I had a 1992 Eagle Talon TSI in high school that looked exactly like the image above. It was turbocharged. It didn’t have an intercooler. It ran fine without it.
An intercooler cools down compressed air from the turbo. My car definitely could have used it.
You don’t have to know everything about turbo technology.
But a little knowledge can go a long way in helping you make the best choice for your vehicle, and your budget.
Let’s look at what a turbo and intercooler are.
As well as some of their pros and cons to help you decide whether or not its best to run a turbo without an intercooler.
Turbos and Superchargers
There are two ways for an internal combustion engine to produce power. There’s the naturally aspirated way in which the engine makes power on its own.
And there’s the forced induction way which forces air into the engine via a turbocharger or supercharger.
Turbhochargers are designed to improve the efficiency of an engine and increase performance. While they used to almost exclusively be the domain of performance vehicles.
Some of the latest economy cars featuring turbochargers include the Chevrolet Cruze, Hyundai Sonata and Nissan Altima.
Turbos are made of two halves joined together by a shaft. Hot exhaust gases from an engine spin the turbine on one half of the turbo.
A shaft connects that turbine to another turbine on the other half of the turbo. This spinning sucks in cooler ambient air into the compressor housing before discharging it into the engine.
Superchargers are air compressors that like turbos force air into the combustion chamber of an engine. There are two types of superchargers:
Mechanical superchargers are usually belt driven by a shaft, gearing or a chain connected to the engine’s crankshaft.
This type of supercharger requires a physical link to the engine to provide boost, unlike turbochargers.
Electronic superchargers work with turbochargers. This type of supercharger doesn’t require a physical link to the engine.
Instead, it serves to provide response and boost at low RPMs while the turbo builds boost. Then once the turbo reaches operational speed, it takes over boosting operations.
Since there’s no physical link to the crankshaft. Vehicles featuring electric superchargers have larger alternators and a 48-volt hybrid system to power the supercharger.
Forced induction whether from a turbo or supercharger compresses air making the oxygen molecules dense before it gets into the cylinders of an engine.
By squeezing this compressed air into the cylinders, the engine can create more power.
But this process of compressing air creates heat. A lot of heat. Like 1,875 degrees Fahrenheit (1,025 degrees Celsius).
Without forced induction an engine only reaches a top temperature of 1.400 degrees Fahrenheit (760 degrees Celsius).
To fix this paradox, an intercooler is designed to cool compressed air created by forced induction before it makes it makes it into the cylinders.
As you can see from the temperatures above, internal combustion engines produce an awesome amount of heat.
Heat soak is a term used in the tuning community to describe when an engine creates more heat than the cooling system can eliminate.
This phenomenon, of course, robs your engine of power.
But while intercoolers are beneficial for exchanging heat in vehicles with forced induction. In an engine without a turbo or superchager, an intercooler is virtually useless.
Driving Without an Intercooler
As I mentioned in the introduction, my stock Eagle Talon TSI came with a factory turbo but no intercooler.
Many more cars today come with turbocharged engines to improve efficiency but no intercooler.
While you can run a turbo without an intercooler, the caveat is that you are limited by the amount of boost you can run to keep the engine from blowing up and other damage to your engine.
Generally speaking, in order for a turbocharged engine to run safely without an intercooler means boost has to be within 3 to 5 PSI (pounds per square inch).
That, and/or it must be a low compression engine in the case of an economy car like the Chevy Cruze.
Which is why cars like this don’t require high octane fuel.
My Eagle Talon required high octane fuel because as you can imagine, being a sports car, it had a high compression engine.
Why do turbocharged, high compression engines require higher octane?
Because low octane fuel detonates easily. Higher octane fuel in a situation where more oxygen is forced into the cylinders retards detonation until after the spark, preventing damage to your engine.
Benefits of an Intercooler
- While a turbocharger or supercharger can do a lot to increase the horsepower of an engine. Intercoolers are also a vital component for horsepower gains which we’ll get into later.
- By regulating the temperature of the compressed air, you increase the reliability of the engine by ensuring a richer air-to-fuel mixture.
Intercoolers and Horsepower Gains
How much of a horsepower gain you can expect from the addition of an intercooler depends on:
- the size and type of intercooler,
- the air pressure drop caused by the design of the intercooler and its piping
- and how the intercooler is positioned within the engine.
