widespread applications. They are fitted in various vehicles, from the compact ones to the heavy-duty trucks. Their efficiency and adaptability make them a perfect choice for different automobiles.

Compact and midsize cars: The inline 4-cylinder engine is the standard choice for compact and midsize cars. Its power, efficiency, and affordability fulfil the needs of everyday commuters.

Light trucks and SUVs: The four and six-cylinder inline engines are commonly used in light trucks and SUVs. Due to their versatility, manufacturers can use them for towing power in trucks and fuel efficiency in SUVs.

Commercial and industrial vehicles: Inline engines are also suitable for industrial and commercial vehicles. Due to their robust design and adaptability, they are fitted in delivery trucks, powering buses, and also some heavy machinery.

Sports cars: The in-line six engine has proved its power even in the sports car segment. Its smooth operation and balance of power are attractive features for those desiring an engaging driving experience.

The various components present in an inline type or straight engine include:

Housing: The components of an inline engine are enclosed within an external covering known as the housing.

Piston: The piston exists inside the combustion chamber and is responsible for generating power from the fuel mixtures.

Cylinders: The cylinders contain fuel to generate power and move the vehicle forward.

Connecting rods: These rods join the pistons to the crankshaft.

Camshaft: This component transforms the piston’s rotatory motion back into the reciprocating motion.

Crankshaft: This component converts the piston’s reciprocating motion to rotatory motion. As a result, the flywheel rotates to help the wheel move forward.

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What are the benefits of an inline 4-cylinder engine?

An inline engine is relatively lightweight because of its compact design. Its manufacturing cost is lower, and it is also easier and safer to work with.

What are the differences - inline vs V engine?

In an in-line engine, the cylinders are arranged in a single row. On the other hand, the cylinders of a V-shaped engine are positioned in two banks at a 60 or 90-degree angle.