Do the eyes have it, or is it in the Vees?

By T. Uncle

In this age of reason, it would appear sensible to imagine that automotive designers have more or less established the best way to configure an internal combustion engine.

A hundred years of research, experimentation and a fantastic collection of failures and triumphs would, sensibly, have led to a reasonably fair idea of what works best.

Of course, that's not so.

While engine designers have rarely disagreed on the basic principles of a regular internal combustion engine (Felix Wankel's rotary is an exception, but look how successful that has been), they still appear undecided on whether it should be in Vee configuration, straight, line-ahead configuration, or horizontally opposed as in today's Subarus and Porches, or yesteryear's Volkswagens.

That said, the indications today are that, in anything above four cylinders, the Vee configuration appears to be gaining popularity. Why is this so?

Basically, the concept came into being as a way of maximizing the number of cylinders while minimizing underhood space.

With its cylinders arranged in two separate rows, inclined away from each other at a roughly 60-degree angle but meeting in a common crankshaft, the overall length of a Vee engine is roughly half what it would be if the cylinders were aligned "conventionally".

The most famous example of mass-production Vee engines was Henry Ford's utilization of the V-8 in the 1930s.

The compact eight-cylinder engines of that era contrasted with the gargantuan inline engines used by Ford's main rival, the General Motors Corporation.

The straight eight Buicks of the time were impressive for their smoothness, but they were greedy for space and created some startlingly elongated bonnet lines.

In America, the V-8 eventually became the industry standard, adopted by every other carmaker, including General Motors, as a largely token attempt at design efficiency and effective space utilization.

Today, Vee-engines are increasingly widespread, making their way into the uncompromisingly efficient designs of carmakers such as Mercedes-Benz.

The German manufacturer today has "modular" V-8 and V-6 lightweight engines in its lineup, while competitor BMW not only has V-8s, but also a massive V-12.

The pacesetting American company, Chrysler, offers a unique proposition in the world of road cars with its V-10 Viper sports car.

The massive eight-liter engine is big enough and powerful enough to outaccelerate a Ferrari from rest to 160-something, without shifting out of top gear.

But Vee engines are not just aimed at the muscle market. The Mazda Eunos 30X has a front-drive V-6 with a capacity that goes as low as 1.6 liters according to the model.

In some cases, small capacity and high-revving, shrieking energy can be rolled into one, as was the case with the 1000-plus horsepower turbocharged V-8s used in some Formula One vehicles of the mid-1980s that displaced just 1.5 liters.

Makers like Subaru and Porsche argue that while Vee engines are okay, the best possible configuration is the flat, horizontally opposed type. They cite the configuration's low center of gravity -- the cylinders operate horizontally at the same level as the crankshaft -- and perfect balance -- the opposing pistons push and pull on the same plane -- as things that should be obvious to other engine designers.

What they don't mention is that ease of maintenance isn't a strong feature -- try getting to the spark plugs of a Subaru -- or that the flat configuration always makes for a very wide engine that must be specially catered for in the design of the engine bay.

It also tends to place the electrics in a more moisture-prone location than an upright, inline layout, which can raise the likelihood of potential problems in some damp countries.

However, the configuration being worked over and refined with the greatest gusto is the V-6.

The V-6 is finding its pace under the hood of both front and rear-drive designs, but is especially prevalent in the latest crop of Japanese front-drive sedans.

Up to 3.5-liters in capacity, they are commonly installed laterally across the engine bay where they present an interesting problem for exhaust manifold designers. They must route the pipes from the three front cylinders as efficiently and unobtrusively as possible towards the back of the car, meeting a single catalytic converter somewhere along the way.

Honda has adopted a classical, simple approach with its V-6 Legend by aligning the engine from north to south, and allowing an admirably neat and efficient exhaust system.

The Japanese designer, known for its elegant engineering, reasoned that a V-6 engine was greedy on neither length nor width, and was therefore equally space-efficient, whether installed longitudinally or laterally.

The only real fly in the ointment is that, unlike an east-west engine, the north-south configuration requires the rotating forces generated by the engine to be turned at a right angle to drive the wheels.

In an east-west design, the engine's crankshaft is spinning along the same plane as the wheels.

V6 space efficiency is taken to its most extreme by the former flat-four proponent Volkswagen.

The extremely narrow V-6 engine used in certain Golf and Passat models has the tightest angle yet between cylinders -- 15 degrees rather than the more common 60 degrees -- and although it has a capacity of 2.8 liters, it takes up much the same space as an inline 2.0 liter four-cylinder.

The cylinder heads are brought together close enough that only one casting is used to cover both banks of cylinders -- much the same as the V-4 engine used in Lancia Fulvias during the 1970s.

Reportedly, the main problem VW had to overcome with the tight little V-6 was finding a way of cooling it effectively -- the close arrangement of overlapping cylinders created a "hot spot" in the middle of the Vee and required careful design of the cooling passages built into the block.

This was nothing compared to the design challenges faced by Audi, which displayed a remarkable W-shaped engine in the early 1990s with a radial-style cylinder arrangement using three groups of four cylinders to drive a single crankshaft.

A bit like a normal V-8, with an extra bank of cylinders comfortably resting in the valley between the outer cylinder banks.

The problems of designing the manifolding -- both exhaust and inlet -- must have been considerable, let alone figuring out how to conduct service and repair operations.

This approach is one probably best left to the aeronautical field, which once made heavy use of multicylinder radial engines. Aircraft engineers could at least strip away all the cowling to gain access.