Engines with a forced induction system don’t really need an intercooler.
My 1992 Eagle Talon TSI came from the factory with a turbocharger, but no intercooler.
Although it was a turbo and not a supercharger, we’re still talking forced air induction. However, most new vehicles today with forced induction come with an intercooler or charge air cooler.
Because an intercooler helps prolong the life of the engine. Whether a supercharger needs an intercooler depends on if it’s a Roots, twin screw or centrifugal supercharger.
In what follows we’ll take a closer look at the supercharger and intercooler to determine if the supercharger in your vehicle requires an intercooler.
What’s a Supercharger?
A supercharger is a mechanical or electronic air compressor used to increase the amount of air going into an engine.
The more air that goes into an engine, the more horsepower it’s able to create. And the less fuel it has to use.
A supercharger bolts right on top of an engine to force more air into the cylinders. Mechanical superchargers are the most common.
A supercharger is designed to produce more power in an internal combustion engine. There are three main types of superchargers:
The Roots Type Supercharger
A Roots supercharger is one of the oldest designs for superchargers. It gets its name from the brothers that created it.
Roots superchargers utilize two lobes that mesh together. These lobes can be either straight or twisted.
This type of supercharger is mechanically powered by its connection to the crankshaft.
As the lobes rotate by the engine belt, they turn in opposite directions. Air comes in through the inlet side of the supercharger where it gets compressed between the lobes.
The compressed air gets discharged directly into the engine through the outlet manifold.
Twin Screw Superchargers
The twin screw supercharger is similar to a Roots supercharger in that it’s also driven by a belt or gear connected to the crankshaft.
But a twin screw supercharger is more efficient.
It uses a pair of identical spiral rotors and a combination of suction and compression to force air into the engine.
Unlike a Roots supercharger that just pulls air in through the inlet side and pushes compressed air out through the outlet side. A twin screw supercharger compresses air between the rotors like a Roots supercharger.
But instead of the compressed air moving vertically into the engine.
It moves horizontally to the discharge side of the supercharger where it then goes into an intercooler before getting discharged into the engine.
These superchargers are more widely used than displacement superchargers like the two examples above.
A centrifugal supercharger looks like the compressor side of a turbocharger.
But like most superchargers, its belt or chain driven by an engine’s crankshaft.
Once a centrifugal supercharger is in motion. The impeller rotates at a high rate of speed sucking air into the supercharger.
Inside, a diffuser compresses the air through centrifugal force.
Like twin screw superchargers, the compressed air then gets sent to an intercooler. From there, the cooled compressed air gets sent into the engine during a piston’s downward stroke.
What’s an Intercooler?
An intercooler as the name implies is used to cool the intake air on engines with forced induction, like superchargers and turbochargers.
The byproduct of compressed air is heat. The presence of heat means there’s less oxygen going into the engine.
An intercooler’s job is to cool down compressed air from a turbo or supercharger before it goes into the engine.
Cooling the hot compressed air provides more oxygen for the cylinders, improving combustion which improves horsepower. There are two main types of intercoolers:
This type of intercooler works by passing compressed air through small tubes past a series of cooling fins. Heat gets transferred from the compressed air into the cooling fins.
From the intercooler the cooled compressed air is fed into the engine through the intake manifold.
Air-to-air intercoolers are lightweight.
But they’re big and usually sit at the front of an engine where there is better airflow and the most access to cooler air.
They’re also cheaper than the next type of intercooler we’re going to talk about, which is one of the reasons why air-to-air intercoolers are often the most popular option.
These intercoolers are more complicated.
An air-to-water intercooler uses water to cool compressed air. As cool water gets pumped into the intercooler, it extracts heat from the compressed air.
The heated water gets pumped into a radiator where it’s cooled before it’s recirculated. As complicated as air-to-water intercoolers are, they take up less room than air-to-air intercoolers.
This makes them the perfect choice for vehicles where space in the engine bay is at a premium. And since water conducts heat better than air, it can handle a wider range of temperatures.
What Type of Supercharger Needs an Intercooler?
After our brief survey of the different types of the three main mechanical superchargers and how they function. The answer should stick out like a sore thumb.
Both twin screw superchargers and centrifugal superchargers utilize intercoolers as part of their design to cool down compressed air before it’s passed into the combustion chamber of an engine.
The only supercharger from our list that doesn’t incorporate some kind of intercooler into the design is also the oldest.
A Roots supercharger would benefit the most from an intercooler because it heats up compressed air to higher degrees than even a turbo.
The type of intercooler you’ll want to incorporate with this type of intercooler is an air-to-water intercooler.
Why An Air-to-Water Intercooler?
Supercharger cooling is important for engine power and durability.
Given the design of a supercharger and an air-to-air intercooler, there’s really no place to put this type of intercooler.
Secondly, as we said water conducts heat better than air – water will do a better job of cooling hot compressed air from the Roots supercharger than just air.
The only issue left to overcome would be mounting the air-to-water intercooler before the compressed air makes it into the engine.