When talking about cars specifics, one very important aspect to discuss is the chassis. Truth be told, fully understanding the meaning of what role the chassis covers inside a vehicle, and why it represents a key aspect to understand not only how the car itself will perform but also which principles is the manufacturer following with it, is not entirely clear to everyone. Chassis are much more complicated than they look, and latest innovations surely have made them even more so.
However, it is acknowledged by all car enthusiasts that there have been some major steps in progress in this area, which have revolutionized the industry as they happened. The passage from body-on-frame to steel unibody for example. Alternatively, in the motorsport, the “sandwiches” and the progressive use of carbon fibres. There is also one key moment, which everybody knows about and talks about whenever the subject comes along, which is the use of the engine as a stressed member in racing cars.
“A stressed member engine is a vehicle engine used as an active structural element of the chassis to transmit forces and torques, rather than being passively contained by the chassis with anti-vibration mounts.”
[1]
This definition is solid and very clear. The advantages of such a solution are evident, as its drawbacks, but we will not delve into this particular technical subject in this account. What is the interest of this article, is in fact debunking a myth. To be fair, it is not exactly breaking news, and who works in the field already knows what we are going to illustrate. Nevertheless, a good portion of motoring fans and sim-racers still do not, so writing on such topic felt very much appropriate.
When asked about which F1 car has been the first car to feature an engine as a stressed member, the answer you will most likely get will be the Lotus 49. The legendary Lotus Type 49. However, that would be the wrong answer. Not only the Lotus 49 was not the first, but it was also almost 13 years late to the party. The first one being, in fact, the Lancia D50, originally developed in 1954 and officially raced for the first time during the Spanish Grand Prix, last race of that season. The revolutionary project born out of Vittorio Jano’s genius had many interesting aspects. For example, the engine was put at an angle of 12° to allow the transmission shaft to pass alongside the driver, thus lowering the driver’s seat and improving the centre of gravity, which is incredibly important in a racecar.
The gearbox was coupled with the differential, which while it cannot really be considered as a proper trans-axle, it was still close to the idea and had the optimal distribution of masses in mind. Most evident feature of the D50 then, were the side pods in which were housed two massive fuel tanks. This was conceived in order to improve the aerodynamics of the car, even though, truth be told, it actually worsened the road holding of the vehicle because of the shifting weight as fuel was burned. Finally yet importantly, the engine was developed in order to be installed and used in the chassis as a stressed member. As you can see, there were in fact no mounts above it.
Lancia D50 Engine View, displayed at the Ferrari Club of America national concours in Palm Springs, 2012
It is true however, that when the car arrived at Maranello after the tragedy that struck Ascari, and Lancia subsequent official retirement from racing and devolution of all materials and men from the team to the Scuderia, Ferrari removed this feature from the car (alongside the removal of the side fuel tanks with a more conventional and safer rear one)
[2]. This was both in the Ferrari D50 and in its later evolution, the 801 model.
Forghieri, however, got interested in this particular subject, and when developing the new F1 car for the ’64 season, he designed the 158 to have again the engine as a stressed member, adapting the same solution also for the older 156[3]. These light and not so powerful 1.5 litres cars posed a challenge for designers and engineers while they were raced (from 1961 to 1965), because they needed to compensate the somewhat lack of power with great agility and cornering capabilities. Making them also as light as possible was a solution to make the power deficiency less prominent. The 158 was kind of a revolutionary car too in Maranello, because for the first time in the Scuderia they had developed a semi-monocoque chassis, following Lotus’ example, where the driver was sit in a reclined position. This was supposed to improve the torsional rigidity of the car, while on the other hand it made the car heavier, costs higher and repairs harder compared to the usual tubular spaceframe chassis that the Italians used to run
[4]. The 158 proved competitive though, and in Mexico Surtees was able to clinch the title thanks to it.
Next season, the new engine designed by Forghieri, the 1.5 litres flat 12, was installed following the example dictated by the 158. In the 512, the engine was in fact housed again as a stressed member in the chassis. The car though, unfortunately for the Italians, was not as successful, and it could not stand the competition of Chapman’s Lotus 33 driven by Clark that won, without much trouble, the ’65 championship title.
Ferrari 512 F1 (Nart), Watkins Glen 1964
From the ’66 season onwards, 3.0 litres aspirated engines were allowed by the new FIA regulation for F1 to run, and that caught pretty much everyone by surprise. Ferrari, who ran his cars almost everywhere there was a race, was somewhat ready thanks to the units he had running in the Sports Cars championship. Therefore, he had the 275 P2’s engine stroked to 53.5 mm and that was it
[5]. A 3 litres engine ready to take part in the F1 championship. This engine though, was very heavy, and thus Forghieri, who on the other hand did not consider the solution of having the engine as a stressed member capable of actually turning tables against their competitors, housed it conventionally instead. The ’66 246 F1 however, which was much lighter than the 312, had its thin and compact V6 engine installed as a stressed member. The Dino engine, due to its characteristics, lent itself to the job, and was put in this specific configuration, having races on twisty circuits like Monaco and Nurburgring in mind, where agility matters more than power, even though it is to be noted that it did a fine job even on a fast track like Spa, coming third with Bandini.
As you can see then, the Lotus 49 was not the first F1 car to use the engine as a stressed member in the chassis, but the fifth. Nor it was the most successful using this configuration, since it won just one championship in 1968. The 158 did in fact the same by winning the 1964 season. The Type 49 has been recognized as a revolutionary car, while the only revolutionary thing it truly had was its engine, and the chassis was instead a very simple and standard unit for the day, as claimed by its very mechanics
[6]. The Lotus 49 has become, due to its longevity and the tremendous success of the DFV engine, a legend. Like every legend, it started also many myths, which, as usual, are not always true. Lancia and Ferrari are to be acknowledged as the rightful pioneers in F1 for this progress, which is still relevant to this very day. If manufacturers have voted for the use of V6 turbo engines instead of IL4 turbo from the 2014 season onwards, in fact, is it because the V6s could also be installed and used as a stressed member, while the IL4 could not.
“Render unto Caesar the things that are Caesar's”, as the old saying goes.
Notes:
[1] Wikipedia.
[2]
Ferrari 1947-1997 – The Official Book, New York, Rizzoli Intl Pubns, 2003, p. 50.
[3] M. Forghieri – D. Buzzonetti,
Mauro Forghieri - 30 anni di Ferrari e oltre, Firenze, Giunti Editore, 2008, p. 64.
[4] D. Buzzonetti, M. Forghieri – M. Giachi,
Capire la Formula 1, Bologna, Minerva Editore, 2017, pp. 35-36.
[5] Ferrari 275 P2 Engine Specs: Capacity 3286 cm3 (bore x stroke: 77 mm x 58, 8 mm) – Power: 350 HP at 8500 RPM / Ferrari 312-’66 Engine Specs: Capacity 2990 cm3 (bore x stroke: 77 mm x 53, 5 mm) – Power: 360 HP at 10000 RPM.
[6] I. Wagstaff,
Lotus 49 1967-1970 (all marks) Owners’ Workshop Manual, Sparkford-Somerset, Haynes Publishing, 2014, pp. 94-108.
