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Old 20-06-2008, 03:52 PM
masterp2 masterp2 is offline
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Join Date: Nov 2004
Location: Desert SW, Arizona USA
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Part of the answer to this question rests in another question: How much evaporation can I expect from small droplets in the .1 seconds that they exist in the induction tract???

The answer: it depends...it hinges on humidity, charge temp, and one very important aspect...disturbance potential. liquid water must interface with a lot of air to fully evaporate, and entrainment in a moving airstream does nothing to help this process. So most people injecting post CAC, at most, see 10% evaporation...my educated opinion.

Want to evaporate liquid water? It must be injected pre-compressor. Assuming adequately low humidity, you will get close to 100% evap rate because of the air interface and high temps.

Lets face another reality, getting more air in is about getting it moving slower (condensing) through your plumbing. That lowers the "negative boost" that needs to be overcome to transport air. The air pump (turbo) does less work when charge is condensed early in its travels. This allows the compressor to operate more efficiently at overboost rpms, with less off-map consequences of heatup.

Anyway, post-CAC injection is not good for anything, except improving combustion quality (on a dry day), and lowering EGT. On a 50 F day in the NE U.S., there is already lots of water in the air, so the only real gains will be pre-turbo, and then only with overboost use, or real inneficient induction plumbing.
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