2800 rev/minute divided by 60 seconds/minute = 46.66 rev/second
46.66 rev/second X 360 degrees/rev = 16,800 degrees/second
452 degrees / 16,800 per second = .0268 seconds.
This .0268 seconds is the critical time factor. During this .0268 seconds that the intake valve is closed, the pressure wave is moving at 1,125 feet/second and travels 30.15 feet.
At resonant conditions, the pressure wave has to travel 30.15 feet to arrive at the intake valve when it is open. Since the pressure wave spends this time going up the runner AND going back down the runner, the runner length is actually only half of 30.15 feet, or 15.075 feet, which is equal to 181 inches.
Swell. Terrific. 181 inches. How does a 30" ram tube work if our equations say we need 181"?
The answer is: 6
Start the clock the first time the valve slams shut and the pressure wave is formed.
The wave bounces away from the valve and reaches the end of the 30" tube. Time now: .00223 seconds.
The wave bounces back down the 30" tube and hits the closed intake valve. Time now: .00446 seconds.
The wave bounces off the valve and repeats the trip every .00446 seconds.
At the critical time of .0268 seconds, our wave traveled the target distance of 181" up and down the tube. Although our pressure wave arrived at the intake valve five times to find it was still shut, on the 6th bounce our wave arrived to find the valve open.
The pressure wave entered the cylinder and we had ram induction!
Ma Snart
