I was watching a typical car show on TV and an unusual comment was made that caught my interest. There were 2 hosts and they were talking about how a crankshaft in an engine can give a car a different exhaust sound.
I had never heard anything like this before so my interest was peaked. The new high performance Shelby GT350 Mustangs have a different sound than most other Mustangs and this is a result of having a Flat Plain Crankshaft while other Mustangs have a Cross Plain Crankshaft.
Flat Plain Crankshaft vs Cross Plain Crankshaft
A Flat Plain Crankshaft is not new. It was used in many early engines since it is easier to manufacture. These crankshafts are generally used in smaller displacement engines. North America is known for its big displacement power plants so the Cross Plain Crankshaft has become the standard.
The Flat Plain Crank gets its name from the flat appearance of the part. The journals are on a 180 degree plain across from each other. The Cross Plain Crankshaft has its journals at 90 degree increments or 2 plains across the shaft.
Some of the advantages for Flat Plain are higher RPM, less weight and more efficient tuning. The downsides include rough idle and in some cases shorter engine life, a result of vibration.
Below is a Youtube video that gives a much better explanation in these Crankshafts then I can.