Posted for Walter Atkinson <walter@advancedpilot.com>:

 Scott:
 
 I agree with all of those premises.   I also think it wise to consider the
effect that the high IAT has on non-intercooled systems.  I'm concerned about
that effect as it is significant in narrowing the detonation margin.  A 100dF
rise is not an insignificant rise in IAT in that regard.  I think you might
find that any reduction in IAT from fuel vaporization at the cylinder
induction port will be insignificant.
 
 Walter
 
 
"""
 I measured lower cowl air (in my airplane only) at its hottest place
accumulating all of the heat created, not at the cooler front engine area
where the filter draws its air and I found that, generally, the air entering
the induction system was at its worst about 100F above the ambient.
  
 I measured the air exiting from the heat muff, a source of carb heat air, and
found it hotter and sometimes un-measurable with the temp probe display I had
available because it was limited to 99C (210F).
  
 Carb air temp probes are useful in that they measure the temperature of the
Fuel/Air mixture and, as such, point out that the combustible mixture is cool
enough even after HOT carb heat air is added.
  
 It seems that filtered under cowl air would be usable in an injected
environment after raising the initial induction air by 100F, passing it thru
the oil sump (just like many carb engines) and finally cooling it down by the
F/A atomization at the cylinder head.
  
 If used early in the takeoff phase, the engine will suffer a power loss on
the order of 5% to 10% because of the rise in temp (not the
total temperature of the air).   This is significant in a commercially built
under powered airplane...  It is less significant in something like a Glasair
or Lancair because there is an abundance of power available.  Of course,
rational pilots using such a system would understand that performance is
negatively affected and could choose to use the ram air in questionable
circumstances.
"""