The street-racing scene in the United States has grown to an all-time high and is still growing towards an unknown paramount. Car enthusiasts put in vast amounts of time, labor, and money to modify their cars. Their goal is to dominate the streets by having the fastest and most powerful car, so they can have the right to brag. As a result, the debate over turbocharging or supercharging a car engine for power was bom. Both of these types of engine modifications share similarities, but at the same time they differ vastly.
Turbocharging is usually the preference of engineering purists because it captures wasted exhaust energy and puts it to work. Because less wasted energy equals higher efficiency, a turbo- aspirated engine is extremely efficient because of its use of exhaust waste. A turbocharged engine uses a centrifugal compressor, which is basically a fan with its blades reversed so that air is being sucked instead of being blown out.
In a turbocharger, the wasted heat energy of the exhaust stream is directed so that it is used to compress air taken in from the outside. This compression of air creates power and, at the same time, more heat in the exhaust. The newly created exhaust heat is then taken to compress more air, which creates more power and more heat, which creates a continuous cycle. This cycle creates boost and dramatically increases the power of an engine. The horsepower gain from the addition of turbo runs from approximately fifty to ninety horsepower. Because the exhaust drives a turbo, the exhaust and intake air both have to be routed to the centrifugal processor.
This causes problems because complex plumbing has to be done to bring the air intake and exhaust systems to the same place. This requires plenty of engine room for pipes and wires to be run so that point A can be connected to point B. A secondary problem is the centrifugal compressor has to be spinning quite fast before it can effectively move air for compression. Getting the compressor up to the required speed takes a certain exhaust and intake volume. In order for these volumes to be reached, the car needs to have a high acceleration rate. This creates lag, or a period of wait time before the turbo actually kicks in.
A centrifugal processor also runs a supercharger. However, instead of being driven by exhaust waste, the supercharger uses the crankshaft to compress air. Since exhaust waste is never used a supercharged engine efficiency is considerably lower that that of a turbocharged engine. Because of this lowered efficiency, the horsepower gain spectrum is decreased to about fifty to seventy horsepower. Although efficiency is lowered, the plumbing problems disappear because the exhaust and air intake systems never have to meet.
This eliminates the issue of needing engine space, so packaging tends to be easier with superchargers. The crankshaft is what transfers the power created by the pistons to the transmission, which is eventually transferred to the wheels. This means that the crankshaft is constantly moving as long as the car is accelerating, so the centrifugal speed is mechanically linked to the engine speed. This eliminates the lag experienced with turbo and boost is available almost immediately.
The turbocharging versus supercharging debate has been raging for as long as men and cars have existed. Most of these debates eventually break down to each party yelling ?Turbo lag!? or ? Low efficiency!? The argument will never have its clear winner. Each modification has its advantages and disadvantages, but the natural human instinct is to pick a favorite and defend it with religious conviction.
