Benifits of short runner intake on F/I

[ProdigalSon 1]

OK, so willing to be corrected on this:

 

1) Plenum width/depth must be at least 1.5 times the runner width, and must extend a bit beyond the last runner to avoid mismatches in fuelling (eg. when the last runner has more fuel and the first runner has less because the mixture tends to be directed into the last cyl...)

2) The diameter of the runner(s) determines the max. horsepower, as it eventually becomes the limiting factor in the air/fuel delivery (will try to get some figures, but 50mm = 400bhp IIRC)

3) Long runners increase low end torque at the (slight) expense of less high end power, short runners flow better at high rpm but rob low/mid range torque

4) 4 different length runners will spread the torque curve between the 4 cylinders, as each will be tuned to a slightly different power/torque band

 

For example, the stock G60 inlet:

 

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Will check the accuracy of that when I get a chance...