There are threads going concerning intercoolers, which made me realize I never thought about their operation, and it looks like I'm not the only one a little foggy on this. So I called some Ford service departments.

Here's the way I understand it: Air passes thru the air filter, then the compressor stage of the turbo where it is "boosted." It passes by the intercooler, then into the manifold and combustion chamber.

I picture the turbo as being like a jet engine. You have the compressor section, which compresses air as it passes thru the blades.

The other end of this spinning shaft is called the turbine section, and it's stuck in the exhaust system, and that provides the power to spin the shaft.

When you compress air, it makes the temp rise, and hot air going into the combustion chamber is inefficient, so an intercooler is used to cool that air, which will also
cause moisture to condense out.

I picture the intercooler as a radiator like device, thru which this hot boosted air passes and is cooled. And it's cooled because inside of it, we have a completely separate air flow system. This airflow enters thru the big hole where the license plate should be, flows thru ducting into this "radiator" and them flows out of it into the engine bay. It is a completely separate air flow system from what goes thru the turbos and into the engine.

I just talked to a Ford service guy, and he said there is a "dryer" in the Ford system, and he's never heard of any problems regarding condensation moisture off the intercooler causing engine malfunctions. I spoke with other dealers as well, and they never heard of the problem either. Keep in mind, I live in Utah, where 30% humidity causes us to start whining.

How much of this did I get right? Can anyone paint a better picture of exactly what the intercooler looks like? I've never looked under the hood and studied one; probably hard to see anything.

 

The intercooler (actually, it's technically called an aftercooler) is no different than the radiator for the cooling system. The only major difference is that instead of coolant passing through it, you have compressed air from the turbochargers.

They typically look exactly like normal radiators, but with fatter tubes.

Here is a picture of a typical intercooler, really not much to look at: https://secure.memca.com/ecodetuning...1299_small.jpg

 

The main purpose of an intercooler is to lower the temperature of air being taken into the turbo. When air is compressed in a turbo it gets hotter, so the colder you can get the air going into the turbo, the better for the engine. When you cool air after it has gone through the turbo (but before it goes into the engine) it's called a charge cooler.

There are actually two main types of intercoolers, air-to-air and air-to-water. Air-to-air is simply using air flowing through the fins of an intercooler to cool air being taken in through the intake piping. It's about as simple as you can get and has no moving parts.

Air-to-water works a lot like a radiator setup. Using a liquid to cool an air charge.

On the ecoboost, ford uses an air-to-air setup. The upside to these is that they're simple, robust, light weight, and inexpensive. The downside is they require a high volume of air flowing through the cooler to work efficiently, therefore they don't work well at lower speeds and don't work at all when you aren't moving.

Air-to-water is what they use on the GT500 Mustang to cool the air from the supercharger. These are more efficient in a wider range of operating conditions, but they're more complicated and more expensive.

As to how they route the piping on an F150, I'm not sure. If it's an intercooler, it goes:

Air enters intake>goes through filter>goes through inside of cooler>goes through cold side of turbos> goes through throttle body and into engine

If it's a charge cooler setup:
Air enters intake>goes through filter>goes through cold side of turbos>goes through inside of cooler>goes through throttle body and into engine

 

This makes no sense at all. What's the point of feeding air though a cooler that is being cooled by air that is the same temperature as the air being cooled?

 

Remember that, in most vehicles, you aren't taking in air directly from outside the vehicle (like a ram air setup does), you are instead taking it from somewhere in or near the warm engine bay. Therefore, the intake temperature is already typically higher than the ambiant air. Next, you have a cooling effect from the volume of air moving over and through the metal intercooler.....similar to how the metal finger guard over the blades of a fan feels colder than the ambient temperature.

Looking at some pictures of the Ecoboost engine, it looks like it uses a charge cooler/aftercooler setup, so it's cooling the compressed air before entering the engine.

 

Not a single vehicle has the air from the filter running through an intercooler then going to the turbo. That is completely pointless since it requires the same amount of plumbing, and will only drop the temperature maybe 10*F tops before it hits the turbo. You could do the same thing by locating the air box inlet closer to the grille or something.

Intercoolers are used between stages of turbocharging/supercharging. So if you have a sequential turbocharger setup (one turbo feeds the other), the output of the 1st turbo goes through the intercooler before it enters the 2nd turbo.

Now if you have an "intercooler" on the output of that 2nd turbo, it's technically called an aftercooler. It's also called an aftercooler if you have a single turbo, or two turbos in parallel (like an ecoboost).

