What are the differences between Turbo’s and Superchargers?
Forced Induction Differences
A turbocharger uses hot exhaust gases to spin its turbine wheel, at speeds that will vary based on the exhaust pressure, that is connected by a short shaft to an impeller wheel inside the compressor housing. The impeller sucks air into the turbo housing, compresses it and pushes it into the engine to create boost pressure. As it is compressed, the air gets hot, so the air exiting the turbo is usually routed through an air-to-air or air-to-water heat exchanger called an “intercooler.”
Boost pressure is controlled by a “waste gate” that opens to vent pressure once a certain level of boost has been achieved.
Turbo kits are available for many popular applications and greatly simplify installation issues by providing all of the hardware and plumbing that is needed to fit a particular vehicle, including higher flow fuel injectors, a higher flow fuel pump in some cases and a special tuner tool for recalibrating the ECM.
Supercharging, by comparison, typically provides more instant throttle response depending on the type of supercharger that is used. A supercharger is a belt-driven blower so it is somewhat less efficient than a turbo because it takes power from the engine to drive the blower. A turbo gets its drive energy for free from the exhaust but also creates a small amount of power-reducing backpressure that has to be overcome before it develops boost and starts to make power, otherwise termed at turbo lag.
A “positive displacement” supercharger (also called a “Roots” style blower) — like that on the ZR1 Corvette, GT 500 Shelby Mustangs, Roush Mustangs and many street rods — has counter-rotating lobed rotors that force air into the engine. The boost pressure developed depends on engine speed and the underdrive ratio of the pulley on the supercharger.
By comparison, a “centrifugal” supercharger does not have counter-rotating rotors, but uses a compressor design similar to the impeller wheel on a turbocharger. Boost builds with rpm more like a turbo, but throttle response is better because of the belt-drive setup.
Supercharger kits are available for many popular street engines and typically offer a boost in performance of 150 to 200 or more horsepower — which most stock blocks can handle. But additional modifications become necessary to maintain engine reliability with higher levels of boost, as well as safety precautions such as enhanced brake systems.
More about engine and other vehicle systems modifications coming in future posts of this series. So stay tuned for more to come!