Which comes first?

[quote author=killa cam link=topic=138252.msg2988828#msg2988828 date=1236818064]
you fucking retard. i wish i could groan the above post!

this has been beaten to death thousands of times.

the colder the air going into the turbo, the colder it is coming out of the turbo. the colder the air going into the IC, the colder it is coming out of the IC. YES, ITS REALLY THAT FUCKING SIMPLE. why is this so hard to comprehend?

[/quote]

Because of the ideal gas law. PV=nRT

If you take any given volume of air and compress it under a certain pressure, you are going to get the same temperature, no matter where you start temperature wise. So, if you take a cubic foot of air and compress it under 15.6 psi, youre going to get the same resultant air temp no matter if your origionally started out with 60 degree air, or 90 degree air.

There are only 2 arguements I can see for a CAI making more power on a turbo car:
1. The stock airbox is just plain restrictive, and its the increase in volume the car is able to draw in that gains power. I believe this is usually the case for most turbo applications.

A lot of cars, ie WRX for example don't get much gain of after market intakes until you've upgraded the turbo charger. I think this is where most of the gain in our cars comes in as well... the stock intake has what, a 2 inch diameter inlet? It seemed tiny.

The power curve difference comes in due to the length of the inlet. Here's a good article:
http://www.sportcompactcarweb.com/tech/sccp_0902_2006_subaru_wrx_test_bench/index.html

2. By ingesting cooler air, are you are ingesting denser air, and thus more oxygen... When its compressed, you will still have heated it up with the turbo charger, but you now have a higher count of oxygen molecules. Is this enough of a difference to show up on a dyno? I dunno... I am no chemist and not even sure the validity of this theory.

your wrong there buddy... you must be reading out of cobbs physics book. it's really painful arguing with people who clearly have no idea what they are talking about. a bunch of garage engineers and mechanics in this place! i bet you think it's possible for an air\air intercooler to have 95% efficiency with only a .5psi pressure drop too.

seriously dude, think about what you are saying there. or, consult a professor or something. i got a nifty experiment... why don't you ask a guy in canada with a DH to log his boost, IATs and BATs, and then ask the same from a guy in texas. compare the results.

or, type "pv nrt calculator" into google, and start playing around with the calculator and see what kind of numbers you come up with. don't forget the n variable either! thats an important one. also look up the definition of an ideal gas, (and learn why 'air' is not one).

sounds like you have a lot of homework! i could simply tell you why you are wrong, but i think you would learn more if you did the research for yourself. sorry to be such a dick about it, but it really gets annoying after a while.

i wish other people would say something too, (isn't tvissues a turbo expert?) but they probably know better than to start up this kind of conversation. god knows this forum is full of experts!

nah dude you came in here saying that shit like it's fact. if you think about it, for only a second, you would realize that the argument is nothing but horse shit. does your car run stronger on cool days vs hot summer days? well according to your post it wouldn't matter, because the turbo heats it up to the same temp no matter what. Wrong!

[quote author=Steve0 link=topic=138252.msg2989418#msg2989418 date=1236832272]
If you wanna play with "n" variable, then you have the 2nd "argument" I gave. Hot air is less dense, and thus you are pulling in less oxygen, you're obviously going to make less power. I also said I was no chemist and was not sure the validity of the answer. [1] How much less dense is 90 degree air than 80 degree air? [2] How much less power are you gonna make? [3] Enough to matter? I have no idea.

I also stand by my claims that part of the gain on many cars from intake systems is from the volume of air being ingested. There are many high horsepower turbo cars out there with an open element right next to the motor.
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to answer your questions, you first have to take into account absolute pressure and humidity. both of those will affect air density. if you were to assume 29.92 inches of mercury and 50% relative humidity, [1] the density of 90° air would be 1.145 kg/m^3 and 80° air would be 1.17kg/m^3, a 2.14% change. lets assume mazda strapped the MZR DISI to an engine dyno, and dynoed the car using the standard reference conditions (22.235"hg, 0% RH, and 77°F)(as per SAE J1349) and came up with 263 peak horsepower. if the temp in the air went up to 90° leaving other variables unchanged, [2] you can expect a drop of almost 4 horsepower. but also consider your pressure and humidity... those have an impact as well. So does it matter? [3] I would say yes. Dread would say no. who's to say either of us are right? make up your own mind on that one. I prefer the best solution, some prefer the easiest solution. cp-e now caters to both types

and of course, a lot of the gain in power comes from REMOVING THE RESTRICTIONS. anytime you reduce the amount of power needed to move air through the cylinders (pumping losses), you will have more power available to spin the tires. the same theory applies to the exhaust side of the motor. this is probably the bulk of the HP gain, but definitely not the only variable in the equation of making power.