[immortal_suby]

Originally Posted by Ownbot

1. If a boxer engine is such a good design then why doesn't any other cars currently use them? Don't even mention Porsche because that is comparing apples to oranges. And airplanes? Once again apples to oranges. Airplanes are meticulously maintained and are checked before and after every flight. Whats the big advantage in a boxer engine? Lower weight distribution, that's it. Wow that's impressive.

There are so many reasons that a flat 4 or 6 or an inline 6 are better design than any others. It is puzzling why more carmakers don't adopt them but it could be explained in that they would have to redesign many other parts of the engine compartment and components just to make them fit. They are wider and shorter and sit lower - all things that might interfere with the layout of the suspension, steering column, steering rack, etc.

Here's a short excerpt I just dug up that is not any part of a subaru advertisement.

There are four different forces and moments of vibration that can occur in an engine design: free forces of the first order, free forces of the second order, free moments of the first order, and free moments of the second order. The straight-6, flat-6, and V12 designs have none of these forces or moments of vibration, and hence are the naturally smoothest engine designs. (See the Bosch Automotive Handbook, Sixth Edition, pages 459-463 for details.)

Engines with particular balance advantages include:

* Straight-6
* Flat-4 with two geared crankshafts
* Flat-6
* Flat-12
* V12

Engines with characteristic problems include:

* Straight-4 using a single crankshaft have no better kinetic energy balance than a single, and require a relatively large flywheel.
* Crossplane V8, which requires a very heavily weighted crankshaft, and has unbalanced firing between the cylinder banks (producing the distinctive and much-loved V8 "burble").
* Flatplane (180° offset crankshaft) V8.

In modern multi-cylinder engines, many inherent balance problems are addressed by use of balance shafts. Wear-and-tear is reduced only when the crankshaft is partly balanced before it touches any bearing as it is done in the flat and the V-engines. A balancer shaft transfers its force via bearings onto the crankshaft and rather increases wear-and-tear.