How Do Exhaust Brakes Work: What They Do and How They Work on an Engine

Converting energy into heat rather than mechanical energy is called thermodynamics. This means that every engine generates heat during its operation, and a turbocharger uses this heat to increase the engine's power output. An exhaust brake converts some of this heat into kinetic energy, slowing the vehicle down.

Exhaust brakes are designed to slow a vehicle faster than the brakes. Depending on the engine type, these brakes collect the engine's exhaust gasses and convert them into heat via a recirculation valve.

How do exhaust brakes work? For your vehicle to brake more efficiently, you need an exhaust brake. These brakes are a part of your vehicle's exhaust system, and they slow your car down quickly by converting heat.

They are most commonly found on large trucks with diesel engines that need to continue at slower speeds after making a delivery. Car exhausts are primarily for emission control (i.e., removing dangerous gasses like NOx), not braking.


Table of Contents

How do they work?

Exhaust brakes work using the engine's vacuum to capture exhaust gasses and convert them into heat. Exhaust gas recirculation (EGR) helps regulate the flow of gasses through the system, reducing the speed of your vehicle.

The brake normally works as follows:

When you drive off, there is not enough vacuum to run the system and generate a significant amount of heat.

When you accelerate, the vacuum in your car increases, but there is still not enough power to fully activate the brake.

As speed increases, an EGR valve releases all the air from the brake, increasing power and generating more heat in the exhaust system. At this point, you reach your desired speed and stop.

When you come to a stop, the vacuum in your car becomes even stronger, causing the EGR valve to close completely. Again, the engine produces less power and generates less heat.

How does a diesel exhaust brake work?

The exhaust brake slows the exhaust gasses out of the engine, reducing backpressure. This puts less force on the piston, which means less power is needed to move the engine's crankshaft. As a result, the engine runs at a lower RPM, allowing the driver to reduce speed without pressing the accelerator pedal.

A diesel engine consists of two main components: a combustion chamber and a turbine. The combustion chambers contain fuel and air, and the turbines have hot gasses that push against the blades of the compressor.

The compressor compresses the air, increasing its temperature and pressure. Ensuite, the compressed air is injected into the combustion chamber, mixing with the fuel and igniting. The resulting outbreak pushes the piston down and forces the exhaust valves to open.

How Do Exhaust Brakes Work

A diesel engine uses a turbocharger to increase the volume of air entering the combustion chamber. This results in the engine producing more torque or horsepower. The turbocharger cannot compensate for the increased load when running at full throttle, and this is why a diesel engine needs a turbocharger.

The second set of rotating cylinders compresses the intake air before entering the first set. This increases the volume and density of the air entering the combustion chambers and reduces the time needed for the fuel-air mixture to combust. A turbocharged diesel engine can produce up to 50 percent more horsepower than a naturally aspirated engine.

What makes exhaust brakes efficient?

The best way to explain this is to compare them to a normal brake. When you apply a normal brake, your vehicle slows down gradually. This means that if you want to stop your vehicle from moving forward, you must first apply enough pressure to slow it down. Once slowed down, release the brake and let gravity take over.

If you were to use an exhaust brake instead, you could stop your vehicle immediately. Instead of applying pressure to slow your vehicle, you would create a vacuum around your tires. This vacuum pulls the air out of the tire and makes it harder to stick to the ground. When you remove the vacuum, the tire begins to spin freely again.

This method of stopping your vehicle is much more effective because it requires no extra effort from you. You do not need to step on the brake pedal to slow down your vehicle; you need to remove the vacuum.

The advantages of exhaust brakes

The brakes are an indispensable safety feature of any vehicle. It is possible for you to hurt yourself if you collide head-on with something. The same goes for pedestrians, who may not see you coming. That's why they are so important. But what about the environment? What's the point of saving gas if you still have to drive somewhere?

Exhaust brakes are supposed to help reduce emissions. By reducing the friction between your tires and the road, you can significantly limit the pollution caused by vehicles. According to EPA, every 1% reduction in rolling resistance can lead to a 3.5% reduction in carbon dioxide emissions.

