Does anyone know how GM populated this table? It seems like the L30 and L31 tables should have some type of relationship that's easy to see. Base engine friction seems like it's going to be affected by stroke and bore more than anything else. The L30 and L31 are very similar, with the only major difference being the bore and possibly a slightly smaller cam on the L30. Yet comparing this table between the two engines shows some unexpected differences. Has anyone played with this or maybe heard something about how the tables were developed? Any theories???