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I only read the first post in the link provided and it sounds like he didn't tune. I have not done any tuning, but based on what I've been reading here and elsewhere, you MUST find a way (reflash, piggy-back, etc) to tune the car for any of the breathing mods to be effective. I believe it WILL make a difference (albiet, a small one) for NA IF you tune it.
 

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I think a good way to settle this isn't with dyno runs, but with air flow rates. I don't know what they are called, but there is a machine that you can hook an intake ONLY up to (ie: remove it from the engine and place it in/on the machine) and it will give you cfm's (cubic feet per minute) through the intake manifold. It would be interesting to see the flow rates between a stock plenum, the Kinetix SSV, and some other popular 3rd party plenum. I was lucky enough to tour a custom shop near Minneapolis that is known for tuning and customizing Corvette engines, and they had one of these flow machines. It was pretty interesting how they used it to tweak their intake designs.
 

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Inlet pressures and temps may vary over the long term (minutes, even seconds), but this variation is going to be miniscule. Baring anything catastrophic, we will not be experiencing dramatic atmopheric pressure and tempurature changes. Our intake air flow does not move through or across a greatly varying change in tempurature. In the short term, crankshaft revolution to revolution, intake pressure and tempurature changes will be nill. I would have to conclude, that for this application, concerns about inlet pressures and temps changes are withou merit.

The abdiatic process is definately present. For those unfamiliar, the abdiatic process is one where is one where the system neither gains, nor losses heat as work is done. There IS heat gain and loss as as the engine goes through it combustion procces. Once the engine reaches operating tempurature thr combustion process and cooling systems allow the engine to reach and an equilibrium tempurature, i.e nornal operating tempurature. This results in a constant tempurature in and around the plenum. As a result of this, the ideal gas equation (P= nRT/V) applies without tempurature becoming a consideration. Temperature is constant, so as Volume increases, Pressure drops and the moles of air spread out to fill the increased volume.
I would disagree with most of this. Temperature will not be constant. The temp difference between the incoming air the the temp of the plenum will be drastically different -- by as much as 50 deg C. I would argue that this alone could cause issues with the ideal gas law. Admittedly, I'm speculating and have no real data to back that up.
 
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