Re: straight-6 vs. v-six (archive)

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A direct answer to your question: the obvious is that a straight six has six cylinders all in a row, lined up and connected to a crankshaft that has has six places to connect to, called "throws".This arrangement is intrinsicly smooth in operation,(when the throws are arranged so that there is a power stroke from each cylinder in six equally spaced fractions of the crankshaft's rotation). They are relatively easy to design and build.

A V-6 has two rows of cylinders arranged around the crankshat in a "V" shape when viewed from the end. There are varieties of angles that can be used, the most common are 90* and 60*. They are complex to design and build compared to a straight six. But the shorter crankshaft, compact size, and more direct access to the intake ports makes them desirable just the same.

As far as power is concerned (I'm sure I'll hear about THIS one!) neither configuration is in and of itself at an advantage since any engine is little more than an air pump. The torque an engine produces is the result of many complicated factors, but the horsepower is a mathmatical result of the RPM the engine is turning when it is developing that torque. Given the same torque, the engine that makes it turning at the higher RPM will be the H.P. champ. (again, more complicated factors)

My guess is that since straight sixes have been around so long,and V-6's are recently popular, more "clean sheet of paper" design has gone into the V-6's resulting in the perception that a V-6 is more powerful. Indeed a short-shafted V-6, if properly designed for the stresses of high output, is capable of holding up better under extreme outputs (Can-am V-6 Buick stock-blocks putting out a reliable 1200 H.P.)

I don't know why BMW hangs on to this (wunderkind)six, except it is a work of art. Hard core E21-ers and '02-ers may not have had the "BMW six epiphany". If not, you owe yourself the treat of one at full song. This month's _Roundel_ mentioned that BMW is working on a V-6, though.....the king is dead..long live the king!?
Tom

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