It's related to crankshaft rotation. In a vee type engine it's
quite common to have two opposing piston rods share the same crankshaft journal.
In the case of the DeLorean the vee configuration has the cylinder banks 90
degrees apart. This all works out to the two cylinders sharing the crankshaft
journal rotating the crankshaft different degrees of rotation. When the first
cylinder fires the crank rotates 120 degrees. The second turns the crank 60
degrees, the third 120, the fourth 60 and so on. When a V-6 is banked at 60
degrees it becomes an even firing engine. When a 90 degree vee becomes a V-8 it
becomes an even firing engine. It's just the way the math works out. If youwent
to the expense of casting a crankshaft with a separate journal for every
cylinder then even the 90 degree V-6 could be made even firing. The most
obvious detriment to odd firing is an inherent engine shake. The DeLorean
doesn't shake but it's not particularly smooth at idle because of this. Some
manufacturers have added a counter rotating balance shaft to overcome
this.
Bruce Benson
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