Quote:
Originally Posted by Doc Joe
I had a 2001 7.3 diesel and if it was raining or better yet missing, my truck would run like it had two turbo's. It was amazing, I did notice on my wife's Colorado, it runs better when it is raining or misting. I think it is because of the added water grains in each intake stroke.
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In a Diesel, which already runs pretty much leaner than a gasser, the higher humidity does increase the air density since it requires a higher air mass to reach the latent heat of evaporation and increasing the internal pressure on the combustion chambers (even though it won't harm the engine itself because the evaporated water content stores the extra thermal energy during the compression stroke and releases it more effectively in a more homogeneous way across the combustion chambers due to the high thermal conductibility of water), thus leading to a more accurate combustion of the fuel. Meanwhile in the gassers, it does allow a leaner AFR without the risk of melting a piston.