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Engine Braking Explained in the Simplest way possible

Engine Braking Explained in the Simplest way possible

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  • Post last modified:February 14, 2023
  • Post category:Cars
  • Post comments:5 Comments
  • Reading time:9 mins read
Subaru boxer engine being used to demonstrate engine braking

Vehicles have come a long way since their inception in the 19th century. Almost every aspect of the car has either been improved or replaced with the aim to improve on efficiency, safety, maintenance as well as the duration of the vehicle. Carburetors came and left. Advanced safety features such as traction control, stability control, ABS and torque vectoring were added and improved over time. Heck, even steering became electronically controlled. But there is one important part that has had little to no changes over this period of time, and that’s brakes. Even with the gradual extinction of internal combustion engines, hydraulic brakes have still found a way to penetrate the EV market. I guess if it ain’t broke, don’t fix it.

There have only ever been two types of brakes since the early days; drum brakes and disk brakes. However, there is another smart way of braking, which is rarely talked about; engine braking. Engine braking simply refers to releasing the accelerator pedal and down shifting to gradually slow down the vehicle. This method is mostly common in manual cars, but automatic vehicles are just as capable. In this article, we are going to look at how engine braking works, its benefits and I will finally give you my final thoughts.

What is Engine Braking.

Mercedes Benz Brake calipers

As explained earlier, engine braking simply refers to releasing the accelerator pedal and downshifting to gradually slow down the vehicle. This method works for both automatic and manual vehicles although it works better in the latter. This is mainly due to the ability to manually shift between gears. Let’s get a bit technical on how this process works, shall we?

When you apply pressure on the accelerator pedal, you increase the amount of air going to the cylinders. The more the air, the higher the rate of combustion which leads to faster acceleration. But what if you suddenly let go of the accelerator pedal when the car is traveling at a higher speed? Well, in this case, the car is running on less air than needed which leads to a low rate of combustion. The car in turn starts to decelerate.

Here is a more detailed way of looking at it. When you let go of the accelerator pedal, a partial manifold vacuum is created in the cylinder since there is no air to fill the void. This makes it harder for the engine to produce power causing a deceleration. In addition to this, the pistons have to work against the vacuum created leading to a gradual slow down of the vehicle.

If you drive a manual, as the engine Revs decrease, it is common sense to downshift which again slows down the vehicle. If you have an automatic car with either paddle shifts or a manual mode, you can as well downshift to gradually slow down the vehicle.

As stated earlier, the high manifold vacuum contributes a large percentage to engine braking as the pistons have to work against it. In addition to this, the friction in the drive train also contributes some percentage in engine braking.

Is Engine Braking bad?

Car braking system

Some people claim how bad this type of braking is on your engine. They couldn’t be more wrong. See, the engine is a very strong unit meant to withstand high temperatures as well as stress over a sustained period of time. As a matter of fact engine braking could be much beneficial than people give it credit.

First and foremost, engine braking reduces wear and tear on your brakes. It is always important to periodically check the state of your brakes. It goes without saying that you need to change our break pads when they wear out to minimize brake fading. When you get used to engine braking, you actually save on the frequency of changing your brake pads due to reduced wear and tear. Another bonus accompanying engine braking, is that you save on the cost which would have otherwise been used to replace your brake pads every now and then.

The second advantage to engine braking, is improved fuel efficiency. When you let go of the accelerator pedal, the electronic control unit (ECU) shuts off the supply of fuel to the fuel injectors. This ends up saving on fuel costs hence improving on efficiency.

The third advantage to engine braking is that it is safer down hill. When going down a hill, the weight of the car plus the gravity of the earth on the vehicle increase the amount of force needed to slow down the vehicle. Constantly using the brakes more so when not needed imposes a strain on the brakes which can lead to brake fading over time. A good solution to this is engine braking. Just maintain low gears and let go of the accelerator pedal. With all this in mind, use the brakes when the need arises.

Benefits of engine braking.

  • It’s better for the engine.
  • Safer downhill.
  • Reduces wear and tear on the brakes.
  • Improves fuel efficiency.
  • Leads to lower maintenance on the brakes.
  • Cost effective both on fuel and brake pads.

FAQs on Engine braking.

  • Does engine braking cause damage to the engine and other car parts? No. As a matter of fact, it leads to fuel efficiency as well as low brake maintenance in the long run.
  • How does engine braking work in a more simplified way? When you are cruising at a high speed, letting go of the accelerator pedal limits the amount of air entering the engine cylinders leading to a gradual slow down.
  • Does engine braking work on an automatic car? Of course it does.
  • Does engine braking damage the transmission? No, as long as you downshift at the right moment.
  • Do trucks and heavy vehicles use engine braking? Yes they do, but they use a more complex system called the Jake brake.
  • Can engine braking be used in place of the hydraulic brakes? Of course not. Engine braking is only meant to supplement hydraulic brakes. In case of an emergency, the hydraulic brakes should always be used. Remember, safety first.
  • Which are the main ways in which engine braking is achieved? There are basically two ways in which this system brings the car to a gradual stop. The resistance caused by the manifold vacuum and the friction in the drive train.

Final thoughts.

An alternator

Engine braking is a cool concept and most of us do it every day without even realizing it. Now that you know how it works and its benefits, maximizing it on your daily commute will have you car thanking you in the long run. Fuel efficiency as well as a smooth ride are also guaranteed. But for the sake of your own safety, kindly use the foot/ hydraulic brakes when need be. If you found this article informative or useful, be sure to share it with others.

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