Since the advent of the internal combustion engine, enthusiasts and engineers have sought ways to enhance power. Enlarging the engine is one approach, but it often leads to increased weight and higher costs without guaranteed improvements.
To enhance a standard-sized engine’s efficiency, introducing more air into the combustion chamber increases fuel, leading to a more powerful explosion and greater horsepower. Superchargers, which pressurize the air intake, provide a reliable method for forced air induction. While turbochargers are powered by exhaust gases driving a turbine, superchargers operate mechanically through a belt or chain drive connected to the engine’s crankshaft.
What is a Supercharger?
A standard four-stroke engine allocates one stroke to air intake, involving the piston moving down, creating a vacuum, and drawing atmospheric pressure air into the combustion chamber. This air combines with fuel to form a charge, ignited by the spark plug, leading to combustion and driving the piston down to transfer motion to the wheels.
Increasing fuel in the charge for a more powerful explosion is limited by the need for a precise air-fuel ratio. Superchargers, unlike turbochargers, directly draw power from the crankshaft, compressing air above atmospheric pressure without creating a vacuum. This boosts engine power by allowing more air and fuel into the charge. Superchargers add about 46% more horsepower and 31% more torque on average.
Superchargers, powered by an accessory belt, spin at 50,000 to 65,000 RPM, delivering a 6 to 9 psi boost. To enhance efficiency, intercoolers, available in air-to-air and air-to-water designs, cool the compressed air, increasing its density for a more potent combustion chamber charge.
Types of Superchargers
1. Roots Superchargers
Three main types of superchargers exist: Roots, twin-screw, and centrifugal, differing in how they move air to the engine’s intake manifold. The Roots supercharger, often seen atop drag cars, uses meshed rotors to compress incoming air. Twin-screw superchargers, featuring two interlocked rotors, compress air as they rotate. Centrifugal superchargers resemble snail shells, using an impeller wheel to compress air. While all boost performance, their efficiency varies. Available in different sizes, each type suits various preferences, from casual boosting to racing.
The Roots supercharger, the oldest design, was patented in 1860 for mine shaft ventilation. It became part of a car engine in 1900. Operating like air blowers, Roots superchargers are larger, sitting atop engines and protruding from hoods. Popular in muscle cars, they are less efficient due to added weight and discrete air bursts rather than a smooth flow.
2. Twin-screw Superchargers
A twin-screw supercharger operates by pulling air through meshing rotors that twist alongside each other, trapping air in pockets created by the rotor lobes. Unlike the Roots supercharger, the twin-screw compresses air inside the rotor housing due to conical tapering of the rotors. This design makes twin-screw superchargers more efficient, but their precision-manufactured screw-type rotors make them costlier.
Some types of twin-screw superchargers, like the Roots, sit above the engine and produce considerable noise. Noise suppression techniques are employed to subdue the whine or whistle from the compressed air exiting the discharge outlet.
3. Centrifugal Superchargers
A centrifugal supercharger powers an impeller, similar to a rotor, at speeds of 50,000 to 60,000 RPM, swiftly drawing air into a compact compressor housing. Centrifugal force causes the air to radiate outward, leaving the impeller at high speed but low pressure. Surrounding stationary vanes, called a diffuser, convert this air to low-speed, high-pressure by reducing velocity through collisions. Centrifugal superchargers, the most efficient and common forced induction systems, are compact, lightweight, and front-mounted.
They emit a distinctive whine during engine acceleration. Notable 2021 models with OEM centrifugal superchargers include the Jaguar XF, Dodge Charger, Volvo S90, and Ford Mustang. These superchargers can be added as after-market enhancements, with kits available for DIY installation. Customization with superchargers is prevalent in funny cars and fuel racers, and several auto manufacturers include them in production models.
Advantages of Superchargers
- Increased Horsepower: The primary advantage of adding a supercharger is a significant boost in horsepower, effectively transforming an ordinary vehicle into one with the performance characteristics of a larger and more powerful engine.
- No Lag: Superchargers, unlike turbochargers, don’t experience lag—the delay between pressing the gas pedal and the engine’s response. Directly driven by the crankshaft, superchargers deliver immediate and consistent power.
- Efficiency at Different RPMs: Superchargers exhibit varying efficiency across RPM ranges. Roots and twin-screw types excel at lower RPM, delivering more power, whereas centrifugal superchargers are more efficient at higher RPM.
- Installation and Maintenance: Installing a supercharger is simpler and more cost-effective than a turbocharger. Superchargers can be bolted to the top or side of the engine, needing less extensive modification. Moreover, they are generally easier to service and maintain.
- Aircraft Applications: Superchargers are commonly used in aircraft engines, especially in high-altitude conditions where there is less oxygen for combustion. This innovation allows airplanes to maintain engine performance at higher altitudes, contributing to their efficiency and functionality.
- Cooling Considerations: While modern turbochargers have automated cooling systems, superchargers benefit from a good warm-up for optimal efficiency. They work most efficiently at normal operating temperatures.
In summary, superchargers offer immediate power, avoid lag, and are relatively easier to install and maintain compared to turbochargers. Their versatility is evident in applications ranging from automotive performance enhancements to aviation, where consistent power at high altitudes is crucial.
Disadvantages of Superchargers
- Power Consumption: The significant drawback of superchargers lies in their design – being crankshaft-driven, they consume engine horsepower, taking up to 20 percent of the total power output.
- Trade-off Consideration: Despite the power consumption, the trade-off is often deemed worthwhile because superchargers can generate as much as 46 percent additional horsepower, making them a valuable choice for performance enthusiasts.
- Engine Strain: Supercharging puts added strain on the engine, necessitating sturdy components to handle increased boost and larger explosions. Manufacturers address this by specifying heavy-duty components for engines designed for supercharged use, contributing to higher vehicle costs.
- Maintenance Costs: Superchargers come with higher maintenance costs compared to other systems. Additionally, manufacturers typically recommend the use of high-octane premium-grade gasoline, adding to the overall operational expenses.
- Cost-Effectiveness: Despite the disadvantages, superchargers remain the most cost-effective method for achieving significant horsepower increases. They can result in power boosts ranging from 50 to 100 percent, making them a preferred choice for applications like racing, heavy load towing, and enhancing driving excitement.
In summary, while superchargers have drawbacks such as power consumption and increased strain on the engine, their ability to deliver substantial horsepower gains often makes them a valuable and cost-effective choice for performance-oriented applications.
Video on Superchargers
FAQ’s
How does a supercharger work?
A supercharger pressurizes the air intake above atmospheric pressure, similar to a turbocharger. However, it differs in that it’s mechanically powered by a belt or chain drive connected to the engine’s crankshaft.
What is the difference between turbocharger and supercharger?
The distinction between a supercharger and a turbocharger lies in their energy sources. Turbochargers rely on exhaust gas flow to drive a turbine, while superchargers are mechanically powered by a belt or chain connected to the engine’s crankshaft.
How much faster does a supercharger make your car?
While a supercharger may not directly make your car faster, it can significantly enhance acceleration.
What is the additional horsepower typically provided by a supercharger?
A supercharger can increase a vehicle’s engine output by an average of 46%, ranging from 30 to 50%, leading to a corresponding boost in horsepower.
Are superchargers worth the money?
Superchargers offer advantages by increasing engine horsepower and making a vehicle perform as if it has a more potent engine. However, drawbacks include increased fuel consumption and added strain on the engine.
Conclusion
That was all about the parts and working of superchargers. If you have any questions, make sure to write in comments.
