Types of superchargers

2fast4thelaw

No problem, I will answer this to the best of my knowledge but dont hold me to being exact.

All superchargers are positive displacement and all this means is that at idle the supercharger as producing some amount of air pressure above what the engine would if it where naturally aspirated.

Roots Type:
Twin Screw and roots are very similar and are what most of us easily recognize as a big crome blower sitting on top of the engine between the valve covers of V engine. These units have 2 long cylindrical looking lobes that counter-rotate each other and they sort of interlock "without touching each other" thus squeezing the air and forcing it downward into the intake manifold. This design is efficient because the rotors are large and have relatively high air displacement without having to turn 50,000 to 100,000 rpm like centrifugal superchargers.

The difference between twin screw and roots is just the shape and design of the rotor. The the twin screw rotors are tapered at one end like a cone and the rotors ride opposite of each other. (I may be wrong on this so anyone else with expertise please correct me if I am)

Looking at the photos the roots type supercharger is pictured on the bottom left.

Examples are: Stillen, Kenne Belle,Eaton, and Whipple.


Centrifugal:
Now the other design that is commonly used is the Centrifugal chargers. These units compactly fit under the hood with little to no hood modification. Centrifugal chargers are basically the compressor half of a very large turbo that has been geared up to like 7:1 to turn very fast up to 115,000 rpm. These units are less efficient becasue the engine has to work harder to turn the impellor, which is known as parasitic loss.

Examples are: ATI-Procharger, Vortec, Paxton.

Traction Drive Centrifugal:
Some of these designs are better than others. The best designed units use a traction type planetary drive that use sets of rubber like rollers instead of gears and belts inside the drive unit. The drive system is variable based on demand. The harder the engine accelerates the more pressure is put on the rollers to spin the compressor faster. When driving at the speed limit around town the compressor is not spinning in direct link to the crankshaft so there is less load to the engine under normal driving. This not only reduces friction, but it makes for a quiter unit and ultamately more efficient.

The Traction drive supercharger is pictured on the right.

Examples are: HKS, GTM

Attached Images

	roots super-charger-fix.jpg (36.0 KB, 40 views)
	traction-drive-diagram.jpg (48.9 KB, 50 views)

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