Every engine depending on compression, cam and desired rpm point will want a different length ram tube.
Using pipemax for my OHC Pontiac six with my cam and compression spec's say the ideal length for the 3rd harmonic is 14.942", including the port length in the head which is between 3 and 4 inches. So a 10" intake tube. Metal, especially light weight aluminum, shouldn't have any issues supporting it's own weight as long as it's not paper thin.
The bigger question I had was if you were using a 12 port head or if your intake ports are combined? If still open then that is another whole set of crazy air flow dynamics I don't know what software/calculation would model that well.
From PipeMax. - Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner ) 1st Harmonic= 37.709 (usually this Length is never used) 2nd Harmonic= 21.402 (some Sprint Engines and Factory OEM's w/Injectors) 3rd Harmonic= 14.942 (ProStock or Comp SheetMetal Intake) 4th Harmonic= 11.760 (Single-plane Intakes , less Torque) 5th Harmonic= 9.542 (Torque is reduced, even though Tuned Length) 6th Harmonic= 8.028 (Torque is reduced, even though Tuned Length) 7th Harmonic= 6.928 (Torque is greatly reduced, even though Tuned Length) 8th Harmonic= 6.094 (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 = 2.032 to 2.286 Sq.Inch Plenum Runner Average Recommended Entry Area = 2.337 Sq.Inch Plenum Runner Maximum Recommended Entry Area = 2.387 to 2.825 Sq.Inch
Minimum Plenum Volume CC = 525.3 [typically for Single-Plane Intakes] Minimum Plenum Volume CID= 32.1 [typically for Single-Plane Intakes] Maximum Plenum Volume CC = 4093.2 [typically for Tunnel Ram Intakes] Maximum Plenum Volume CID= 249.8 [typically for Tunnel Ram Intakes]
