What Does the Inline-4 Turbo Engine Mean?

What Is an Inline-4 Engine?

An inline-4 engine, often called an i4 or L4, is a four-cylinder engine with all cylinders aligned in a straight line along one crankshaft. This compact and lightweight design makes it one of the most common engine types in modern passenger vehicles. Like other engines, the i4 operates on a four-stroke cycle to convert fuel into mechanical energy. The four-stroke cycle includes:

Intake stroke: Air and fuel mix enter the cylinder.

Compression stroke: The mix is compressed for ignition.

Power stroke: Combustion occurs, generating energy to power the vehicle.

Exhaust stroke: Waste gases exit the cylinder.

This cycle ensures smooth operation in i4 engines, whether naturally aspirated or turbocharged.

What Makes the Turbocharged Inline-4 Engine Special?

A turbocharged inline-4 engine adds forced induction to the mix. A turbocharger uses exhaust heat to power a turbine that forces more air into the engine’s combustion chamber. This additional air allows more fuel to burn, resulting in greater power output. With a turbocharger, an i4 engine can deliver performance comparable to a V6 while maintaining a smaller engine's fuel efficiency and environmental benefits. It’s a win-win for drivers who want power without compromising the economy.