[Stan Weiss]

Originally Posted by steve25

Intake air flow in a NA motor goes down the runners in pluses in a on and off fashion.

These pulses will curtail the flow of air once the speed of these pulses reach 55 to 60% of the speed of sound.
This is because it takes energy to restart the air mass once it has stopped.

The speed of sound is stated as being at standard temperature and pressure at sea level.

This all means that as the intake air mass heats up on its way thru the complete intake tract that maximum velocity that it can attain before the cut off point is reached is taking place at a lower rpm.

Now this does not mean that super cold air will make the most power as the air temp and the fuels make up must be enough to turn the fuel into a nice burning vapor along with some fuel mist that will later be turned into a vapor when it’s cramped up at TDC.

Also interestingly enough if your thinking that having all the fuel turn into a vapor would be the way to go you would be wrong!

Excess Fuel vapor takes up room that could air at a certain point and this then makes for a reduction in power output just like having not enough fuel going into a good burnable vapor !

As temperature increases so does the speed of sound. In other words the speed of sounds is slower at 60 degrees then it is at 120 degree.

Stan