Guaging Interest Excessive Manufacturing Intake Plenum GB
You should add in the volume of one runner also to the plenum volume. Most shoot for 1.5x engine displacement or greater. Some of the evo manis are approaching 2.5x displacement. Not always practical because of space constraints.
I would like to see the design with shortened runners. Somewhere in the 11" range from intake valve to plenum.
Guaging Interest Excessive Manufacturing Intake Plenum GB
I checked the clearance on the NA mani, and no spacer needed as is with mine.
The plug access as I mentioned before will not happen without shorter runners. As a guess I would say minimum of 3" shorter would be needed for plug access.
TT runners are 11 inches, NA runners are 9 inches. 9" is the shortest length you can have without a spacer. The top of the rear valve cover gets in the way of the tank.
http://img.tapatalk.com/d/13/11/17/6y2abe4a.jpg
Runner profile as requested.
http://img.tapatalk.com/d/13/11/17/y5emy5a5.jpg