Intercoolers

[mfmark5007]

If intercoolers compact more air into a square inch....isn't it logical for PSI to increase throught the intercooler?

Because cold air is more dense....thus more compressed...right?

[turbo2nr]

sounds correct to me... but the i\c helps free up psi.. with a intercooler you can boost more..


1

[PWMAN]

Well, an I/C cools the air, but when it passes through the fins there is actually a pressure drop because it slows the air down. So I'm not sure about it creating more pressure, all I know is that it comes out the other end of the I/C less pressurized. So the answer to your question is no, but I'm not sure why.

[mfmark5007]

Well if it slowed down...wouldn't preasure build up...causing a psi increase?

[PWMAN]

Originally Posted by mfmark5007

Well if it slowed down...wouldn't preasure build up...causing a psi increase?

Now this I can answer with an example - Think of a tire on your car. If you put more weight in your car it doesn't change the pressure of the tire. Again I'm not sure why, I just know it doesn't.

[GundamExpo]

The point of the turbo isnt to add compression, its just to put more air into the engine, so it really dosent matter.

Your tire example wouldent work. When you put more weight in the car, the air goes to the top of the tire. Unless your intercooler bulges out, this example wouldent work.

I would have to think that the compression would lower, because cold air takes up less space, but then the turbo would continue to pump in more air to keep the pressure uniform, so it probably stays the same... My head hurts...

[ShwedishFish]

im not too sure on the specifics of intercoolers but...

there is no pressure change in an ideal cooler, as temperature decreases the density will increase, this is good, the more O2 molecules that go in the engine the more fuel you can burn

the idea of turbos and all that is to increase the density of air, dont get hung up on the idea of pressure

[PWMAN]

Originally Posted by ShwedishFish

the idea of turbos and all that is to increase the density of air, dont get hung up on the idea of pressure

Take the complete opposite of what you said and thats the right answer. The purpose of an intercooler is to increase density of the air.
Purpose of a turbo is to put more pressurized air into the engine, hence the PSI rating on a turbo car. Like I am running 9 PSI in my Daytona, that is pressure not density.

[Polygon]

LOL, PWMAN beat me to it.

A turbo is specifically meant to force more pressure into each cylinder raising the compression. That is why you can't add a turbo to a high compression engine without changing the compression first.

Anyhow, the deal with an intercooler is that they are big and they have to be filled with air. You can expect about 1.5 PSI at the most. Any intercooler that allows for more of a pressure drop isn't worth your money. It all depends on how they are designed. The reason the intercooler allows you to run more boost is because it cools the intake charge. If you didn't you would get detonation. It is not that it "frees" up more boost. It is that it cools the air enough to keep it from causing detonation. Also, colder air means more power, it is also improves responsiveness and will allow the turbo to fill the cylinders quicker.

[ShwedishFish]

i dont see how thats the opposite of what i said, its the same thing

you repeated what i said about intercoolers increasing density

a pressure increase from a turbo, is also a density increase (assuming constant temperature),you want more molecules of oxygen to burn more fuel, higher density is key

you can talk all you want about pressure ratings but that doesnt accurately desrcibe the situation. there can be an infite amounts of different densitys at a given pressure, depending upon temperature

i was just trying to explain the basic thermodynamics, but i guess im getting to scientific

[PWMAN]

Originally Posted by ShwedishFish

a pressure increase from a turbo, is also a density increase (assuming constant temperature),you want more molecules of oxygen to burn more fuel, higher density is key

No it isn't. Density stays the same. A turbo forces more air (of the same density) into the engine. When you add more fuel to compensate for more air you get more power. The intercooler is the only thing that changes the density. That is why you have to have lower compression in a turbo car, because the compressed air actually causes less density and higher temperatures. That is also why when you add an intercooler you can run more boost, because it gives the incoming air more density.
Yes higher density is important, thats why there is such thing as an intercooler! The turbo itself does not change the density.

[ShwedishFish]

honestly i dont know that much about turbos, but i do know thermo, and thats basically what were talking about, so maybe im wrong, but hear me out

inside a cylinder just before ignition there is a fixed volume. you say a turbo put its "more" air in, i assume you mean the turbo is pushing a higher volume of air in? but this isnt possible because the cylinder can only hold a certain volume of air, turbo or not. the air is at a higher pressure and therefore a higher density in order to burn more fuel, does that make sense?

[PWMAN]

Higher pressure does not mean higher density.

[ShwedishFish]

i know man, i already said that

[PWMAN]

Originally Posted by ShwedishFish

the air is at a higher pressure and therefore a higher density

Than what is that?