# Pressure wave tuning

USMC8541

## Main Question or Discussion Point

I need some help.

I would like to design a custom intake for a 8 cylinder IC engine.

some back ground information.

All cylinders are fed by a length of pipe with a tapering crossectional area (intake port). All 8 intake ports are connected to a common plenum.

What I am trying to accomplish is to tune the pressure wave in the intake port to arrive at the intake valve at a pre determined moment. The reasoning is if the + pressure wave arrives at the valve just before the valve closes the momentum of the air will continue to flow into the cylinder aiding in volumetric efficiency.

I am having a rough time developling an equation or method using crossectional area, varing crossectional areas, pipe length, and plenum volume to accurately predict the frequency of the + positive pressure wave.

If I haven't given enough background information let me know or ask me what you need to know and I can go more indepth.

Todd

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krab
I am having a rough time developling an equation or method using crossectional area, varing crossectional areas, pipe length, and plenum volume to accurately predict the frequency of the + positive pressure wave.
Many people have had a hard time developing such a formula. Most often, ram tuning is done experimentally with a good machine shop and a dyno.

The formulas that do exist can be found in a book like "Internal Combustion Engine in Theory and Practice: (2 volumes) by Charles Fayette Taylor. Look for it at Amazon or other bookseller.

USMC8541

I have about 15 ICE books. But if you notice they copy someone elses work majority are repeats of each other with slightly different spins on them. The formulas in the books are for four cylinders only. They don't tell you that in the books. I had to do some research to find out what size engine it was for.

I know you could do it with a dyno and flowbenches and so on but it would be alot easier, cheaper and faster if I a had reasonable starting point.

Todd

krab