I looked for that "Beehive" thing in the tube but it wasn't there. I think someone posted that they are only on the earlier '05's.

 

Wider diameter tube = increase air flow rate

Basic thermodynamics my friend

I will just jot down the basic equation since you seem to have some engineering background:

mass flow rate = density * velocity * flow area
*Assume density of air is the same since source is the same
*Assume velocity is either slightly less or constant (automative engineering isnt my field, but I would assume the engine WITH tune would pull air at a relativly similar velocity)
*Only variable change is flow area which is greater in the aftermarket CAI
*Thus mass flow rate of air is greater than stock airbox

 

Actually, as I've posted several times before, if you give that stock tube a squeeze you'll see why it is not big enough! It flexes! As high rpms, with lots of draw, the stock tube actually partially collapses, creating less room right when you need more!
Now give any aftermarket CAI tube a squeeze. Nice and stiff! Plus note how most are straighter than the stock one.
So yes, just a better tube can help!

 

Yes, knowing gas laws are part of my job. For laminar flow the Hagen-Poiseuille equation is used. Keeping everything else constant, doubling the length halves the flow, but doubling the diameter increases the flow x16. My point was that the flow will be determined by a fixed orifice (the 60mm throttle body), not the much larger intake tubing. Possibly another factor is the speeding up and slowing down of the airstream due to variability in the circuit. Remember the old fuel injector stacks that touted "constant velocity?"
Anyhow, all this is just speculation without taking pressure readings. I'm sure the people making these CAIs have sound engineering behind these things?? After all the Turboswirl spacer and the throttle body spacer will get you 80MPG and 900HP right?

 

For the Thermodynamics professors out there...when calculating the mass flow rate you cant just assume density is the same. well, in theory you cant.Most of the aftermarket CAIsclaim to have some kind of heat shield.So theair travelling through the intake tubeSHOULD be cooler=> More dense (more dense is better...see Forced Induction) => More airflow...Just thought Id throw that in there.

PS...anyone got an extra East coast CD for the AVIC D3 that they're willing to sell?

 

You are totally right regarding the pressure readings. But honestly, look at the stock tube and compare it to a C&L tube. Its like night and day in regards to quality. Wouldn't the larger tubing with the fixed throttle body resulting in the air having a greater velocity (kinda like a nozzle) into the engine?

I am a third year engineering student so I am not so sure about everything... you seem to know more!

 

I am skeptical regarding the heat shield effectiveness. The density might be slightly more, but the real difference would be in the tubing diameter. Now if you get a hood scoop and draw that air into the CAI intake area (part shielded) than we would be cookin.

 

theres your biggest mistake,going to stangnet.there more interested in jokes and anything but cars.i won't even go there anymore after a week or so ago.there was a big deal about politics and a few of the modarators even got into it and it went down hill fast.just had mine dynoed at AMP in phoenix on thursday.STEEDA COLD AIR,MAC AXLE BACKS,DIABLO TUNE .did a little tweaking and came in at 292 hp,289 torque.caim most won't work without some sort of tune,except airraids or granatellis.makes a difference.[sm=yeahsmile.gif]

 

Big Dave, your asumptions on flow restriction are valid, but when was the last time you saw a CAI with a stock size MAF. They are typically 85 to 95 mm not 60.

 

I was referring to the throttle body being 60mm. I think this is what the stock ones are right?
I have a 90mm Lightning MAF on mine (with the KB kit). I do not know what the stock one is, but my dyno guy said that it was good for around 500HP and wondered why KB changed it??

As far as heat shielding goes, doesn't the stock airbox come from the fenderwell? I don't think it is exposed to engine heat from the onset. And along the tube, the velocity/surface area would not allow much heat transfer anyhow. That is why air-air intercoolers use a radiator-type of arrangement.

The point that I was making was that I think the power increase was mostly the tune, especially if you are setting for 93 octane gas. You are changing the spark advance and fuel curve---that's where the power increase is coming from.