Originally posted by Bell Intercoolers FAQ:
A typical air-to-air intercooler for a street application achieves between 60% and 70% efficiency, an excellent/optimum design for road racing can approach close to 90% efficiency, but requires an adequate "budget!â?
Typically, a liquid-to-air intercooler achieves higher efficiencies than an air-to-air intercooler, starting at 75% efficiency and reaching peaks of 95% efficiency. Another advantage is the optional use of ice as a coolant, which is the only way to reduce the charge-air temperature below the ambient air temperature.
Very cool info. I'm sticking with my water-to-air. 
BP
Ben ---'96 Contour GL * Zetec ATX * Tan on Black steelies---
+++JRSC M62 Under Construction+++
My big-a$$ mod list. 
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