An engine can run past 14,7:1 with out detonating, running cooler intake charges will have more air and would be good for more fuel to make more power.not adding fuel would lean it out and cause a drop in performance to save fuel but eventually may cause damage dueto higher cylinder operating temps.im not sure if they would really want that or if they would add components to control that such effect.single or twin turbos I wouldn't think would affect charge temps, the efficientcy of the single or dual charge air coolers is what would ultamately affect the air charge temps.
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