What Is Engine Braking? — Is Engine Braking Good Or Bad For Your Car?

In petrol or diesel engines, air is sucked into the engine via the intake manifold. The throttle valve opens by pressing the accelerator pedal. Airnow enters the cylinder during the intake stroke when the intake valve opens. Air is required to initiate combustion in the engine.

When you are driving your car and suddenly takes your foot off the accelerator pedal, the throttle valve closes suddenly. The engine will still be trying to suck in air. But since the throttle valve is closed, only a small amount of air reaches the engine. This causes a vacuum to form in the intake manifold. Due to the vacuum, the engine suddenly loses power due to inefficient combustion and the car slows down. Do note that this is for manual transmission cars only.

Is Engine Braking Good Or Bad For The Car?

Contrary to popular belief, engine braking is actually good for your car. Engine braking also gives a better driving experience since it requires some practice to be executed well. Here are the main benefits of engine braking:

• Engine braking, in most situations, avoids the need for applying the brakes. This, in turn, increases the life of the brake pads.
• While going downhill, engine braking helps in making a gradual descent. Constant usage of brakes on a descent will heat up the discs/drums and brake pads. This will cause brake fading.
• Engine braking, unlike regular braking, is accompanied by reduced fuel usage. The reason being the closed throttle.
• Since engine braking is initiated just by taking your foot off the accelerator, the car can be controlled by just one foot. This reduces driver fatigue to a good extent.

Precautions To Be Taken While Engine Braking



Photo Credits: Transport Executive

• Though engine braking slows down the car, it doesn't illuminate the brake light. This means that cars behind you won't know that you are slowing down.
• If you are running on a low gear (engine rpm is noticeably high) and then initiate engine braking, the result won't be that good. The process will cause wear on your clutch and transmission. This is mainly because the transmission has to match the flywheel speed (engine speed) with the wheel speed. This process is also known as clutch braking, and is bad for your car. Often, engine braking is confused with clutch braking.
• Engine braking gradually slows down the car but doesn't stop it. In an emergency situation, forget about engine braking and its advantages. Just press the brake pedals.

Engine Braking In Automatic Transmissions



In automatic transmissions, there is no engine braking as such. Certain automatics allow you to downshift at high speeds. Depending on the car, it will cause wear on the transmission parts. In high-end cars, this wear is prevented by rev-matching. Rev-matching is the process of matching the engine speed with the wheel speed. This avoids chances of clutch wear and wheel lock-up.

Engine Braking In Certain Diesel Engines



Certain diesel engines (mainly trucks) employ engine braking as a separate system. Also called Jacobs Brake or Jake Brake, the mechanism opens the exhaust valves of the engine right after the compression cycle. This releases the compressed air and slows down the engine.

In diesel engines, combustion is initiated by spraying fuel (using a diesel fuel injector) into compressed air present inside the cylinder. When Jake Brake is applied, most of this compressed air is lost and combustion would be weak. This is how the engine loses power and slows down.

Thoughts On Whether Engine Braking Is Good Or Bad For Your Car



Engine braking is one among the hacks and tricks in driving. Execute it well and you end up with better brake pads and fuel economy. Execute it wrong, and get ready to face increased clutch wear. In the worst case, another car might hit yours straight from behind as you didn't illuminate the brake lights while slowing down. But coming to whether engine braking is good or bad, the answer is simple, Engine braking is good for your car!