Ram pressure formula3/7/2023 If these parameters are not balanced properly, ram induction doesn't work. The number of crank rotation degrees the intake valve is closed.The following parameters affect the arrival of our pressure wave at the intake valve: Now let's look at the limitations of ram induction. The example above has demonstrated why ram induction works. This chart demonstrates the effect of ram induction using long rams: The pressure wave entered the cylinder and we had ram induction! On the 6 th bounce our wave arrived to find the valve open. Although our pressure wave arrived at the intake valve five times to find it was still shut, 0268 seconds, our wave traveled the target distance of 181" up and down the tube. The wave bounces off the valve and repeats the trip every. The wave bounces back down the 30" tube and hits the closed intake valve. The wave bounces away from the valve and reaches the end of the 30" tube. Start the clock the first time the valve slams shut and the pressure wave is formed. How does a 30" ram tube work if our equations say we need 181"? 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. 0268 seconds that the intake valve is closed, the pressure wave is moving at 1,125 feet/second and travels 30.15 feet.Īt resonant conditions, the pressure wave has to travel 30.15 feet to arrive at the intake valve when it is open. 0268 seconds is the critical time factor. The engine rotates twice (720 0) for the intake to open once.ħ20 0 minus 268 0 = 452 0 of crank rotation that the intake is closed.Īt 2,800 RPM, 452 0 =. A good estimate for the speed of sound is 1,125 feet per second.įor the F & G camshaft, the intake valve is open for 268 0 of crank rotation. Our pressure wave travels at the speed of sound. Let's look at some numbers to see how the 30" long ram tubes were developed. This combination of synchronized events is known as 'resonant conditions'. In order to create this supercharging, all of the variables have to be aligned so the pressure wave arrives at the intake valve at the right time. This bouncing pressure wave of air and the proper arrival time at the intake valve creates a form of supercharging. This pressure wave bounces back and forth in the runner and if it arrives back at the intake valve when the valve opens, it is drawn into the engine. This compressed air has to go somewhere so it turns around and flows back through the intake manifold runner in the form of a pressure wave. With one piece of air piling up on the next piece of air on the next on the next, the air becomes compressed. But the air can't go anywhere because the valve is shut so it piles up against the valve like a chain reaction accident on the freeway. Here is where the law of inertia comes to play - because the air was in motion, it wants to stay in motion. Everything is fine and dandy until the intake valve shuts. Visualize the intake cycle of the engine as air flowing through the intake manifold runner, past the intake valve, and into the cylinder. This law is the foundation for Ram Induction. More commonly known as the "law of inertia", the first law of motion is:Īn object in motion tends to stay in motion. In addition to discovering the best use for the fig, Sir Isaac Newton created three "law's of motion".
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