Of the three basic supercharger types, the Roots has historically been considered the least fuel efficient. However, recent engineering developments by Eaton Corporation have resulted in a more efficient Roots-type supercharger, known as the TVS. This new Eaton TVS design has been proven to provide isentropic efficiencies as high as 76% while providing a significantly larger efficiency island than turbochargers.. Unlike the basic illustration, most modern Roots-type superchargers incorporate three-lobe or four-lobe rotors. The latest design made by Kenne Bell, introduced for the Ford Mustang GT500 Super Snake, has four lobes per rotor, enhancing its efficiency through a reduction of pulsations.
The Roots-type supercharger is simple and widely used. It can also be more effective than alternative superchargers at developing positive intake manifold pressure (i.e., above atmospheric pressure) at low engine speeds, making it a popular choice for passenger automobile applications. Peak torque can be achieved by about 2000 rpm.
Accumulated heat is an important consideration in the operation of a compressor in an internal combustion engine. Per the ideal gas law, a compression operation will raise the temperature of the compressed output. Additionally, the operation of the compressor itself requires energy input, which is converted to heat and can be transferred to the gas through the compressor housing, heating it more. Although intercoolers are more commonly known for their use on turbochargers, superchargers may also benefit from the use of an intercooler. Internal combustion is based upon a thermodynamic cycle, and a cooler temperature of the intake charge results in a greater thermodynamic expansion and vice versa. A hot intake charge robs the engine of efficiency and produces diminishing returns from the compression process, while an intercooling stage adds complexity but can improve the efficiency by releasing some of the unneeded heat. Above about 5 psi (0.3 bar) the intercooling improvement can become dramatic. With a Roots-type supercharger, one method successfully employed is the addition of a thin heat exchanger placed between the blower and the engine. Water is circulated through it to a second unit placed near the front of the vehicle where a fan and the ambient air-stream can dissipate the collected heat.