In my opinion the tuned length of the system is important in achieving the torque results that you want at certain engine speeds. The same applies to the exhaust system. Tuning the two together can no doubt be done by skilled engineers with mathematics but us mere mortals have to do it by common sense and trial and error.

From what you say Heinz you have used good logic and experimentation to arrive at the point you wanted. I suspect a shorter tube may produce good results at higher revs whereas the longer tube that you have used has a more "broadband" effect. The long tube would cause a build up of momentum of the mass of air that would cause an increase in pressure, a ram effect, when the intake valve closed and generally increase the charge in the cylinder when the valves opened.

Just my guess.

Peter

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