Common plenum or individual runners???, for gas milage and drivability Options

[Mueller]

for my 2316 it seems that the stock plenum might be reaching it's limits as far as volume goes.....so, I either fabricate a larger common plenum, or go with individual throttle bodies such as TWM or Jenvey*

single plenum would be easiest, but the individual throttle bodies look better (IMG:style_emoticons/default/smile.gif)

has anyone switched from one to the other on the same motor with everything else being the same???



*Jake Raby is the U.S. distributor of these....

[ottox914]

My very basic understanding of plenum and runners VS throttle bodies: when the intake valve closes, the incoming air charge is still on its way, hits the closed valve, and bounces backwards thru the intake runner and into the plenum. By doing the math (not my strong suit) you could take in to account the speed of the "bounce back", the volume and shape of the runner, size of the plenum, and calculate lengths for runners, and capasity of plenum, such that when the incoming air charge bounces off the plenum, and rushes back down the intake runner, that it gets back to the valve as it is opening again, resulting in better cylinder filling, sort of a "super chargeing" of the intake charge. Down side to this is that is is pretty rpm dependent, based on length of runners and timing of valves opening/closing, hence some cars w/variable length "tuned" intake runners. The individual throttle bodies, if run open topped, have nothing for the charge to bounce back off of, but do offer lots of air flow and a more direct path at higher rpms. If they are run w/air cleaners, again, the overall length of the intake, from the top of the air cleaner (or thorttle plate?) to the valve is likely to be less than the stock T4 system, and the bounce back effect happens faster, and therefore provided more benefit at higher rpms, when the valves are open/closeing faster.

Thats all I think I know, if someone knows more feel free to correct me.