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Originally Posted by sb

Here's an example on data I ran for someone with a 540, AFR heads, 5600-5800 peak rpm:

Quote:
Pipemax:
To measure port length, measure top of port(Roof) and measure bottom(Floor) of port. Add together. Then divide by 2.

{use Scotch 3M 218 Fine Line Tape to measure Roof and Floor Lengths}

- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 36.977" (usually this Length is never used)
2nd Harmonic= 20.987" (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 14.652" (ProStock or Comp SheetMetal Intake)
4th Harmonic= 11.532" (Single-plane Intakes , less Torque)
5th Harmonic= 9.357" (Torque is reduced, even though Tuned Length)
6th Harmonic= 7.872" (Torque is reduced, even though Tuned Length)
7th Harmonic= 6.794" (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 5.975" (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

Plenum Runner Minimum Recommended Entry Area = 3.194 to 3.593 Sq.Inch
Plenum Runner Average Recommended Entry Area = 3.672 Sq.Inch
Plenum Runner Maximum Recommended Entry Area = 3.751 to 4.439 Sq.Inch

Minimum Plenum Volume CC = 1157.9 [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 70.7 [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 8861.2 [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 540.7 [typically for Tunnel Ram Intakes]

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-- Cross-Sectional Areas at various Intake Port Velocities (@ 28 in.) ---
159 FPS at Intake Valve Curtain Area= 4.524 sq.in. at .640 Lift
181 FPS at Intake Valve OD Area and at Convergence Lift = .563
223 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 3.221 sq.in. at 5600 RPM
350 FPS Velocity CSA= 2.051 sq.in. at 5600 RPM Port Sonic-Choke with HP Loss
330 FPS Velocity CSA= 2.178 sq.in. at 5600 RPM Port Sonic-Choke with HP Loss
311 FPS Velocity CSA= 2.311 sq.in. at 5600 RPM Smallest Useable Port CSA
300 FPS Velocity CSA= 2.395 sq.in. at 5600 RPM Recommended Smallest Port CSA
285 FPS Velocity CSA= 2.521 sq.in. at 5600 RPM Recommended Smallest Port CSA
260 FPS Velocity CSA= 2.764 sq.in. at 5600 RPM Recommended Port CSA
250 FPS Velocity CSA= 2.874 sq.in. at 5600 RPM Recommended Port CSA
240 FPS Velocity CSA= 2.994 sq.in. at 5600 RPM Largest Intake Port Entry CSA
220 FPS Velocity CSA= 3.266 sq.in. at 5600 RPM Largest Intake Port Entry CSA
210 FPS Velocity CSA= 3.422 sq.in. at 5600 RPM Torque Loss + Reversion
200 FPS Velocity CSA= 3.593 sq.in. at 5600 RPM Torque Loss + Reversion

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