[rbattelle]

Cold air intake systems claim to increase engine power by increasing charge air density, thereby increasing the amount of oxygen available for combustion.

However, referring to Taylor's book "The Internal Combustion Engine in Theory and Practice", volume 2, page 105, we find that delay angle and rate of pressure rise both decrease with increasing inlet temperature. This would seem to indicate that supplying the engine with warmer air would increase efficiency and durability.

Obviously, the merits of increasing charge air density cannot be ignored. But is more to be gained from using colder, denser charge air (and hence increasing delay angle and rate of pressure rise) than from warmer, less-dense air?

Or perhaps the increase in temperature decreases compressor efficiency, causing inlet pressure to drop, which would cause an increase in delay angle and rate of pressure rise thereby counteracting any benefit of warmer intake air?

Perhaps we should all eliminate the intercooler, which would increase charge air temperature without affecting the compressor?

Any thoughts on this mess would be appreciated! Maybe I've missed something?