Stroke One

INTAKE

Color Index

Air

Fuel

Air-Fuel Mixture

Process Beakdown

1

Outside air is sucked in and stored in the intake manifold.

2

The fuel injector sprays fuel into the intake manifold, creating an air-fuel mixture.

3

The piston decends, sucking the air-fuel mixture into the cylinder once the intake valve opens.

INTAKE EXHAUST

Stroke Two

Compression

INTAKE EXHAUST

Color Index

Air-Fuel Mixture

Compressed Mixture

Process Beakdown

1

With the intake valve now closed, the piston ascends and compreseses the air-fuel mixture.

2

Compressing the air-fuel mixture increases its pressure, temperature, density, and overall flammability; making the explosion in the power stroke more powerful.

Stroke Three

Power

Color Index

Compressed Mixture

Spark

Explosion

Exhaust Gas

Process Beakdown

1

Once the piston returns to the top of its stroke and the air-fuel mixture is compressed, a spark is emitted from the spark plug.

2

The spark ignites the compressed air-fuel mixture, resulting in combustion, which drives the piston back down.

3

Following combustion, the spent air-fuel mixture (exhaust gas) remains in the cylinder.

INTAKE EXHAUST

Stroke Four

Exhaust

INTAKE EXHAUST

Color Index

Exhaust Gas

Process Beakdown

1

As the piston ascends, the exhaust valve opens, allowing the exhaust gas to escape from the cylinder.

Full Cycle

4-Stroke Cycle

INTAKE EXHAUST

© 2015 Project Horsepower