The Importance of an Active Grille Shutter for Engine Efficiency

Understanding Active Grille Shutters: A Key to Modern Vehicle Efficiency

Active grille shutters (AGS) are a relatively recent innovation. They’re designed to improve a vehicle’s aerodynamics, fuel efficiency, and engine performance. As fuel efficiency and emissions standards become increasingly stringent, car manufacturers are continuously seeking ways to enhance the performance of their vehicles. Active grille shutters play a significant role in achieving these goals. This article explores what active grille shutters are, how they work, and their benefits.

What is an Active Grille Shutter?

Active grille shutters are adjustable slats located directly behind the front grille of a vehicle. Unlike traditional fixed grilles, these shutters can open and close based on the vehicle’s needs. Controlled by the vehicle’s computer system, they automatically adjust their position to optimize airflow and engine cooling.

Why carmakers use an active grille shutter?

The active grille shutter assembly accomplishes three things:

1) Aerodynamic efficiency— An active grille shutter improves aerodynamic efficiency at higher speeds. When it closes, it blocks airflow through the grille and radiator and forces the air to flow up and across the hood. Without the shutter, air would normally ram into the engine compartment. Since air can’t easily escape due to the engine bottom covers and the firewall, it instead forms a field of air in front of the vehicle that disturbs aerodynamic airflow.

• Closing the shutters at stable speeds reduces the drag coefficient, enhancing aerodynamic performance. This leads to optimized fuel consumption and reduced CO₂ emissions, potentially lowering them by up to 2g per kilometer.

2) Thermal Management— The shutter is closed on cold startup to prevent cold air from reducing the temperature of the coolant in the radiator and by stopping the flow of cold air around the engine, so it warms up faster. When the air conditioning is at its highest setting, the shutters open to allow maximum airflow to the radiator. This helps improve the aerodynamic drag coefficient by an average of 9%.

3) Improves cabin heating— Stopping the flow of cold air across the radiator keeps the coolant at a higher temperature so it can heat the cabin more efficiently. Why is this needed now? Because late model engines are much smaller and hold less coolant. Cold airflow across the radiator could chill the coolant to the point where cabin heat would be lukewarm.

When the active grille shutter operates

The ECU controls the active grille shutter operation.

The ECU opens the grille shutter at low speeds or when the engine temperature rises and needs requires additional cooling. That allows enough airflow to chill the coolant enough to remove engine heat.

The ECU closes the grille shutter as the vehicle’s speed increases to reduce drag and increase aerodynamic airflow across the hood.

Although the closed shutter reduces the amount of air going through the radiator, the increased airflow efficiency across the hood and the associated increase in MPG are more important. The radiator fan can pull heat out of the radiator if the engine needs moderate cooling.

The ECU commands a partial opening to regulate airflow through the radiator to keep engine temperature at the right level.

The shutters remain closed at engine startup and in cold weather.

The Active Grille Shutter Also Reduces Noise

Exterior noise is reduced by approximately 1.2 dB (decibels) when the shutters are closed, contributing to a quieter driving experience.

©, 2019 Rick Muscoplat