Air intakes

A designer’s expression

It would be unwise to say when the first carburetter air intake appeared on a racing car, but it was certainly long enough ago to be academic. In the mid-thirties the Barnato-Hassan Bentley had a forward-facing air intake for its SU carburetters and it was calculated that it produced 1/2-lb./sq. in. supercharge at 140 m.p.h. More important than any increase over atmospheric pressure that an air intake provided, was its ability to provide the engine with cold air, rather than the warm air from under the bonnet. Air intakes to engines became very popular in the 1952/3 Formula Two days, and they varied from calculated forward-facing ducts, to hit-and-miss scoops and even went through a phase, with Maserati and Gordini, of facing backwards, the theory being that engines liked to breathe still-air and not turbulent air that was rushing uncontrollably into a forward-facing duct.

When the present Formula One, for 3-litre engines, began in 1966 the air intake had died a natural death, and all the early 3-litre engines, of V8 or V12, and even H16, cylinder arrangement were left to gasp for air from uncovered intakes to each cylinder, there being various length inlet trumpets in vogue, but no attempts to direct air in their direction. Eventually Matra produced an air-box on top of their V12 engine with a forward-facing scoop, and nobody took it very seriously for it appeared to transgress the rule about the height of the car above the crash-bar. Matra convinced the powers that be that their air-box was not part of the car, but part of the engine, and the rule makers had to agree that the law did refer specifically to the car and not the engine. Tyrrell then appeared with an air-box on the Cosworth V8 engine, and then there was a mad rush to design air-boxes for feeding cold-air or ram-air to the various Cosworth engines, and the BRMs and Ferraris.

From rather cautious beginnings the air-box grew and grew until it is now a major part of today’s Formula One car and each designer has his own theories and his own method of arriving at an answer. These vary from intricate calculations to guesswork, and the various shapes that are used are arrived at by some pretty devious means. The interesting thing is that each make of car has its own distinctive air-box and you get the feeling that the designer has projected his own personality into the shape of the air-box in just the same way that designers used to project their personality into the old-fashioned radiator or radiator cowl. One could easily distinguish a Bugatti or a Delage by the shape of its radiator and today you can easily distinguish a Tyrrell from a BRM by the shape of its air-box.

Discussing these appendages with the various designers produced some interesting conversation, especially about the methods used to arrive at the size required, and then the reason for the shape. Most started with a sum involving the quantity of air the engine was going to need and this was transformed into an area in square inches. The quantity was arrived at by different means, from the total cross-sectional area of the inlet ports, to the breathing volume of the engine at certain r.p.m. or at certain power output, and in some cases this area was adhered to, in others a bit more was added for luck. Some worked it all out, the driver tested the car, the area was increased and the driver was convinced the car accelerated better, so the area was increased even more; real scientific stuff!

When it came to the question of the shape of the orifice there were numerous reasons, ranging from a technical theory about airflow to “it seemed a good shape” or “it blended in with the general shape of the car”. One thing that did concern everybody was the fact that the air-box was producing frontal area that got in the way of the rear aerofoil, so that the shape of the box itself was designed either to direct the air towards the rear aerofoil, or to ensure that it disturbed the air flow as little as possible. Apart from providing good advertising areas all the air-boxes in use on today’s Formula One cars are the expressions of the individual designers, and the variety of shapes would indicate either that no-one knows the real answer or the shape is not very important, the main thing being to get cold air (and sand, stones, insects and what-have-you) down into the engine. Just as each designer has his own ideas about the shape of the orifice, so they all have their individual ideas about methods of catching extraneous objects, ranging from wire-mesh to baffles, and some think that heavy objects will be carried along in a horizontal plane by their inertia, while the air swoops down to the engine, while others assume the grit and sand will follow the path of the air.

When the old fashioned radiator disappeared, there were people who lamented, but were consoled by the new-fangled cowlings that covered the unromantic square radiator core. Then the radiator cowling disappeared and there was more lamenting, but relief was found in the shapes of the nose cones that covered the front of the car (remember the shark-nose Ferraris and the Eagle’s beak). Then along came the wedge nose, as perfected by Lotus and there was more lamenting. Take relief now in the shapes of the air-boxes, they really are as distinctive and fascinating as a Bugatti or Rolls-Royce radiator, and just as functional—D.S.J.