> -----Original Message-----
> I have a question about the effective gains from a cold-air intake. I'm
> asking because I read over and over about how much the gains are for a few
> degrees difference (as the cooling of the air is passive rather than
> actively cooled). I've always wondered about this because I live in MN. In
> the next 3-4 weeks, I will likely be starting my truck in the morning
> during temps of -20F. If cold-air intake means more horsepower, shouldn't
> pulling in air that's 100F cooler than summer air make a difference? I
> guess the fact that I don't really notice a "January boost" is making me
> wonder if cold-air intake is just another example of automotive snake oil.
>
> --
> J Wynia
------------------------
Cooler intake air will make more horsepower, as well as better fuel mileage.
That's why every auto manufacturer uses some sort of intake system that
pulls in air from a location away from the highest heat source in the engine
compartment. Cooler air creates more efficient combustion. However, there
are limits to the effect cooler or hotter air will have. Below or above
certain levels, there will be no noticeable difference. The PCM has limits
on how far it will adjust to weather extremes. In a nutshell though,
cooler air is better than hot air. In the 11 years I've been racing my
truck, I've many times compared my factory 10x2.5 enclosed air cleaner with
hoses to the grille area, to an open element, 14x3 K&N filter. The open
element, sucking in engine heat, has always proven to slow me down by a
tenth of a second and 1 mph at the track. That's equivalent to about a car
length in the quarter mile.
Actually, humidity and barometric pressure have a greater effect on
performance than temperature alone. It just so happens that cooler weather
is usually accompanied by lower humidity and higher pressure, thereby
resulting in a noticeable performance increase.
RayB
http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
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