Quote:
Originally Posted by vector1
here is an example of tuned length runners from a pipemax program just to give an idea of the differences in runner lengths used. this is off a 9.5 deck windsor with mild solid roller cam and afr205's. the plenum would fit on top of the runners.
- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 32.201 (usually this Length is never used)
2nd Harmonic= 18.276 (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 12.759 (ProStock or Comp SheetMetal Intake)
4th Harmonic= 10.042 (Single-plane Intakes , less Torque)
5th Harmonic= 8.148 (Torque is reduced, even though Tuned Length)
6th Harmonic= 6.855 (Torque is reduced, even though Tuned Length)
7th Harmonic= 5.916 (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 5.204 (Torque is greatly reduced, even though Tuned Length)
Note> 2nd and 3rd Harmonics typically create the most Peak Torque
4th Harmonic is used to package Induction System underneath Hood
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All of those numbres are for a specific rpm, not listed.
Whenever you calculate an optimal runner length, you need to pick a rpm where you want the maximum increase in power, and calculate runner length based on that particular rpm range. There is a formula, based upon the speed of sound, the speed of the pressure waves.
the early Chyrsler 300 413's had those long cross ram tubes, tuned for 3000 rpm or something like that. Racers, cut the tubes, rewelded them with shorter runner lengths to raise the rpm of the maximum power boost to 5000 rpms or something like that.