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I stole this off the internet so it must be true
What Does an Air Intake Resonator Do?
The Common Misconception
Most hot-rodders and car enthusiasts think of intake resonators as simple mufflers in the intake tube, devices designed to siphon all the awesomeness out of a car's sound track to appease soccer moms and senior citizens. That makes it a prime candidate for the "chuck-it" school of auto modification. After all, it's basically just a plastic tumor growing off of a tube that should by definition be as smooth and blemish free as possible. While sound control is indeed part of the resonator's job, the sound control itself is really more of a side effect of its primary purpose.
Pressure Wave Harmonics
Air flowing into your cylinder head's intake port doesn't move in a straight line while the valve is open, then politely stop in its tracks to await another valve opening. When the valve closes, the moving column of air slams into it, then compresses and bounces back like a spring. This pressure wave travels backward at the speed of sound until the intake runner opens up or it hits something, and then it bounces back toward the cylinder. This is the "first harmonic." The pressure wave actually bounces back and forth two or three more times before the intake valve opens again.
Intake Tube Pulses
The resonator in your intake is technically known as a Helmholz resonator, an acoustic device used to control pressure wave harmonics. Air bouncing back out of your engine and into the intake tube doesn't do it in a single pulse the way it would in a single intake runner; the multiple pistons put out pressure waves at their own intervals, and some of those are going to try to bounce back in while others are going out. The result is a "clog" or high pressure area in your intake tube that ultimately limits airflow through almost the entire rpm spectrum.
The Resonator
Adding an expansion chamber to the intake tube forces air coming back out of the engine to slow down to fill the cavity, thus expending a great deal of its energy and slowing the pressure wave reversion. This slowdown allows fresh air to flow toward the engine without fighting pressure reversion waves the entire way, thus aiding in cylinder filling. Since these pressure waves are essentially sound, giving them a place to expend their energy before exiting the air filter box ends up dampening the intake noise and quieting the engine. Thus, the resonator helps to make the engine paradoxically quieter and more powerful.
Well whats referred in this video is, that people are REMOVING resonator box and replacing it with a straight pipe? That REDUCES the space in the airbox. In this "mod", we are not reducing the space but quite the opposite increasing it.
And lets not forget that guy in the video is talking about 4-stroke engine, on modern 2-stroke engines we have REEDS that stop airflow back to the intake. I can also link some videos if you want to learn more about differences on 4-stroke and 2-stroke engines?
And after all dyno results speaks itself and also race sleds like I mentioned in my earlier post.
Whats funny to me, lots of people even this forum are installing aftermarket cans which you can see in the dyno with -5hp loss on the average. Theres no aftermarket can that increases your engine hp by itself by adding it to a stock sled. Imagine paying 300-600$ for rubbish quality part, losing horsepower, making your sled louder so trails and riding areas to be shut down haha.
, we are snowmobilers)
