The SpeedGirls Magazine


Turbos Vs. Superchargers

A Lesson in Boost 101
Turbos Vs. Superchargers

There is nothing sexier than the sound of a blower whine or turbo blow-off valve. But with both, there’s is always been the argument of: Which is better?  The turbocharger or the supercharger?  Both are ideal for creating substantial amounts of horsepower, but both systems have their pros and cons.  So today, I’m providing you a course in professor Black’s, “Boost 101.”

First.  To decide why — you must understand how.  So let’s go over a few basics.

Compressing more air and fuel into a small engine cylinder creates more thrust upon detonation.  So the more compressed air and fuel that’s forced in = the more power.  Which is what both systems do.  They force a substantial amount air into your cylinders.  Of course, the more air you push in, the more fuel you need.  So anytime a forced induction power adder is put on, you have to upgrade your fuel system to match.  But that’s another article.

The difference between how a turbocharger versus a supercharger works, is the where the air being forced comes from.  But before I talk about how the air is routed, I first need to explain how these systems mount to the engine.

For a supercharger, it can be mounted to the intake manifold (Twin Screw Style, pictured below in black), or mounted to a remote bracket system on the front of the engine (Centrifugal Style, pictured below in silver). The engine belt drives both styles.  The belt spins a pulley mounted at the end of a shaft and this shaft is what drives turbine(s) that are housed inside the casing.  (The twin-screw style has two elongated turbine shafts, while the centrifugal only utilized a single turbine.  See below)

So back to where the air is coming from.  On a supercharger, outside air is pulled through the air filter, then through the supercharger and compressed into the engine.

This difference with a turbocharger is that outside air being sucked in is actually exhaust. With a turbo, the unit works similar to a centrifugal supercharger by utilizing one turbine, but — there is no belt needed to spin the turbine. In this case, the turbine is spun by the exhaust gas pressure exiting the exhaust manifold.

So think of it as recycling.  Air is forced out of the exhaust, and back into the turbo, which spins the turbine that forces the air back into the intake manifold.  With this system, a turbo charger can be practically mounted anywhere as long as you plumb the piping to and from the unit.

So! Now that you know the basics of how these two systems work, here are some pros and cons.  Let’s start with superchargers.

Con: Superchargers take power to make power.  Being that superchargers use the engine belt to spin the turbine, this can scavenge horsepower numbers from your overall output.

Pro: Superchargers can be run without and after cooler.  Remember that compressed air becomes very hot, which in most boosted applications it’s wise to run an after cooler to cool the intake air.  But in low boost applications, most superchargers can get away with this and save space within tight areas.

Con: Centrifugal superchargers take longer to spool.  Unlike a “Roots” style supercharger, a centrifugal supercharger turbine has to reach a certain amount of RPM’s to create ideal boost.  In most cases, effective boost is not seen until about 3,000 RPMs and up.  Revving the engine to create boost is what’s called “spooling.”

Pro: Root Superchargers create boost from bottom end of the RPM range on up.  Being a roots supercharger is mounted directly to the intake, there is no lag to building the needed amount of boost.

Pro: Supercharger systems are easier to install.  Due to not requiring exhaust pluming, added plumbing for after coolers, and less operating parts, superchargers systems can be more installer friendly.

Pro: Supercharger systems are cost effective.  Due to fewer parts, a supercharger kit can be more cost effective.  Overall, any form of supercharging will be a costly endeavor. So do full research on your vehicle before making a choice.

Now let’s look at turbo’s

Pro: Turbocharger does not take horsepower to make horsepower.  Due to not utilizing the engine drive belt.  This can save a few extra horses.

Con: Turbochargers are more difficult to install.  Depending how elaborate the system is this can be true due to the extra parts of plumbing the exhaust to and from the unit.

Pro: Turbochargers can be mounted nearly anywhere.  In most cases yes.  But more fabrication will be required to achieve custom mounting location.

Con: Turbochargers have to be after cooled or intercooled.  Due to the extreme heat from exhaust gases, it is always wise to run a cooler with a turbocharger.

So if you made it this far, you’ve been a very good student. Now it’s time for your special reward  —  start looking at a kit for your ride!  What did you think I would say?  So don’t get ahead of your self, these here are just the basics, and there’s still the fuel system and tuning to think about.