A few months ago we presented a brief history of superchargers and turbos. (Find that guide here.) We’re back with a break down of these two setups and some side-by-side comparison to help determine which one packs a better punch.
So, What’s the Difference?
Let’s be honest, superchargers and turbos mostly do the same thing. But they are different in one critical functional arena: the area in the rev-range where they add the most additional power. Superchargers are belt-driven, so they produce a boost as soon as you press the throttle. As rpms increase, however, superchargers add extra strain on an engine, because it uses power to run the supercharger. Therefore, superchargers are best for engines that have peak power at lower rpms. That is, larger displacement engines with redlines below 6,500-7,000 rpm.
On the other hand, turbos need to “spool up,” which means they need to have enough exhaust gasses moving through the turbo to create a boost that will increase engine performance. These gasses come at higher rpms. Since turbos drive on exhaust gasses, rather than a belt, they essentially cost no power to run and are more efficient than superchargers. If an engine needs to be wound out more (i.e., smaller displacement powerplants), then a turbocharger is a more logical choice.
This is another area were you need to be honest with yourself when selecting a turbo. Don’t pick the biggest one just for ‘bragging rights’, you’ll end up disappointed with how your setup preforms. “Tubo Lag or the time to “Spool up” isn’t really a concern if you have a cam designed for a properly sized turbo for your setup. I know, here we are talking about a properly spec’d cam again….Also with devices such as a 2 step rev limiter coupled with a good torque converter, turbo lag isn’t even on my mind. For example, once my car is staged, I can get it up to 3500RPM and building 5+ PSI of boost in under 2 seconds waiting to launch,” said John Potucek, a lifelong gearhead and Product Master Data Speed Team Lead at Keystone Automotive.
Exceptions to the Rule
Keep in mind however, these aren’t universal truths. From 2005-2007, Chevrolet fitted a Roots-type supercharger to its 2.0-liter Cobalt SS sport compact for the sake of more power in the rev-range. Also, Mercedes-Benz fits two turbos to the big 6.0-liter V12 found in the current AMG version of its S-Class sedan for the sake of higher efficiency.
And there are, in some rare cases, examples of engines with both supercharging and turbocharging present. Volvo’s newer 2.0-liter four-cylinder T6 engine, for example, does this. This type of setup has the benefit of the low-rpm boost of the supercharger and the high-rpm boost of a turbo. But it comes at the added cost of additional weight from using both systems.
In the end, turbochargers are generally better at producing a higher-rpm power increase and respectable fuel economy. As far as maintenance goes, they typically require more frequent oil changes since they generate more heat. Superchargers are better suited to larger displacement, lower-rpm engines where fuel economy is less important. Maintaining a supercharged engine usually requires supercharger belt changes and more frequent air filter inspections and changes.
After running both, I’m partial to turbochargers now. Something about the sound and the way the power comes in, I can’t ever see me going non-turbo on my car,” added Potucek.
Regardless of the route you take, if a forced-aspiration induction appeals to you for your ride, there are plenty of kits available in the aftermarket. Companies like COBB, Edelbrock, Greddy, JDM, Paxton, ProCharger, and Whipple are just a portion of the suppliers to choose from when deciding between superchargers and turbos.