How does a turbo operate?

Turbocharging is one of the less expensive ways of helping an engine generate more horsepower. A turbocharger should not be confused with a blower or supercharger (blowers/superchargers are usually belt driven and actually USE horsepower to generate boost pressure).

After the engine combusts the air/fuel mixture in the cylinder, it is expelled through the exhaust valve(s) in to the exhaust manifold. In a normally aspirated (non turbo) engine, the exhaust manifold or header is attached to the exhaust system. In a turbo charged engine, however, the turbo charger sits between the header and the exhaust system.

The exhaust gas is forced through the turbo where it drives a turbine wheel on it's way out the exhaust system. The turbine wheel is attached to a shaft that rides on floating bearings and drives a compressor wheel. The compressor wheel is what ?turbo charges? the engine as it pulls air through the air intake system (pre-combustion) and channels it through a compressor housing, where it is compressed and directed into the engine intake manifold. By compressing air before it enter the cylinder, you can increase the density of the air/fuel mixture and create a more powerful explosion within the cylinder for greater power. The amount of "BOOST" or compressed air generated by a turbo is determined by its design, which is usually determined by the engine requirements.

How does a turbo create more horsepower?

Horsepower is generated by the optimum burn of the fuel which is directly related to the fuel/air mixture. If extra air is added to the cylinder extra fuel can also be added to maintain optimal ?burn? for more powerful combustion.

A factory turbocharged engine is designed to handle the extra fuel allowed with the added air. When installing a turbo to a non-turbo (naturally aspirated) engine, caution should be taken to assure that the system has been engineered so as not to cause engine damage.

What is a WASTEGATE and how does it work?

A wastegate is a device that bypasses some exhaust flow around the turbine section of a turbocharger to control maximum boost. The wastegate is typically controlled by a pressure actuator that is connected to manifold pressure. This keeps the turbo from over-boosting at the top end.

Under normal conditions, the wastegate is held shut by a spring inside the actuator canister. When boost pressure reaches factory limits, the actuator progressively opens the wastegate, allowing exhaust flow to bypass the turbine, thus regulating manifold boost pressure.

On poorly designed, low cost factory wastegates turbine inlet pressure that can overpower the spring in the actuator, and forcing the wastegate open at lower than intended boost levels. In some cases an aftermarket wastegate actuator help maintain elevated (desired?like when your engine is ?chipped?) boost levels.

The net affect is that the turbocharger comes up to peak boost more quickly and then maintains that boost level throughout the engine?s RPM range for optimum mid-range torque and top end performance.