Engine temp vs. hp?

[Paul Workman]

The trouble with "rules of thumb" is that often the rule is remembered, but not the attending circumstances forming the basis of the "rule".

For example: The rule of thumb is that "oil will float on water". But, the underlying circumstances are the oil and water are relatively pure AND in the presence of gravity...(You see where I'm going, doancha?): Change the circumstances - i.e. add detergent to the mix in a zero gravity environment - and the rule that oil rises to the surface...is wrong!

So, hopefully the example above opens our minds enough to ponder this: If knock/detonation is not present at say 205 degrees F at WOT, are we sure a motor will really put out more hp if temperature is reduce to say 170 degrees? If so why?

I'm dubious of the argument that air density entering the engine is the entire answer: A 350 ci 4-stroke motor at 7000 rpm (efficiency factor included) will pull approx 10 cubic feet of air/second. I don't see how there is going to be any significant transfer of engine heat to the rush of incoming air - to reduce the air density by any significant amount**. I'm not a mechanical engineer - I just have a physics background (and you know what they say about having just a little knowledge and being dangerous!).

**The operative phrase. What is or is not "significant" might be in the eye of the beholder, I suppose.

Just food for thought. (Hey! Gimme a break! There's feet of snow on the ground, and I can't go out for a ride and it's killin me!)

P.