attn redmist re: heimoltz

[strap-on]

is the length of the intake runner, measured from where the maifold meets the head, or is it measured from the valve to the end of the trumpet?

oh and can i have the link again

[ChaosAD]

valve-end of trumpet

[RedMist]

Shyte, sorry missed this one. I was on Holiday.

Actually most calculators measure from the valve face.
You may wish to try
http://www.wallaceracing.com/runnertorquecalc.php

For some basic runner length calcs. Please bear in mind other calculators vary in regards to length.
I have another that I made up in a spreadsheet. However I dont have the ability to host it.

[bad20v]

Calculate Optimum Runner Size and Length
To find the optimum intake runner area and length for a particular rpm.

Engine Displacement (cubic inches only) cubic inches : 97

Number of Cylinders : 4

Peak Torque RPM RPM : 5600

Optimum Intake runner area 1.54 square inches (calculated)
Optimum Intake Length 15.00 inches long (from valve head to plenum).

So this tells me that I need to have trumpets made that are 15 inches long?

(97' Trueno BZR w/blacktop 4age 20v)

[RedMist]

Nope, from the valve face. If your engine is assembled I would look at the engine side on and guess the inlet valve position. You should be able to get within 10mm or so. Then measure to the airbox face. Whatever left over from your 15 inches is the trumpet length.
In regards to RPM tuning remember your attempting to lengthen your RPM band by placing the resonance boost at the bottom of your RPM band. Mine is tuned for 5.5k, thats just when the cams come on.

Oh, and remember the other calculators mentioned above.. the all come out longer than the online one.

[bad20v]

Sweet as. Cheers RedMist.

[RedMist]

On reflection, guessing the inlet valve position probably isnt the best solution. If you can find someone with a dissasembled head measure the distance to the valve face. It will make your trumpet length much more accurate.