Introduction

• To understand how a blower or super charger works, it is important to have knowledge of engine displacement. When an engine is described in cubic inches or liters it has nothing to do with the size of the engine. What is being referred to is how many cubic inches of air each cylinder displaces. It is the volume within the cylinders. A 302-cubic inch engine displaces 302 cubic inches of air. When an engine's horsepower is being increased, essentially the cubic inches in the cylinders are being expanded.
  
  

Types

• There are several types of blowers. The oldest and still widely used is the top roots type blower. This blower sits on the top of the engine in place of the intake manifold and is driven by a belt on the crankshaft. The next type is the centrifugal charger that sits in the front of the motor near the alternator. It looks like an alternator to a degree. These are also belt driven. The last type is the turbo charger that is so predominant on the new vehicles. This unit looks much like a snail and is driven on one side by the pressure of the exhaust and the other side intakes and pressurizes the air to the cylinders.
  
  

How it Works

• A normally aspirated engine relies on the vacuum from the engine during the intake stroke to pull fuel into the engine. This can vary due to altitude, air density or humidity and temperature of the air. The higher the car is above sea level, the thinner the air. The more humidity the thinner the air due to the replacement of air by moisture. The temperature of the air also makes a difference since warmer air is less dense than colder air. A car engine will change its power output directly proportionate to these factors. Fuel injection has the advantage over a carburetor in as much as it is not reliant on vacuum for fuel flow, although it is still effected by the differences in the air.
  
  

• A blower or super charger is a mechanism that uses a system of rollers or veins turned by either the engine using a belt, or by the exhaust (as with turbos). These mechanisms compress the air in the intake manifold and pack it in the engine with force, effectively increasing the cubic inch displacement of the engine by increasing the charge in the cylinders. This boost in fuel and air being pushed into the manifold increases power dramatically. In most cases it can add from 40 percent to over 100 percent power increase.