Why carbon fibre engines haven’t broken into F1

The first documented use of carbon fibre in motorsport was when some filaments gathered together as a light tow or string were used to reinforce the bodywork of the Ford GT40s that raced at Le Mans. The strands were laminated onto the glass fibre bodywork in a large criss-cross pattern which was very sparse since the cost of the fibres was $1,000 per kilogram. That equates to nearly $9,000 per kilogram in today’s money.

At the time it was an exotic material and, while it promised much, the costs kept usage limited. Today a general-purpose fibre such as T800 is under $30 a kilogram, cheap fibres half that and high-performance materials such as T1100 only around $100 a kilogram. Properties have improved no end with those early fibres having a tensile strength of around 2.5 Gigapascals (GPa) while the soon-to-be-available T1200 will reach 8GPa.

To set some background to composite use
in engines, in 1981, as well as being involved in Toleman’s transition to Formula 1 from
Formula 2, I was tasked with supervising the deployment of the previous season’s championship-winning F2 design to customers via a replica built by Lola. This involved assisting works-supported cars run by Alan Docking for Stefan Johansson and Kenny Acheson. These cars were to use the Hart 420R engine but, early in the year, we came
across a fascinating individual by the name of
Matti Holzberg who was claiming he could build
an engine largely out of carbon fibre.

While this seemed a fanciful idea, a little due diligence convinced me that what he was proposing was not just feasible – but that he had taken it to a demonstrable point which gave all of us the confidence that we could incorporate the engine into the Formula 2 car. At this stage, Matti had built and run a four-cylinder engine which proved the concept and actually performed pretty well.

For the F2 car, we needed to upgrade this to a full race specification with a four-valve per cylinder head, a dry-sump lubrication system and the various other accoutrements that a full race engine required. Matti set about this and we, while building the cars initially with the aluminium Hart engine, looked into the installation requirements such as the cooling system which was a bit of an unknown given the difference in thermal conductivity between aluminium and carbon fibre composites.

I was keen that we did not stress the engine as, in the early days of composite technology, we weren’t certain of the properties of composites at temperature. In fact, a spectacularly unsuccessful experiment of trying to make the rear engine pontoons of the F1 car in carbon did nothing other than increase my concern over our lack of knowledge of this new ‘wonder’ material. As it happened, the design of the F2 car was ideal to relieve the engine of any structural road loads, so we continued with optimism.

Photo by: Sutton Images

Financial reasons meant the heavier Hart engine was used in Toleman's F2 cars in 1980

The proposed engine was due to weigh in at 82kg, which was 24kg lighter than the Hart engine. In a series as closely contested as the European Formula 2 championship was in those days, the thought of getting to the weight limit with a significantly lower centre of gravity was extremely attractive.

So why did we never see a carbon fibre engine in a Toleman F2 car? The answer came down to money. Even with sponsorship from Marlboro and RMC the F2 works-supported programme was run on a shoestring. The development of the race version of the engine was never going to be cheap. Matti had interest from Ford, which was keen on running the engine in IMSA Capris, but this came to nothing.

Undeterred, he carried on in IMSA with backing from Amoco Chemicals and the engine did race in its full competition version – I wish we had been able to bring it to a wider audience in F2. I do, however, gain some satisfaction from the fact that the IMSA car retained the engine mounting system designed for the F2 car – a small but significant emblem of its heritage. In the mid-1990s the engine also appeared, with some success, in a Vision in the British Hillclimb Championship.

The initiative started so many years ago by Matti Holzberg lives on through the Polimotor project and the latest version of the engine has moved from composite fabrication to injection-moulded techniques

So, forty years on, why haven’t we seen a carbon fibre engine in F1, particularly given the incredible improvement in fibre properties and resin systems in that time? The answer, unfortunately, lies in regulatory prescription. It would be perfectly possible now to make a significant number of engine components from carbon composites even if certain items might still require manufacturing from materials with better high-temperature physical properties, but the regulations are very specific in this area.

The initiative started so many years ago by Matti Holzberg lives on through the Polimotor project and the latest version of the engine has moved from composite fabrication to injection-moulded techniques. The majority of Polimotor components are now made from polyamide-imide resins with graphite, glass or titanium reinforcement as a composite. As well as weight saving the components can reduce inertial forces within the engine, giving additional weight saving on some of the remaining steel parts.

The temperature, time and other process variables differ between parts but, in general, the component is first injection-moulded and allowed to cool past its plastic deformation temperature. It’s then post-cured by solid-state polymerisation at a series of temperature steps to increase its molecular weight. This is performed in an inert atmosphere which helps to expel by-products of reactions until the polymer is chemically stable.

While we’re still some way off seeing such engine construction become commonplace even in F1, the continual development of carbon fibres and the resin systems involved could one day see an engine with major components made of ‘plastic’.

Photo by: GP Racing

Holzberg has continued to develop his Polimotor carbon fibre engine