Turbos And Superchargers

By Author: Eric Ferguson
Total Articles: 7
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Turbos and Superchargers

For the performance auto enthusiast who wants to take their vehicle to the next level, turbos and superchargers are worth considering. These engine modifications are usually (but not always) easy to install and can increase your engine's horsepower and low-end torque as well as its fuel efficiency! In addition, many turbos and superchargers that stick out above your car's hood look very cool and intimidating.

What's The Difference?

All turbos are considered superchargers - but not all superchargers are turbos.

In simplest terms, a supercharger is a device that forces greater quantities of air into the fuel mixture than would normally occur under normal circumstances with an unmodified air intake. More air means greater amounts of oxygen, which is the flammable element that allows combustion of fuel. By forcing more oxygen into the fuel mixture, it is possible to extract the maximum amount of power from every drop. (It's worth noting that without superchargers, the engines of most prop-driven aircraft wouldn't run at all due to the relative scarcity of oxygen molecules ...
... at higher altitudes.)

A turbo, or turbocharger is a specific kind of supercharger that uses the engine's exhaust gases as a power source. Other kinds of superchargers are driven by the engine's own fan belt or timing chain. These are technically known as centrifugal superchargers (the other type is called a centrifugal turbocharger).

There is yet another kind of supercharger, known as a positive displacement pump. However, these are very costly, and aren't practical for most street machines in any event (they are used primarily for dragsters and tractors used in pulling competitions).

Which is Better?

Because it is driven by the engine, superchargers have a tendency to absorb up to 33% of the kinetic energy of the motor - meaning this energy is lost before it is even used.

A turbocharger on the other hand is using the energy remaining in exhaust gases, which would otherwise be wasted. Because of this, a turbocharger provides not only a greater power boost but better fuel economy as well.

Historically, superchargers have the advantage over turbochargers in terms of throttle response. Because of a phenomenon known as turbo-spool, acceleration from the low RPM range can be sluggish because the turbocharger cannot force as much air into the mixture at this point. However, technological advances have made possible the production of turbochargers with which the throttle response is not significantly less than that of a supercharger. In any event, the difference in throttle response between the two at high RPMs is negligible.

The biggest drawback to superchargers lies in the fact referred to above; it is driven by the vehicle's motor, so a certain amount of energy is wasted. The presence of a supercharger also places additional demands on the engine and drive train components, so they may not be suitable for smaller engines. Another disadvantage to superchargers is maintenance cost; most manufacturers recommend the use of more expensive premium gasoline for use in supercharged engines.

Nonetheless, if you're looking for a reasonably priced way to increase your engine's horsepower output by anywhere from 50 to 100% without internal modifications, a supercharger is definitely the way to go.

Eric Ferguson
ericferguson@andysautosport.com
408-263-9207 x106
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