[Geza-aka-Zombo]

Finally got the opportunity to study my spare intake manifold. With the assistance of my 12 year old daughter, we did some intake runner volume measurements. I was curious if there was any reasoning behind how the manifold was configured by Porsche. Runner volumes range from the high 300 to high 500cc's. This seems to be mostly a factor of space utilization. However, because the volumes do vary, each cylinder will have a slightly different resonant frequency, which would help broaden the torque curve.

The one design feature Porsche obviously included is the firing order relative to the intake plenum "suck side". Being a cross plane crank design, the firing order is such that 2 cylinders on the same side of the engine will fire in succession (1&3 and 6&5). Typically, that second cylinder is starved of air, because a neighbor just consumed a lot of what was there. Porsche configured the intake so inlet air is always pulled into the engine from alternating sides: Left plenum - Right plenum - Left plenum, and so on. This solves that starvation issue - Good job Porsche!

[chalkboss]

This is interesting. What do you plan to do with the data or is this just for curiosity's sake?

[Geza-aka-Zombo]

It was just out of curiosity, and to teach my daughter how to measure the volume using a scale.

[hessank]

Would be interested to know what numbers Carl's honed manifold would produce