[tasdrouille]

The FE impact of the forward facing CAI does not come from lower IAT, but from the added intake pressure vs stock, or reduction of the pressure drop in the intake if you prefer.

BTW there is sound proven facts behind the WAI

Here's what I found out when I was doing my homeworks before going ahead with the WAI.

WAI arguments

- Pre-heated intake mixture at low rotational speed improves combustion. (Chiu and Horng, 1992)
- Specific fuel consumption varies inversely proportional to the square root of the suction air temperature (Nakajima et al. 1969).
- Higher ambient temperature is found to increase the flame speed, the combustion reaction rate, the uniformity of the fuel-air mixture and reduce the heat transfer rate though the cylinder walls (Pulkrabek, 1997).
- For lower temperatures, only a small part of the injected fuel is vaporized, causing nonhomogeneity. As a result, lower flame speeds, higher unburned mixture, higher hydrocarbons and carbon monoxide emissions, and loss of power are observed (Pulkrabek, 1997; Heywood, 1988).

References:
Chiu, C.P., and Horng, R.F., 1992, “Effects of Intake Air Temperature and
Residual Gas Concentration on Cycle-to-Cycle Combustion Variation in a
Two-Stroke Cycle S.I. Engine Equipped with an Air – Assisted Fuel Injection
System”, JSME International Journal, Vol. 37, N.4, pp. 957-965.

Nakajima, K., Shinoda, K., and Onoda, K., 1969, “Experiments on Effects
of Atmospheric Conditions on the Performance of an Automotive Gasoline
Engine”, SAE Transactions, SAE 690166, pp. 745-766.

Pulkrabek, W.W., 1997, “Engineering Fundamentals of the Internal
Combustion Engine”, Prentice Hall, Inc.