Buick's New Even Firing 90° V-6 Engine

The new 3.8 litre engine is a 90° V-6 even firing design.

This engine features a new split-pin crankshaft which changes the timing intervals from the original 150° - 90° - 150° - 90° - 150° - 90° to uniform firing of 120° between cylinders.

Accomplished without changes to the original cylinder block, the new crankshaft design required that changes be made to the connecting rod and bearing and timing changes to the ignition and valves. Structural changes were made to the crankshaft and piston to reduce stress and provide excellent durability.

The engine balance of a 90° even firing V-6 engine has primary rotating unbalance of varying magnitude and cannot be reduced to zero with crankshaft counterweighting. This characteristic offers the opportunity for several final balance selections which are presented.