Air Box/Air filter > Single Turbo/Twin Parallel Turbo > Aftercooler > Engine

or

Air Box/Air filter > first turbo > intercooler > second turbo > aftercooler > engine

But nearly everyone just refers to what are technically aftercoolers as intercoolers now.

 

For the OP: This video has good animation showing the path of intake air and exhaust through the turbo system.

How a turbo works - YouTube

As mentioned in the video, air temperature at discharge of turbo is quite hot (maybe twice the temperature of boiling water). The intercooler is used to cool the air charge before it enters the engine. If you go look at your intercooler then you'll pretty much see the mechanics of it -- It's just a bunch of metal tubes that span from side to side. The turbo charged air is 'hot' and the surrounding ambient air is 'cold'. As the 'hot' air passes through the metal tubes there is temperature reduction by means of heat transfer through the metal tubes and into the 'cold' atmosphere. The reason an intercooler has a bunch of small tubes, instead of one large tube, is to increase surface area where heat transfer can occur from hot air to cold air, and that causes greater temperature drop by the time the air reaches the engine.

I've never done an analysis on a turbo system but I doubt there is condensation on the inside of the intercooler when the turbo is working because the air is probably too warm to reach the saturation point. (just guessing at this) Maybe water can condensate when cruising on highway with the right combination of outside temperature and humidity, but I would not be concerned about that. I would be more concerned about rain water (mist hanging over the road) getting into the turbo inlet and ruining the compressor blades and possibly collecting in the intercooler. If that happened then I could just imagine a puddle of water suddenly being pushed into the engine at full throttle. The design of the air intake and ability to shed and reject water droplets is extremely important.

 

I'm still not buying it. All one has to do is take the air from somewhere other than the engine compartment which is what most, if not all, vehicles have been doing for some time. Besides, the temperature difference between engine compartment air and outside air isn't going to be enough to allow a cooler to be used in the manner you are suggesting.

 

Lady.. I think the air has been condensed by the turbo thus making it way hotter than the ambient air. Going through the intercooler would then cool it down substantially before entering the engine. At least that is the way I understood it. Good posts here!

 

By condensed, I'm assuming you mean compressed. You are correct about compressed air exiting the turbo is much hotter but that's not what I'm referring to. I'm referring to 03 SVT VERT'sassertion of air being sent through the intercooler BEFORE being compressed and pointing out how his arguments don't hold water.

 

Maybe you guys didn't read this one ....

strictly speaking...
intercoolers go between stages
aftercoolers go after all compressor stages

ecoboost uses an air-air aftercooler. but i susupect at some point they may change this to an air-water aftercooler to mitigate the condensation problems they are having in humid environments. (remember what i said about the real world vs. 300hr dyno flogs?)

never heard of a precooler, but i suppose they are out there in some isolated applications.

 

I think we're misreading, or misunderstanding some of what is being written.

The air going thru the engine may start from inside the engine bay as with an old fashioned air cleaner sitting on top of a carburator, or may have an intake in the front of the engine by the radiator as in some more modern engines. From whatever source it starts from, it goes thru the air filter, thru the compressor, which also heats the air.

Then it passes thru the OUTSIDE of the intecooler, which may be internally cooled by another air source or some type of cooling liquid. This cools the air back down just prior to it entering the engine.

Do we agree with this?

If so, then driving in a rainstorm in an F150 EB, and injesting rain water into the big hole where the license plate should be, might allow water to go "inside" the intercooler, but that air flows out of the intercooler, and in no way could this air or water end up in the combustion chamber. The only way this could happen is from condensation from the outside of the intercooler. This is the problem addressed in another thread.

 

Hot air throughs through the intercooler (technically an aftercooler as described above) the same way how coolant flows through a radiator.

cool air passes over the intercooler and removes some heat from the compressed air flowing through it.

the condensation issue is a byproduct of hot, compressed air being turned into cool compressed air. hot air will hold more moisture than cool air. it is the same condensation you get inside your air tank, only there is no drain.

 

The factory intercooler on the 03-up Supercharged Cobra engines is under the supercharger and the compressed air blows thru the intercooler before entering the intake ports. They use a air-to-water type unit, where as the Eco-boost F150 uses an air-to-air unit. The Mustang uses the water-to-air type mostly due to the limited space available for and adequate air-to-air unit.

Together



Apart

 

see changes above. This is the way I understand the system to work.