Exhaust brakes are also great for improving performance. A properly adjusted exhaust brake can reduce fuel consumption by 5%. That's right; you can get better fuel economy and go faster simultaneously!

Exhaust brakes create back pressure in the cylinders.

The exhaust brake slows down the engine and creates backpressure, and this causes the piston to move down into its cylinder bore and pushes the exhaust gasses out of the engine.

In the event of an exhaust valve opening, the piston moves downward and creates a vacuum in the cylinder. The vacuum removes the air from the tire, reducing traction and allowing the wheel to spin freely.

The exhaust brakes are the only way for drivers to stop their cars.

The best way to safely stop your vehicle is to apply the brakes. However, if you do not have adequate control over your vehicle, exhaust brakes may be your only option. Exhaust brakes are very powerful and can cause serious damage to your vehicle if not used properly.

If you are going to use an exhaust brake, you should know how to use it properly. Check out our guide below:

Exhaust brakes prevent normal brakes from overheating.

The heat generated by braking causes the friction material in your brake pads to melt, making them ineffective and requiring regular replacement. Heat is diverted from the brake pads to the exhaust system with an exhaust brake. This keeps the temperature of the brake pads from rising above a safe level, so they last longer.

Exhaust brakes can be controlled manually or automatically.

You can either activate the exhaust brakes manually or let the computer do it for you. Most modern cars are equipped with automatic systems that allow the driver to set different modes depending on the conditions. For example, you can switch the system to manual mode when the engine is cold and then switch it back to automatic once it has warmed up.

Exhaust brakes can prevent a vehicle from going downhill too fast.

In order to understand this, you should think of the system like a parachute. When you jump off a building, you want to slow down, so you do not hit the ground at 100 mph. An exhaust brake does just that, and it slows your vehicle down so you can stop safely without hitting the rear of your vehicle.

Exhaust brakes are not just for big trucks.

While most people associate exhaust brakes with heavy trucks, they can be installed on any vehicle. The same technology that allows us to go over 200 miles per hour in our sports cars can also help us stop safely.

Exhaust brakes are completely silent.

The noise produced by an exhaust brake is extremely quiet, making them ideal for city driving. They do not slow down your car's speed as much as traditional brakes, but they are still effective enough to stop your car safely.

Exhaust brakes can extend the life of normal brakes.

Brakes wear out over time, and otherwise, they can suddenly fail and cause an accident. Exhaust brakes gradually slow down your car, allowing you to stop safely before the brake pads normally wear out. They contribute to the long life of your brakes.

Exhaust brakes can be installed on all vehicles.

The best way to install them is to remove the catalytic converter from your vehicle, and this will allow you to install the exhaust brake directly into the exhaust pipe. If you do not want to go this way, install the exhaust brake with a stock muffler.

Extended life

The average life of a truck tire is about 60,000 miles, but if you take proper care of it, it can last twice as long. A well-maintained set of tires will give you better traction, handling, and fuel efficiency.

Constant braking power

The amount of energy required to decelerate a vehicle depends on its speed, and at higher speeds, less energy is needed. Similarly, vehicle braking systems must be adjusted, and consequently, the brake pedal must be adjusted accordingly.

Continuous braking

The exhaust brake slows down your truck by converting engine heat into thermal energy. When the exhaust temperature rises, friction occurs between the piston rings and the cylinder walls, causing the piston to slow down.

Exhaust brakes relieve the wheel brakes.

The advantage of an exhaust brake is that you can slow your truck down without applying the brakes. Consequently, you'll have fewer wear and tear on your brakes and less risk of them overheating.

How does an exhaust brake work on the Duramax?

The Duramax 6.6L V8 has two turbochargers and four exhaust valves per cylinder head. It uses a variable geometry turbine wheel to control the airflow into each turbocharger. This lets the engine lean at high loads but still delivers enough air for peak performance.

How does the duty cycle of an exhaust brake work?

