What is this?

[Bikeman315]

You know if a new member reads this post it will scar them for life.

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[BLUDICE]

I won't BS you - I quit raising car hoods back in the late '90s.

 

[Bikeman315]

I won't BS you - I quit raising car hoods back in the late '90s.

Remember when you raised your hood and the only thing under there besides the engine was a PVC valve?

 

[BLUDICE]

Remember when you raised your hood and the only thing under there besides the engine was a PVC valve?

AND a battery - lol.

 

[Cobra Jet]

That’s the snuffaluffugus...

 

[CVCashmere]

Stang'rs

I apologize for being serious...for the first time in 50+ posts.

Here is a BS explanation of why that bloated box works:

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.


CVCashmere

 

[lew]

Pressure wave Harmonics brings to mind expansion chambers.

I remember back when I was a motocrosser. I was into 2 strokes then. The expansion chambers were designed to allow for optimum flow and also provided area for the exhaust to expand allowing free flow without having to push the exhaust through the pipe. It also provided back pressure during the intake cycle to keep fresh fuel/air mixture from exiting with the exhaust all this accomplished by chamber diameters and length.

 

[EcoVert]

Sounds like the explanation my buddy got when he took his Colorado back to the dealer with transmission problems.

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