[scottyp]

Types of Superchargers: Below are the 3 main types of superchargers and some of their characteristics.

Roots Type: the roots type blower is the grandfather of all superchargers. These first started showing up as early as the late 30's on large machines and eventually to drag cars and some street rods in the 40's and 50's. It totally eliminates the intake manifold and takes the place of it as it nestles on top of (or in our case to the rear of) the head(s) of the engine. The impellers are a typical fan-type impeller that create compressed air as it is fed in. The fuel delivery is generally through the top (as in V-8 engines) and is sometimes compressed with the air as it's delivered depending upon application. Some exceptions to this are the jackson racing supercharger kits which utilizes the MPFI system. Roots type blowers are the least efficient as well. They typically pull in about 50-65% volumetric efficiency depending on the impellers.

Centrifugal Type: The next generation of superchargers. These started showing up originally in the late 70's when some Drag racers were switching to fuel injection and wanted to use a supercharger. It generally sits off to a side of the engine with piping running to the intake manifold. This compressed the air before it reached the fuel delivery point making it easier to determine the fuel flow ratio without running too rich or lean. Design wise these are just turbo chargers without a turbine housing. The air comes in, through the compressor and out to the IM. They flow air more efficiently than a roots-type blower. Due to modernization, computers have really helped these along. More efficent fan-style compressors were made allowing for greater volumetric efficiency taking it up to 60-75%.

Twin Screw: How I forgot this one in the past still escapes me but a big shout to boosted J30 for reminding me. The whipple type blower is the biggest overhaul to superchargers in 30 years (at it's first inception somewhere between the late 80's and early 90's) It is also very unique and utilizes a design which would have been thought to never work before the time of computer designed parts. This bad boy uses a roots style case and gear driven, corkscrew style impellers. These impellers were designed with smooth flow, and efficiency in mind. Whipple type superchargers are the most efficient of the three with VE ranging from 70-85% at low RPM but as the RPM goes up it loses its efficiency. Cool for low end torque but the ride is over at around 4500