To cold is the point at which icing occurs in the venturi area,and that's virtually unlimited in a modern fuel injected application probably aroud -20 degrees F.On older carburated designs a hot spot had to be added for cold weather usage because ice could form at tempertures above freezing.

 

Ahh, very good point. -20F would be nice though wouldn't it.

 

i've found that much below around 40ºF there isn't much gain to be had in lower temps. at temps lower than that the fuel doesn't atomize as well in the intake as it would just before it shoots into the head. if these engines had a direct injection fuel system there would be some more gain in that. once you get to around 20ºF or so you end up with commonly very low humidity in the air as well as if i recall correctly a lower % of oxygen in the air.

 

Why would there be a lower percent of O2? Percent by volume? How? It's denser.

 

where does the engine measure temperature of air coming in so as to adjust air/fuel mixture accordingly? if it is at the maf, then wouldnt you have to make the air cold BEFORE the maf?

 

The IAT sensor is incorporated into the MAF. Except for the Radix kit where its relocated to the intake manifold. And yes it would need to be cooled before the MAF.

 

i could be incorrect on that, but i'm trying to remember from my chemistry class where this discussion came up. it may be that there is less of that process going on of plants creating the oxygen in the cold. i honestly don't remember. i could be w***g on that one.

 

 

I would be confused too. I have a chemical engr book right here that explains everything very nicely though once you decipher through the bs. I had to use it my junior year.

 

Seriously, I don't care about plants. I care about my engine and the air it breaths!