Cosworth V-8 3-Litre Formula One


Written when it first tested

First time an engine was used as part of the car structure

ALTHOUGH THERE is still no literally, all American effort in Formula 1 racing, the addition of Ford to the list of engines competing seriously under the formula certainly gives Americans a better chance to identify with some of the machinery-along with Dan Gurney's Anglo American effort that has resulted in the Eagle-Weslake cars. Not that Ford Dearborn is intimately involved, however: Ford of England is in charge of the new engine, and in turn has farmed out its design and development to the respected Cosworth firm. The Formula 1 engine is the second phase of a $280,000, 2-phase program-the first of which was the Formula 2 engine based on the Cortina block.

At the outset Ford decided that a V-8 was the way to go, the apparent reason being to relate the F 1 engine as much as possible to the production-block-based F2. But of course the Fl rules do not confine any engine to a production base, so that even though the two engines share plenty of design features the new V -8 is a completely separate entity.

Now, it is a fairly well known fact that the theoretical power available from a given displacement goes up with the number of cylinders. The effects of friction on output, and complication on reliability, put a limit on the practicability of this theory and BRM's recent experience with the H-16 seems to place that limit at 12 cylinders for the present. Eight cylinders, then, cannot be expected to produce the ultimate power from the 3 liters allowed-so Ford and Cosworth knew they had to concentrate on combining the engine with a lighter, simpler car.

Colin Chapman, chosen to do the chassis, was party to the decision to go ,to lightness and simplicity. His approach was this: to make the engine a part of the chassis structure (much in the manner of De Tomaso) to achieve the lightness necessary. Thus the engine could not be designed apart from the car; the engine will not be adaptable to any other chassis. In fact the very first sketches of the engine included rear suspension linkage and body panel outlines.

Shape and Layout

ONE OF THE major design problems in a Grand Prix car is to leave room for enough fuel to complete a race without a stop. Another is to get the fuel tank or tanks in a place where the use of fuel affects the weight distribution as little as possible. So designer Keith Duckworth aimed for an engine short enough to leave room between itself and the driver for a large fuel tank; thus located, the tank is close to the car's center of gravity. Too, a tank here could go within the minimum frontal area of the car-desirable for obvious reasons. Though the V-8 engine as a type is wide, the cylinder head design has kept width to, a minimum. In addition, the designer took pains to keep the engine "tidy" with Its accessories and ancillaries protruding as little as possible from the basic shape.

The basic shape chosen is a 90 degree V-8, 21.4 iri. long and. 27.0 in. wide overall. Cylinder centers are 4.100 in. apart, and the dry sump extends only 5.25 in. below the crankshaft centerline. Overall weight of the unit is 370 lb with clutch. Bore and stroke are 85.7mm x 64.8 mm, giving a displacement of 2993 cc.

Reciprocating Parts and Crankshaft

AS IN MANY racing V-8s, a single-plane crankshaft was chosen. This gives even firing intervals for each of the two banks (making it in essence two "fours") and thus allowing for the easy concoction of two simple extractor exhaust systems rather than the bundle of snakes common to two-plane crankshaft V-8s. The secondary vibration forces from pistons and rods aren't in balance with a single-plane, but the resulting roughness of running is easily acceptable in a racing engine. The shaft is a nitrided steel forging.

Rods are of forged steel and, at 5.23 in., are over 4.1 times as long as the crank throw-result: minimal secondary vibrations, piston acceleration and side thrust. The pistons are forged aluminum alloy with solid skirts and have three rings: Their crowns are flat with valve recesses which become a large portion of the combustion chambers.

Cylinder Heads

THE TWO HEADS are interchangeable and have inlet ports on the inner side of the V, exhausts on the outer Combustion chambers are flattened, compact pentroof style, for with four valves per cylinder it has not been necessary to incline the valves so much to get space in the chamber for adequate valve size. The included angle between the valves in end view is 32 degrees, symmetrical about the cylinder axis. Inlet valves have 1.32-in. heads, exhausts 1.14-in. heads.

Because of the unusually large loads applied to cylinder heads that will be part of the car chassis, there are 18 studs holding the heads to the block No head gaskets are used, but "0" rings do the sealing at cylinder liner flanges.

Valve ports are almost straight; each pair of ports (for two valves) blends into one port before reaching the outer face. The head castings are only 3:765in. deep and because of the small valve angles are relatively narrow. Above the heads go the cam carrier castings, each one incorporating its 16 tappet guides and the lower halves of 10 camshaft bearings (5 per shaft). The camshafts are of chilled cast iron and run in steel-backed shell bearings. The two upper chassis-mounting points are extensions of the valve gear coverplates, and stresses from these points are spread by tubes formed along the center of-each cam carrier casting. Holes in this tubular section give access to the plugs.

An indication of the good combustion being achieved in the first test engine is the fact that, it develops maximum power on only 35 degree ignition advance, vs. 50° from the old 2-valve Cosworth-Cortina. Incidentally, no centrifugal or vacuum advance is needed in a racing engine of this sort, as it doesn't have to operate satisfactorily over a wide speed range. Small favours! The valve gear is safe for 11,500 rpm.

Block and Crankcase

THIS MOST conventional part of the engine is an aluminium alloy casting, comprising the two cylinder banks and upper half of the crankcase. The steel wet bore liners are located by top flanges and sealed at the bottom by "0" rings. There are five main bearings; the sump casting includes the bearing caps and the bottom forward chassis mountings and is stiffened by an integral cooling cross tube and longitudinal structural tubes.

Timing and Auxiliary Drives

BECAUSE OF the insistence on compactness, there are no undue "bumps and humps that would require" power bulges in the bodywork: water and oil pumps are down at the sides where the engine is narrowest. All auxiliaries originate from the crankshaft nose: 2-stage gearing drives a half-speed shaft between the two banks; from there two gear trains take the drive to a central gear on the front of each head which then drives its two camshafts. A pair of gears at the center of the half-speed shaft drives a shorter, higher shaft that runs the fuel-injection metering unit, alternator and distributor. The nose of the half-speed shaft has a cog-belt drive to two more shafts, low on either side of the crankcase: both have water pumps, the left has an oil pressure pump and fuel pump, and the right carries two oil scavenge pumps.

Power Output,

AT PRESENT "the eingine is developing about 400 bhp@9000 rpm. a competitive power output already at a lower-than-usual speed. There is plenty of scope for development to higher speeds, and thus higher power, in the future.

But there is scope for development in the other F1 engines and it is certain that any real edge the new Lotus-Ford may have on the F1 circuits will come from the overall vehicle concept of a lighter, more compact car possible with this engine.


Author: ArchitectPage