The natural world is a good thing––after all, we live there––but sometimes it needs a little help, like when it comes to engine performance. Naturally aspirated engines rely on atmospheric pressure to fill the cylinder when the intake valve opens and the piston moves downward in the bore. But nature has its limits, and the more air you want to pump into your engine, the more you have to juggle cam timing and other factors that can make an engine a screamer on the track but a dud on the street.
One alternative is to connect an air pump––either a turbocharger or a supercharger––to the engine to do what nature can’t. Turbochargers and superchargers do the same job, but they go about it in different ways, and it’s important to know the pros and cons of each before you decide which path to power works best for you.
Turbos are often called “free power” because they use the engine’s exhaust gas to spin a small turbine that forces air into the intake system. The turbo is plumbed in line with the exhaust system, so the higher the engine revs, the faster the turbo spins, and the more air it pumps into the engine.
Turbos are relatively simple to install, but they suffer from what’s called turbo lag, which is the time it takes for the exhaust gas to spin up the turbo. Lag is most noticeable from a standing start when the engine is idling, but it can also show up when you want to pass another car and you mash the throttle––and nothing happens until the turbo spins up. Finally, since they’re connected to the exhaust system, turbos generate a lot of heat. A tight engine bay might need to be insulated to protect other underhood components.
Superchargers do the same job as turbos, but go about it differently. Instead of being plumbed into the exhaust system and spun up by exhaust gas, they’re belt-driven by the crankshaft, so they spin up as fast as the engine does with none of the lag of a turbo, and nowhere near as much heat.
Superchargers have their own drawbacks, however. It takes power to run them, making adding one to your engine a sort of two-steps-forward-one-step-backward proposition. And because they’re driven by the crank, the mounting options inside the engine bay are limited to those that have access to the front pulley.
Turbos are winning the war for car manufacturers’ hearts because they’re easy to add to existing small-displacement engines to boost power output, and because a properly sized turbo on a small engine doesn’t have a lot of lag, making it easier to drive on the street. But superchargers still rule the quarter-mile, where big-displacement engines are the norm and instant torque off the line is vital to a winning ET.