Quote:
Originally Posted by racing97
Good edit on the counterweights Green, The Porsche engine is a boxer but it does not have a 180 crank the 914 does the porsche 911 has journals placed at 120 intervals and is not on a flat plane 3 up 3 down it does have aspiration periods that complement each of the banks that allow you to tune 123 into a collector as well as 456
regards
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The 911 engine is a boxer engine. The crankshaft has individual rod journals placed 180º apart. However, each cylinder does fire at 120º intervals which creates an overlap to help smooth power applied to the crank.
While inherently balanced, opposing boxer cylinders are physically offset from each other (not totally opposite) which would introduce some secondary imbalance. However, there are six cylinders, enough to compensate, and more tend to minimize the cylinder offsets. Boxer engines with fewer than 6 cylinders, e.g. 4 cylinder BMW engines as used in their motorcycles, must deal with this cylinder offset and resultant imbalance in their own way.
This link contains a chart that describes most engine configurations and their basic inherent characteristics:
Flat-4 engine - Wikicars
Sherwood