Boost Your Fun

They look cool, boost power, and use the exhaust stream to operate. Yes, we're talking about turbochargers. With the proper selection of parts, tuning, and installation, a turbocharger can transform your engine into a stormer that produces exceptional power without sacrificing driveability and fuel economy.

Walk the aisles of any new car show and you'll find the bulk of the latest performance iron fitted with turbochargers. These exhaust-propelled power adders are nothing new to domestic-car lineups--in the '60s, Chevrolet installed turbochargers on thousands of Corvairs to raise power ratings about 50 percent at the crankshaft. But in the hot-rodding world, we're more interested in what these power adders can do for our own automotive creations.

During our many visits to racetracks and car shows this year, we saw numerous turbocharged engines producing exceptional power while remaining very streetable. Some of these examples even had small-displacement powerplants with (dare we say) less than eight cylinders. We went right to the turbocharger experts to learn more. In this story we'll tell you what we found and explore what's available to give your engine a boost.

Power Boost

Generally speaking, blowers add power by increasing the amount of airflow into an engine's intake system. In a normally aspirated engine, air enters the intake at normal atmospheric pressure (approximately 14.7 psi at sea level). A turbocharger uses the energy from the exhaust stream to raise the pressure of the air flowing into the intake system. This increases the amount of air delivered to the combustion chamber, which in turn can burn more fuel. The results can be astounding, offering the performance enthusiast more power throughout the rpm band.

Turbocharger designs vary by manufacturers, but all use a compressor on one end and a turbine on the other. The turbo assembly uses seals to prevent high-pressure gases from leaking. Centrifugal compressors use three components that must be matched to the vehicle's performance profile. These are the impeller, the diffuser, and the housing.

The compressor impeller spins at high rpm and uses centrifugal force to accelerate the air traveling through it. The turbocharger's diffuser operates like a nozzle in reverse, slowing and stabilizing the air and causing the pressure to increase. The turbocharger housing directs this high-pressure air. Like any other performance part, the design and shape will alter the performance level.