In internal combustion engines, forced induction can either improve efficiency or increase the power output of an engine. It can be done in two ways: Turbocharging or Supercharging. But which type of forced induction is best? By now, most people would have a rough understanding of how a supercharger and turbocharger works. But if you don’t, you can click on the links below to find out more.
Now we’ve covered how both types of forced induction methods work, we know that turbochargers and superchargers essentially do the same task, but in very different ways. It all depends on the application and the type of car that the engine is being fitted to. Which begs the question, which is better? But in all honesty, there is no definite answer to that question.
These days, turbocharged engines are commonplace. You’d be hard pressed to name any production car brand that doesn’t have a turbocharged powertrain in their lineup. On the flipside, naturally aspirated engines are slowly diminishing, while supercharged engines are even rarer than that.
For instance, muscle cars or cars built for drag races require power on tap the second the driver’s foot mashes the throttle. In a turbocharged engine, it would take too much time for boost to build up. Hence, dragsters often opt for superchargers. Conversely, rally championship cars are able to fully utilise turbos because straight line speed times aren’t as crucial, but the turbochargers can be calibrated depending on the ambient air temperature and density in different countries.
Superchargers can generate more boost at lower RPMs than turbochargers can. And the powerband for a supercharger is more consistent and liner than a turbo. But at higher RPMs, turbochargers are able to produce more power due to the build-up of exhaust gasses. But because of the pent-up heat from the exhaust manifold, the turbochargers have to be well insulated.
Now, there a wide range of turbocharger setups. Single or twin scroll, twin turbocharged/bi-turbo, quad turbo setups, and hot-vee setups. Historically, turbochargers are notorious for reducing throttle response times due to the turbo lag, but modern factory fitted turbocharged engines are less prone to these issues. And turbochargers allow manufacturers to fit smaller displacement engines into their cars, while supercharged engines generally require larger engines to cope with the power needed.
However, there is a third option that a few manufactures have used. And that is Twin charging, which uses both a turbo charger and a supercharger in tandem. In twin charged engines, the two systems are designed to mitigate the drawbacks of each other.
Essentially, it reduces the throttle response by using the supercharger to boost power during the turbo “lag”, and then the turbo boost kicks in once the turbine gets up to speed. A twin charged system also minimises the power sapped by the supercharger at higher RPMs.
However, twin charged systems are usually expensive. And in the past, the cost of developing and producing such systems for production cars are not justified. But certain manufacturers are beginning to adopt twin charged engines for their production cars. Examples of which include Volvo’s T6 or T8 engines in the S90/V9, XC60 and XC90 models, and Volkswagens that use the 1.4L TSI engines.
Essentially, different types of cars have different horsepower and torque requirements. There is no definitive answer as to which is best. But there is a reason why most manufacturers choose to fit turbochargers instead of superchargers. And that has to do with the overall efficiency of the two systems. But that’s not to say that superchargers can’t be as practical or efficient.
At the end of the day, exhaust gasses are basically “free energy” ready for the taking. Some manufacturers may prefer not to hold their engines back by strapping a supercharger to it. Not when they can use exiting exhaust gasses to get massive power gains. In the name of efficiency, turbos are the more practical solution.