Quote:

Originally Posted by **blueovalz** Thanks for sharing that with us Andrew. Have you already posted the results of your program on header tube length. If not, I'm sure they would also be of interest.
Terry |

Hi Terry,

here is the header recommendation for engine from the Pipemax program:

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--- Single Primary Pipe Specs --- for 433.893 CID from 4300 to 6800 RPM

Diameter= 1.807 to 1.932 Length= 31.8 to 34.6 inches long

--- 2-Step Primary Pipe Specs ---

1st Dia. inches= 1.807 Length= 15.9 to 17.3

2nd Dia. inches= 1.932 Length= 15.9 to 17.3

--- 3-Step Primary Pipe Specs ---

1st Dia. inches= 1.807 Length= 15.9 to 17.3

2nd Dia. inches= 1.932 Length= 7.9 to 8.6

3rd Dia. inches= 2.057 Length= 7.9 to 8.6

--- Header Collector Specs (Conventional Straight Tube) ---

Diameter= 3.309 to 3.559 Tuned Lengths= 17.9 best and also 9.0 or 35.8

--- Header Collector Specs (Megaphone or Diffuser Cone Shape) ---

Diameter= 2.809 taper to 3.809 Megaphone/Diffuser Length= 17.9 inches

Best HP/TQ Tuned Collector Lengths= 17.9 , 35.8 , 71.6 , 143.3 inches long

Worst HP/TQ Loss Collector Lengths= 26.9 , 53.7 , 107.5 , 214.9 inches long

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

---- Primary Pipe's Harmonics ----

1st Harmonic = 138.8 inches long ... typically never used

2nd Harmonic = 52.9 inches long ... longest recommended

3rd Harmonic = 31.8 inches long ... highly recommended , best Torque Curve

4th Harmonic = 22.2 inches long ... shortest recommended

5th Harmonic = 16.8 inches long ... typically never used

6th Harmonic = 13.3 inches long ... typically never used

7th Harmonic = 10.9 inches long ... typically never used

8th Harmonic = 9.0 inches long ... typically never used

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----

1st Harmonic = 143.3 inches long ... longest with Mufflers and TailPipes

2nd Harmonic = 71.6 inches long ... longest recommended with Mufflers

3rd Harmonic = 35.8 inches long ... more bottom-end Torque

4th Harmonic = 17.9 inches long ... highly recommended , best Torque Curve

5th Harmonic = 9.0 inches long ... reduced Torque , more top-end HP sometimes

6th Harmonic = 4.5 inches long ... reduced Torque , not recommended

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based on this I built a non-stepped design with 32 inch primaries in 1 7/8 inch, and an 18 inch collector into a chambered muffler which I treated as the end point in the system because of it's volume.

Cheers, Andrew