The power stroke of an exhaust brake converts the energy of the hot gasses into kinetic energy that slows the car down. This process happens because the exhaust gasses are forced back into the cylinder, hitting the piston and pushing it down.

As the piston moves downward, the air in the cylinder is compressed, increasing its volume. This increase in volume creates more pressure, which pushes the exhaust gasses out of the cylinder.

As the exhaust gasses leave the cylinder, they release their energy in the form of heat. This heat causes the piston to cool, which lowers the pressure in the cylinder. A piston returns to its starting position when the pressure drops, stopping the cycle. 

How does an exhaust brake work on the 6.6 Duramax?

The 6.6L Duramax has a turbocharger that increases the air entering the engine, which means that the engine needs less fuel to produce the same power. If you want to know how this affects your truck's performance, read our article on how to optimize your Duramax 6.8L.

How does an engine exhaust brake work?

The main function of an exhaust brake is to slow down your truck or SUV quickly. Unlike other brakes, this type of brake converts exhausts energy into heat energy instead of stopping your vehicle. This means that it only works when the temperature of the exhaust gasses is high enough.

For example, if the temperature of the exhaust gasses coming out of your tailpipe is below 200 degrees Fahrenheit, you can not use the exhaust brake.

How does the exhaust brake system work in a car?

The exhaust brake slows down your vehicle by converting the energy of hot gasses into heat energy. As a result, kinetic energy in exhaust gasses is converted into heat energy, which then heats the exhaust pipe.

As a result, the temperature rises, causing the exhaust pipe to expand and the piston to return to its original position. This movement causes the engine to slow down. The exhaust brake also ensures that the engine runs smoothly.

How does the exhaust brake work in a truck?

The exhaust brake in a truck works similarly to the exhaust brake in a car. There are, however, a few differences:

  1. The exhaust brake in a truck is located near the rear bumper.
  2. The exhaust brake in a truck is connected to the exhaust manifold, not the exhaust pipe.
  3. The driver must manually operate the exhaust brake in the truck.
  4. The exhaust brake in passenger cars can be used when driving forward but not when reversing.
  5. The exhaust brake in cars can be activated either automatically or manually. 

How does the exhaust brake work on the Ford Super Duty?

Exhaust braking slows down your truck by converting hot exhaust gasses into thermal energy. This raises the temperature of the exhaust gasses, which then heat the surrounding air and convert it into thermal energy. This heat is then transferred to the exhaust pipes, causing them to expand and slow down the exhaust flow.

As the exhaust pipe is connected to the exhaust manifold, it expands outward, pulling the piston back toward the top of the cylinder. This movement slows the engine and allows the driver to apply the brakes without worrying about stalling.

How do exhaust brakes and wheel-mounted brakes work?

The brakes are activated by a sensor located in the exhaust pipe. The brakes begin to work once the sensor detects that the temperature has risen above a certain point.

The sensors are usually located near the back end of the exhaust pipe, where they detect the exhaust pipe's hot gasses. This causes them to activate the brakes. The brakes slow down the engine as the exhaust pipe expands and pulls the piston back into the lower part of the cylinder.

How does the working cycle of an exhaust brake work?

The power stroke of an exhaust brake is similar to that of a conventional piston. The only difference is that hot gasses, rather than air, are forced out of the engine. This slows down the engine so that the driver can stop safely.

Reasons why the exhaust brake is not bad for the engine

The main benefit of an exhaust brake is that it reduces back pressure in the engine, allowing the engine to rev higher and burn fuel more efficiently. It also prevents the formation of carbon monoxide and unburned hydrocarbons.

Frequently Asked Questions (FAQs)

1. How does the Ford exhaust brake work?

The Ford exhaust brake uses a series of pipes that run from the back of the engine to the front of the vehicle. As the exhaust gasses expand, they push against the pipes, forcing them to move down into the engine block. This stops the upward movement of the piston, slowing the engine.

2. How does the Mercedes exhaust brake work?

The Mercedes exhaust brake works similarly to the Ford exhaust brake system. However, instead of pushing against the cylinders, the Mercedes exhaust brake pushes down on the exhaust manifold, which bends the piston rod, slowing down the engine.

