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Re: Cold, humid day vs cold, dry day. . . Posted by MJM [Email] (#872) [Profile/Gallery] (more from MJM) on Mon, 18 Dec 2000 10:22:34 In Reply to: Re: Cold, humid day vs cold, dry day. . ., Mathias, Sun, 17 Dec 2000 04:54:13 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I don't know that the humidity alone will do that much for knocking. Besides, didn't Saab put lots of money and effort into designing the trionic (and APC before that) control system to maximize power without knock?
Additional water in the combustion chamber will take energy out of the flame front as the water turns to steam. The result is cooler combustion temperatures and reduced knock.
Highly humid air will hold less fuel, since the bonding sites on the air molecules are already taken up with water droplets. Burning gasoline releases energy, heating water takes energy. Less fuel equals less power, especially on a computer controlled engine.
Same principle with nitrous oxide. The nitrous (N2O) doesn't directly "add" more energy to the combustion process, but it does add more oxygen, which means more fuel can be added, and that gives the power increase. The two nitrogen molecules in each nitrous oxide molecule are just along for the ride.
Free oxygen molecules are the key.
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