Under The Hood: No sign of truce in battle of blocks

Most vee engines have six or eight cylinders. Photo / Supplied

Road rage has nothing on the carnage that can occur when a couple of opinionated car-owners get caught up in block rage, that little-publicised but dangerous condition that sometimes afflicts proponents of inline and vee engines.+

Driven has seen sane and sensible motorists all but frothing with rage when one dares suggest that an inline block is better than a vee, or vice-versa.

The only thing that's going to stop them is if someone else unwittingly suggests the flat-engine configuration or a rotary is better.

We'll leave the pros and cons of the flat and circular engines for another day, because the two key letters in the block-rage alphabet are I and V.

The debate can take part in all sections of motordom, such as between the owners of BMWs, which generally come with inline engines, and Mercedes-Benz, which is now big on vees, but used to like inlines.

It may be between Falcon (inline) and Commodore (vee) owners, or even within the Aussie Ford family itself, as in FPV F6 owners (inline six) who insist that GTs (V8) are a waste of engine-bay space.

So what's the truth of it all? What are the benefits of the two layouts and, at the end of the drive, which is best?

The basics: inline engines, as the name suggests, have their cylinders in a single row. It's a common arrangement for up to six cylinders.

Vee engines have their cylinders arranged in two banks at an angle to one another. Vees have appeared with as few as two and as many as 24 cylinders, but their overwhelming use today is six or eight cylinders, with a sprinkling of V10s and V12s.

The type of car being designed strongly influences its engine configuration. A small econobox will usually use a sideways-sitting inline four, because it takes up so little room.

But a peppy family car might benefit from a six-cylinder engine and a compact V6 may be the ticket. If the designers like the idea of a longer bonnet on the same sort of car, they may go for an inline six.

An inline engine may be lighter than a vee equivalent - an important consideration when distributing vehicle weight and pruning the fat for maximum efficiency.

Not lost on the accountants is that a straight engine can be cheaper to build. Its cylinder bank can be milled from a single casting and it requires one less cylinder head and set of overhead camshafts.

Inlines have ruled the four-cylinder world, with flat fours a distant second. A few V4s have appeared in mass-market cars.

Both vee and inline versions have shared the six-cylinder world since the V6 was introduced by Lancia in 1950. But nowadays the V6 is dominant. Although perhaps not as naturally smooth as an inline six, the vee is shorter and lower, so it's a better fit for many of today's cars.

Often, cars designed primarily for an inline four can also take a compact V6, allowing a much wider model range. The more models a carmaker can spin off a basic design, the better for its bottom line.

Meanwhile, Volkswagen and earlier Lancias attempted to combine advantages of the straight and vee configurations by building a narrow-angle vee that's more compact than either of the main configurations.

And the big question? Sorry, you're not going to draw Driven into the debate over which configuration is best; it's much safer sitting on the fence.