I have a buick straight eight engine, 320 ci, in my garage. Unfortunately, it is completely disassembled
because the aluminum pistons were siezed up in the block, and I had to remove the crank to pound them
through---and they did not come out easy.
I am working overseas now, and if I could, I would put it together to test my theories on the subject of
siamese port EFI. My gut feeling is that something is wrong with peoples reasoning that Siamese ports can't be fuel injected.
All engines that have EVEN numbers of cylinders, should have cylinder "Pairs". So if I take cylinder #1 for example at top dead center = 0 degrees, there should be another cylinder paired with it (which I will call it's "brother cylinder"), which is also at TDC = 0 degrees.
And if cylider # 1 is at the top of its compression stroke, beginning its power stroke at TDC = 0, then its paired "brother" cylinder will be at TDC = 0 degrees, but at the top of it's exhaust stroke, just beginning it's intake stroke.
If you have an eight cylinder engine, then there should be 4 paired brothers, and these pairs should be 90 degrees appart----so that pair 1 is at TDC = 0 degrees, Pair 2 will be at 90 degrees, Pair 3 will be at 180 degrees, and Pair 4 will be at 270 degrees.
If you have a six cylinder engine, then there are only 3 pairs---with pair 1 at TDC = 0 degrees, Pair 2 at 1/3 of a 360 degree rotation, and the third pair at 2/3rds of 360 degree rotation.
On my Jeep 6 cyl 258 engine, even though each cylinder has its own intake port, (and if I remember correctly when I was rebuilding it), the "brother" pistons were not adjacent to each other.
At this point I want to make it clear that although "brother" piston pairs are in sync with one another, but because we are talking about a 4 stroke engine, which completes a 1/2 of its mechanical cycle in 360 degrees, and completes its full mechanical cycle in 720 degrees, the two pistons are mechanically 360 degrees out of sync with each other. So while piston 1 is at TDC 0 degrees, at the end of its compression stroke and beginning its power stroke, the "brother" piston is at TDC 0 degrees ending its exhaust stroke and beginning its intake stroke.
So if, a piston pair, were co-located adjacently to one another, and were to share a "Siamese" exhaust port and share a "siamese" intake port, The ports would be in theory, 100% dedicated to one piston at a time, and there would be no valve interference dispute about EFI and "siamese" ports. In theory, if this were the case, the valves on one piston are completely closed, while its "brother" piston goes through the opening and closing of both valves.
So if you look at a crank shaft of the Buick 320 CI straight eight, I think I remember that you can visually see that "Brother" pistons are not co-located together adjacently. And I have heard that the reason they
are never adjacent to one another in sequence is because it causes severe harmonic vibrations.
However, in a straight 4 cylinder car, If I see only 2 siamese intake ports, I think that may be proof enought that the cyliders are indeed paired adjacently in sequence. And if I see 3 ports, (one siamese, and two dedicated), then I can assume that the pairs are not adjacently in sequence.
I wish that I could examine that crank shaft of my straight eight sitting in my garage.
