Turbochargers have been a marvel of mechanical engineering. They are almost an essential part of any vehicle that’s running on a diesel engine. But why is that and how does a turbo work on a diesel?
Read on as we discuss the many components of the turbo and how they work to benefit a diesel engine.
What Is a Turbo?
A turbocharger, or turbo for short, is a device used on diesel engines. It helps boost performance while being energy and environmentally efficient. The turbo components compress excess air back into the engine, creating more power.
Since the invention of turbochargers in 1905, they have gained widespread popularity.
Cars, vans, and heavy-duty trucks with diesel engines are common vehicles with turbo. This is due to the benefit of the power output, efficiency, and emissions control.
We offer various turbochargers for sale from manufacturers like Mitsubishi, Garett, GMC, and more for different vehicles and industries.
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How Does a Turbo Work on a Diesel?
A turbo captures the engine’s waste exhaust gasses in the turbine. These gasses are then compressed in the compressor and fed back into the engine. This new cold compressed air enables the engine to produce more power by making the fuel burn more efficiently.
Turbochargers can boost an engine’s horsepower and thermal efficiency. A non-turbocharged engine cannot produce as much energy from the same amount of fuel as a turbocharged engine.
This makes turbocharged engines more potent and less expensive to run. All this is possible while meeting EPA standards.
A Step-By-Step Guide on Turbocharging
Let's take a closer look at the question, how does a turbo work on a diesel engine? The turbo has two main components, the turbine and the compressor. The process of producing more power takes place during four segments:
- Capturing exhaust gasses.
- Wheel spin.
- Venting exhaust gasses.
- Compressing air.
1. Capturing exhaust gasses
The engine produces hot gasses during combustion. These gasses escape through the exhaust pipe in a regular vehicle. But on a turbocharged engine, the turbo captures these gasses.
2. Wheel spin
The excess engine gasses cause the turbine wheel blades to spin. The spin can reach incredible RMP numbers depending on the size of the engine, turbo, and vehicle. The average car turbo can spin up to 150,000 RPM. This amount of spin reduced turbo lag.
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3. Venting exhaust gasses
The exhaust releases these gasses once they have made the turbine wheel spin.
The gasses first have to pass through the catalytic converter. This is a device inside the downpipe. The tailpipe releases these gasses once they're cleaned off their pollutant substances.
4. Compressing air
The turbine wheel powers the air compressor as it spins at high RPM.
The compressor sucks in clean and cold air from an intake vent. Then the compressor condenses it to 30% above atmospheric pressure.
The created dense oxygen-rich air goes into the combustion chamber, which helps the engine burn fuel more efficiently. This provides better performance than same-size engines that are not turbocharged.
Turbocharger Components
We must examine its components to understand further how a turbo works on diesel. How do these components interact with each other to produce more power for a diesel engine?
A turbocharger provides an engine with extra intake air pressure. It does this by combining a compressor wheel and a turbine wheel through a solid shaft. Exhaust gasses power the turbine, which then powers the compressor wheel.
Most automotive-related turbochargers use radial flow compressors and turbine wheels. Axial flow turbine wheels are rarer as they’re only suitable for low-speed diesel engines.
Center housing
A bearing system supports the center housing. The center housing holds the shaft that connects the turbine and compressor. This is also known as the shaft wheel assembly or the rotating assembly.
The central housing rotating assembly (CHRA) refers to the wheel shaft assembly. It’s usually made out of gray cast iron or aluminum.
Seals aid in preventing oil from entering the compressor and turbine. Some turbochargers have cooling passages in the CHRA. They’re used for high exhaust gas temperatures like internal combustion engines.
Bearing system
The bearing system of a turbo controls the radial and axial movement of the shaft and wheels. Another key function the bearing system performs is the minimization of friction losses.
Bearing systems are very popular due to the engine fuel efficiency and their impact on turbocharger friction.
The bearings in a turbocharger are usually placed in an overhung position. The most common position is between the turbine and compressor wheels.
The turbo will run over its first and second critical speeds thanks to the flexible rotor design. This makes it susceptible to rotor dynamic situations, including whirl and synchronous vibration.
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Seals
Both ends of the bearing housing have seals. Due to the requirement for minimal frictional losses, the relatively substantial shaft motions resulting from bearing clearance, and unfavorable pressure gradients in some circumstances. These seals pose a challenging design problem.
The purpose of the seals is to prevent intake air and exhaust gas from entering the central housing. The pressures in the engine crankcase and the intake and exhaust systems are often higher than in the center housing of the turbo.
Seals close up the center housing when the pressure is lower than the pressure in the intake and exhaust. These seals aren't the main way to keep oil from leaking into the exhaust and air systems. Methods like spinning flingers and oil deflectors help prevent oil from reaching the seals.
The typical turbocharger seal is usually a piston ring-type seal. These seals are different from the average rotating equipment soft lip seals. Soft lip seals are usually used at lower speeds and temperatures.
The turbo seal is a metal ring and remains stationary during shaft rotation. The turbo shaft seals will not stop oil leaking if the pressure differential flips. This is when the pressure in the center housing exceeds the intake or exhaust system.
Benefits of Turbochargers in Diesel Engines
There are various benefits to turbos that makes them so popular with diesel engines.
Enhanced performance
Turbo diesel engines have a higher power output compared to same-size engines with no turbo.
Fuel efficiency
Diesel engines are more fuel efficient than petrol ones by themselves. A turbocharger increases this efficiency factor even further.
Improved torque output
The increased air density and pressure in the cylinder inject more fuel. This results in more torque and power. Even the low-speed torque is higher.
More towing capacity
Diesel engines are able to pull more weight than petrol engines, and a turbo amplifies this. Turbocharged engines help farm machinery haul high loads and do off-road travel.
Environmentally friendly
Smaller engines produce lower green gas emissions. Manufacturers can create smaller-sized engines with great power and performance. This is due to the efficiency that turbochargers provide. They're doing this while reducing the environmental footprint of the vehicle.
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FAQs
Can a diesel car run without a turbo?
Yes, it can. But a turbocharged diesel engine outperforms a same-sized engine with no turbo.
How long does a turbo last on a diesel?
A stock turbocharger will last throughout the vehicle’s lifespan. An aftermarket one can last around 150,000 miles. But this all depends on the make and model of it, your driving habits, and maintenance. You can spot if a turbo has gone bad by the sound it makes and its decreasing performance output.
Can you repair a turbo?
Yes. It's possible to repair turbochargers and bring them back to their prime status. That’s why we offer both new, used, and refurbished turbochargers for different engine sizes and uses.
Conclusion
So, how does a turbo work on a diesel? It redirects excess exhaust gasses into its turbine and compressor. The compressed air then feeds the cooled air and feeds it back into the engine. This condensed air pressure helps the diesel engine burn fuel more efficiently, increasing the performance and economy of the vehicle
