Originally posted by JimCulp
Actually Garen and SCHNELE I think you are right- I had it backwards.
Nope, Jim, you were right. Long runners shift the Volumetric Efficiency of the engine towards the higher end of the RPM range. Look at it from an inertia perspective; a column of air at rest, tends to stay at rest. A column of air in motion, tends to stay in motion. Longer runners increase the cylinder filling efficiency at high RPM's......kind of a ram effect. If you look at the Can-Am cars of an earlier era, you would find the normally aspirated engines were tuned to the track they were running. High speed tracks like Road America, the engines had high stacks. But on shorter tracks, where exit speed made all the difference, short runner tubes were used.
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, 8:41 R&P