3. Is the exhaust brake bad for the engine?

Yes, they can harm your engine. The exhaust brake heats the exhaust gasses, causing them to expand. This expansion causes the piston rings to stick together and stop working properly. The engine no longer runs smoothly and can eventually fail when this happens.

4. Why should you use an exhaust brake?

The main benefit of an exhaust brake is that you can slow down your truck without applying the brakes. As a result, it is easier on the tires and suspension components. It's also safer because you do not have to worry about losing control of your vehicle if you hit something hard or hit the brakes too soon.

5. Are exhaust brakes hard on the engine?

Yes, they are. Not only do exhaust brakes have to convert the vehicle's kinetic energy into heat, but they also have to work harder than normal, and the engine has to work harder to move the vehicle forward.

6. Is it a smart idea to use the exhaust brake while driving?

Yes. It is important to know that this is a safety feature and helps reduce emissions. If you do not drive with the exhaust brake on, your vehicle will emit more pollutants into the air than if you do.

7. Should I always use my exhaust brake?

Yes, if you want better gas mileage. It is best to use your exhaust brake only when going downhill. This allows the brake to convert heat energy into kinetic energy, slowing your car down without fuel. If you do not use your exhaust brake, your car will use more fuel to slow down.

8. When should I use a diesel exhaust brake?

If you want to slow down quickly, you should use an exhaust brake. The best way to find out if this will work for you is to test it yourself, and it is important to know that not all vehicles are equipped with it.

9. Is it bad to use an exhaust brake?

The exhaust brake is usually used for emergency braking, but it is not recommended for everyday use, and it can cause damage to the engine if used improperly.

10. Are exhaust brakes harmful to engines?

Yes, they can be pretty hard on the engine. But when you look at the big picture, they save fuel and reduce emissions. Read this article from our sister site, Top Gear, if you want to know more.

11. When should you use exhaust brakes?

The best time to use them is when braking from high speeds, and they slow your vehicle down without damaging the engine. Therefore, if you do not already own an exhaust brake, you should consider purchasing one. It's not always necessary, but it's worth considering if you drive a heavy truck or SUV.

12. Will an exhaust brake harm the engine?

No, they do not. The exhaust brake helps the engine run cooler and smoother. It is not harmful to your engine, but it does require some maintenance.

13. Should you always use an exhaust brake?

Yes, you should always use an exhaust brake. It is best used during heavy braking when you quickly slow down. If you do not use an exhaust brake, your vehicle will continue to accelerate instead of slowing down. As a result, you may damage your car if you are traveling too fast.

14. What is the purpose of an exhaust brake?

The main benefit of an exhaust brake is that you can slow down your truck or SUV without applying the brakes. It means fewer problems with tires and suspension components and less fuel consumption. It's important to know that not all vehicles are equipped with exhaust brakes. If this is not the case with your vehicle, do not worry!

15. Is it bad to leave the exhaust brake on Duramax?

The exhaust brake should only be used during cold starts, and then only briefly. If left on too long, it will cause damage to the catalytic converter. It's best to let the exhaust brake cool off before removing it.

Conclusion

Exhaust brakes are a great innovation for your diesel engine. They are installed on the back of the engine near the exhaust manifold. In a diesel engine, the exhaust from the engine is mixed with the air and pumped into the intake manifold.

The exhaust manifold then sends it straight back into the exhaust without mixing in the air. This results in a cleaner running engine and less fuel used. They also help with noise reduction, emission control, and cylinder deactivation.

However, there are some disadvantages to exhaust brakes. They can make your engine run hotter than expected, they clog easier than normal, they decrease fuel efficiency, and they are more expensive to install as they require a new exhaust system.

John
 

John D. Archer is a mechanical engineer and writer based on the area of automotive accessories at brakeshub.com, A resident expert and professional, John is passionate about all things automotive and loves to share his knowledge. He has good experience in all kind of automotive accessories. He has worked as a chief mechanical engineer in some reputed automotive garage firm.