Turbocharger Impellers

Many types of engines depend on turbochargers to boost engine power and maintain fuel efficiency. In addition to the turbine, shaft, and compressor, one of the essential components in a turbocharger system is the impeller, which draws in and compresses the air that enters the engine.

At Ferralloy, we are a leading supplier of high-quality vacuum investment castings that meet the needs of various applications, including vacuum investment cast turbocharger impellers. Learn more about this critical component, the materials used to manufacture turbocharger impellers, and their effect on engine performance.

Turbocharger Impellers: Basic Design and Function

In a turbocharger system, the volume of the engine’s exhaust directly affects how much power it generates. A turbocharger has two sides: a “hot,” or exhaust, side that contains a turbine, and a “cold” side that compresses clean, external air. The impeller sits on the cold side.

Also known as a compressor wheel or turbine wheel, the impeller is a critical part of a turbocharger system. This fan-like component has a flat, circular base with tapered, angled radial blades. The shape and distribution of the blades, along with the speed at which the impeller spins, control how much the air is pressurized and the amount of oxygen that enters the combustion chamber.

The turbine and impeller are connected by a shaft that spans the length of the turbocharger. Engine exhaust causes the turbine to spin, which in turn causes the shaft and impeller to spin. The impeller pulls in fresh air, compresses it, and delivers it to the engine. As the impeller’s speed increases, so does the air pressure. The high oxygen level of the compressed air allows the engine to burn more fuel and generate more power and torque.

Common Materials for Turbocharger Impellers

Turbocharger impellers are exposed to high temperatures and pressures for prolonged periods in vehicle and aircraft engines. Materials used to manufacture them must be able to resist temperature and pressure extremes as well as centrifugal and other forces applied during operation. The best material options can hold the intricate shape and configuration of the impeller blades without damage in a specific application. Common options include:

• Titanium and stainless steel: These are popular turbocharger impeller materials due to their ability to withstand high pressures and temperatures.
• AISI 4063 Steel, Inconel 718, Titanium 2646: These materials offer a range of beneficial properties that make them suitable for turbocharger impellers. Specifically, they are chosen due to their ability to hold up against high pressures, temperatures, and centrifugal loads.

Engine Efficiency and Power

Turbocharger impellers impact engine efficiency and power output in these key ways:

• Increased torque and power: The impeller in a turbocharger increases oxygen supply to the engine, which allows the engine to burn more fuel and generate higher levels of torque and power.
• Optimized combustion efficiency: The impeller enables the engine to burn more fuel and generate more power. As a result, turbochargers can make it possible to generate the same amount of power with a smaller engine.
• Reuse of exhaust energy: The impeller is driven by an exhaust-powered turbine and shaft. In effect, the engine’s waste products (i.e., exhaust) are reclaimed in order to pull more oxygen into the engine and boost power more efficiently.

Turbocharger Impellers From Ferralloy, Inc.

Ferralloy specializes in heat-resistant alloy castings and fabrications for high-temperature applications – such as turbocharger impellers. We also offer capabilities and products including closed die and rolled ring forgings, machined bar stock components, investment castings, and a range of raw material superalloys and refractory alloys. Our products are used in the thermal processing, heavy equipment, automotive, and aerospace industries, among others.

For more information about our products and services, or to discuss your next project, please contact us today.