The power generated by the internal combustion engine is directly related to the amount of air that is compressed in the cylinders. In other words, the greater the compression, the greater output of the engine.

Two approaches can be used to increase engine compression. One is to modify the engine to increase the compression ratio. This has been done in many ways including the use of such things as domes or high top pistons, altered crankshaft strokes, or changes in the shape and structure of the combustion chamber.

Another, less expensive way to increase compression (and engine power) without physically changing the shape of the combustion chamber is to simply increase the intake charge. By pressurizing the intake mixture before it enters the cylinder, more air and fuel molecules can be packed into combustion chamber.

Turbocharger Lag

Increases in horsepower are normally evidenced by an engine¡¯s response to a quick opening of the throttle. The lack of throttle response is felt with some turbocharged systems. This delay or turbo-lag occurs because exhaust gas require a little time to build enough energy to spin the blower up to speed.

The variable nozzle turbine (VNT) has greatly improved the turbo-lag traditionally associated with turbochargers. Turbo lag occurs when the turbocharger is unable to meet immediate demands of the engine. This causes the power from the engine to temporarily lag behind the need. VNT units allow the turbine to accelerate more quickly than the conventional turbos thereby reducing the lag time.