oil pan 4

I know you guys have to have some input on this one.
Runner length, harmonic ranges, V.E. and questions.
http://www.thirdgen.org/techbb2/show...hreadid=265228
I posted it there becasue I had to use the graph I made.

Zero_to_69

Not that I'm able to answer this to your requirements, but my first questions would be:

- What RPM range are you tuning for?

- What is the valve timing of the camshaft(IVO, IVC, etc.)?

- What is the exhaust system configuration and dimensions (length and
diameter of tubing)?

Most of this is covered in a book I have read. It will be interesting to see
how well I've understood the text to apply it with my own engine.

1racerdude

On my program,with my set up,once you get over 6" intake length(11-11 1/2" total runner length) and on a Pro Stock program,the power fall's off. A 383 turning 7000RPM's and a set of converted heads that flow in the 330's.Right at 5 1/2" intake runner length seems to be a sweet spot and the Pro program takes this into its figures.This also depends on valve timing.
I don't know the formulas for wave tuning but maybe somebody like Larry Maux could help or Bret,or MG.

Zero_to_69

I wonder what the intake pulse length is for an engine with a 5.7' rod, 3.48" stroke @ 5500 RPM?

My theory is the swept volume is going to be a key factor along with the RPM
which will be part of the equation when figuring intake runner lengths.

From the tunnel rams I've seen on Pro-mod alcohol cars, the runners don't seem
to be much longer than 6". I'm assuming this is one full wavelength at the
mid point of their effective RPM window.

IE: Tune the runner length to get the best average power over the geared
RPM range.

oil pan 4

"On my program,with my set up,once you get over 6" intake length(11-11 1/2" total runner length) and on a Pro Stock program,the power fall's off. A 383 turning 7000RPM's"
If you look at the chart the 10'' and 11'' total lengths are what you want the 4th harmonic range at 7000rpms.
For what ranges I'm tuning for, I don't know yet. I was just throwing some stuff out there. Because I left my options open with the cam, intake design, timing and header design.
RPM, higher is better.

1racerdude

You can't build a 8000RPM engine and expect to drive it on the street.
It will be a trailer queen.

SStrokerAce

Swept volume is not going to be critical in length but more in cross section.

Yeah that's always the idea. Build the motor to work in the RPM range that is used in.

Bret

Zero_to_69

"Swept volume is not going to be critical in length but more in cross section."

Interesting. I would have thought the distance of TDC to BDC would have
something to do with the pressure wave length.

Should we be looking at the valve timing events to figure
wavelengths at a certain RPM based on IVO and IVC?

IE: At 4000 RPM, the tuned runner length may be 6.5 inches. At 5000 RPM,
the wavelength might be 6 inches.

contactpatch

Keep in mind that, a pipe resonant at 5000 RPM is
four feet long. 'Higher harmonics', is BS, trying to
give the impression that 'shorter than resonant'
has some mathematical basis.
.
Note, a 'shorter than resonant' pipe is still useful
and desireable, but it is not resonant.
The 'higher harmonics' are barely detectable.

oil pan 4

The second range and higher have lower pluse %'s.
If your so smart show me how to calucate the change in the speed of sound with increase of density I know how to do it with chang in temp but that dosen't help me.
I have most of the formula but it's wrong, it is missing some thing.
I'll post the math on the intake page as soon as I can microsoft paint it.