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Old 12-12-2009, 01:32 PM   #52
JHowerton@Aquamist
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Join Date: Dec 2009
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I would like to add my experience to the discussion. From what we've experienced, the further away from the TB the better, with the exception of the BOV issue. Here are a few rough calc's and an example.

Using the numbers a couple of posts ago, 40lbs/min and a 2.5" ID pipe for simplicity, the air is roughly at 177mph or 3128 inches per second of travel. This means each inch of air passes the jet in roughly .0003sec. At the molecular level of evaporation, this is quite a long time.

For example, a 24" diameter tire makes about 845 revolutions per mile. With a 75" circumfrence, this means each 1" of tire is in contact with the ground for .0005 seconds. Since the contact patch is about 4" long, this means the 1" of tire is in contact for .002 seconds. This is still ample time for the rubber in the tire to create molecluar bonds with the surface(one a few forces generating grip) and break the bonds. Since certain tires can operate at twice this speed we know that the molecular forces can act very quickly.

Back to the jet placement, the evaporation and cooling of the charge, in general, due to mix and charge temp/velocity, begins almost instantaneously. Looking at the 24" pipe before the TB, my guess would be if you looked at the temperture profile of the air in the inlet track, a good deal of the cooling would occur before the TB. Given more water injected, it is even more important to allow for adequate mixing before any separation or sharp bending of the charge flow occurs.

I ran these on a napkin, so if I missed a decimal place or number, feel free to correct me.
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