Intercoolers aim for a 70% efficiency in their ability to cool compressed air from a turbo or supercharger.
Depending on the variables above, you can expect an additional 5% to 10% horsepower gain after adding an intercooler to your turbo or supercharged setup.
Boost Needed to Make an Intercooler Worth It
Again, for an engine that’s not supported by forced induction, you don’t need an intercooler.
That’s because as we said earlier the temperature of a naturally aspirated engine only gets up to about 1,400 degrees Fahrenheit.
While that’s hotter than you and I can touch without scalding. It’s well within the range that the stock radiator and cooling systems are designed to handle.
Intercoolers are all about heat management to prevent premature detonation.
It stands to reason that the higher the psi of a turbocharger. The hotter the compressed air since the action of compressing the air increases temperatures.
Therefore, the maximum psi you can safely run a turbo without an intercooler is 4 to 5.
But without cooling the compressed air before it gets into the cylinders you wind up robbing your engine of power it could have otherwise received from the forced induction.
Even turbocharged and supercharged vehicles that come with OEM intercoolers have their limits when it comes to boost.
The BMW F30, for instance, comes with the S55 twin-scroll turbos and a stock intercooler that’s barely adequate. That’s why boost is limited to about 18 psi.
Types of Intercoolers
There are two types of intercoolers:
Air-to-air intercoolers like the Frostbite intercooler above rely on the flow of air to the cores to cool compressed air. The design is simple with one end (the inlet) connected to the turbo or supercharger and the other end (the outlet) connected to the engine. This is the most common and the cheapest type of intercooler. It’s also easy to install and maintain.
Air-to-water intercoolers use water to lower the temperature of the compressed air. As such, the design is more complicated requiring additional components like an auxiliary radiator, water pump, water reservoir and thermostat to work. They’re pricier and installation is more involved which is why you’ll mostly find this setup in high powered race cars.
How you mount an intercooler is equally as important as the type you choose.
To work optimally, the intercooler needs to be positioned in a place where it can receive the most amount of cool air.
Front-mounted intercoolers are usually in front of the radiator.
They’re the biggest type of intercoolers stretching across the front of a vehicle to deliver some serious horsepower gains.
Top-mounted intercoolers are placed on top of the engine.
Vehicles with this type of intercooler have hood scoops to force air into the intercooler and engine, think Subaru WRX.
In the Event of Intercooler Failure
To get cool air into the intercooler often means these systems are positioned at a location that exposes them to road debris and damage, which can cause premature failure.
You’ll know when an intercooler isn’t working as it should because you’ll feel a noticeable drop in performance.
And like the technology supporting Saab cars, this could mean that issues with the intercooler have also affected the turbo or supercharger.
Other issues include an increase in fuel consumption.
One of the reasons why auto manufacturers have adopted turbochargers into their vehicles is to increase the efficiency of the engine, which includes higher MPGs.
So, if you notice an uptick in the fuel consumption of your turbo or supercharged vehicle, this could be a sign that the intercooler has malfunctioned which can also affect emissions.
Yet another sign of intercooler failure is unnatural smoke coming from the exhaust system.
When you see unnatural smoke coming from a tail pipe, the first thought usually goes toward a head gasket in need of replacement.
But it could actually be the result of an unbalanced fuel-to-air mixture ratio.
Intercooler failure is usually the result of a clogged system or leakage caused by high pressure.
Turbochargers and Engine Longevity
With all this talk of forced induction and additional heat management.
It should probably come as no surprise that turbocharged and supercharged engines aren’t as reliable as naturally aspirated engines.
Anything that requires more parts to work means there are more points for things to go wrong. That’s why a Lexus will always be more reliable than a BMW, for example.
That said, as automakers are taxed with ever stringent regulations for efficiency and emissions. One of the ways they’re gaining the advantage is by incorporating turbos into smaller engines.
By taking the otherwise wasted exhaust gases and turning it into more power, these engines are more efficient than ever before.
Traditionally, because of the stress a turbo can place on an engine. Turbocharged engines required more maintenance.
My Eagle Talon sure did, which was one of the reasons I was forced to get rid of it.
But new turbocharged engines are designed with the longevity of naturally aspirated engines.
Even upgrading a car with an OEM intercooler will improve more than performance in a turbocharged or supercharged engine.