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tjts1, the 3 liter Porsche 4 cylinder had at least one balance shaft (twice engine RPM), maybe even two. Think the balance shafts were pioneered by Mitsubishi, but there could have been an earlier version.
The problem with 4 cylinders above 2.4 liter is they develop a harmonic porpoising motion from front to back when they go beyond 2.4 liters. Not sure of all the physics involved in that but I know it is generally understood among engine makers.
I know the Cummins and many other engines are larger displacement than 2.4 liters. I won't guess as to why they do not suffer from the same symptoms of front to rear engine rocking. It may be their mass, RPM, the fact they are diesel and not gas.
Maybe someone else has more info. I just feel like you can power virtually any vehicle up to two tons with 2.4 liters of 4 cyl. The wife's Sorento does it nicely at 3800 without passengers, with 2.4 liters and could provide much more power (which she never needs) with a turbo.
regards
Mech
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