In the history of automotive engineering, there are enough stories that sound like outright fiction or garage legends. A car running on water, an atomic car - many automatically attribute the so-called "plastic engine" to such stories. The very phrase seems absurd. How can one even imagine an engine made of a material that is usually associated with bumpers or children's toys? How can plastic withstand the extreme temperatures, pressure, and colossal loads inside an internal combustion engine?
Nevertheless, this story is not a fantasy. It is a real, bold, and in many ways tragic engineering experiment, one of the most radical in the 20th century. The project came surprisingly close to a technical revolution but faced the limitations of its time. To understand how it came about and why it didn't become widespread, we'll have to start from afar.
A World Drowning in Gasoline: The Origins of the Idea
The starting point of this story is the 1970s. In 1973, the world was hit by an oil crisis: OPEC countries imposed an embargo, fuel supplies were reduced, and gasoline prices soared. What seemed normal just yesterday suddenly became a luxury. Huge American cars with gluttonous V8s, which had recently been symbols of power and status, practically overnight turned into a clear example of wastefulness.
Automakers found themselves in a state of panic. They faced an extremely simple and tough task - to make cars more fuel-efficient. The most obvious way was to reduce weight. Every kilogram saved meant a small, but still, fuel saving. Engineers began actively replacing steel with aluminum, but it quickly became clear that this was not enough. A qualitatively different approach was needed, a radical step beyond the usual solutions.
It was in such an atmosphere of total search that ideas were born that would have been considered insane in calmer times.
The Man Who Decided to Abandon Metal
While the entire industry was racking its brains over how to lighten metal structures, an engineer named Matti Holtzberg appeared on the scene. He was an inventor, an engineer, and, in fact, a fan of his work. His approach differed from the generally accepted one: instead of optimizing metal, he asked a question that no one dared to formulate aloud. Why should an engine be metal at all?
Holtzberg had long been interested in composite materials - at that time, this was an area of advanced technology, in demand in the aerospace industry and top-level motorsport, including Formula 1. He founded Polimotor Research and stated that he was able to create an internal combustion engine in which up to 80% of the components would be made not of metal, but of high-strength thermosetting plastics and composites.
The key material for the project became Torlon - a polyamide-imide (PAI) developed by Amoco Chemicals. This was not ordinary plastic, but a real "supermaterial." In carbon or fiberglass-reinforced form, it had a set of properties that looked almost fantastic: strength comparable to aluminum alloys; a density of about 1.4 g/cm³ versus 2.7 for aluminum and 7.8 for cast iron; the ability to operate for a long time at temperatures up to 260 °C without loss of characteristics; as well as a low coefficient of friction and pronounced antifriction properties.
For Holtzberg, this was a chance. As a basis, he chose a simple and proven architecture - the Ford 2.3 Lima four-cylinder engine, deciding to replace almost everything possible with composites.
What the "Plastic" Engine Consisted Of
The list of parts made of Torlon-based composites still sounds almost implausible today. The cylinder block, cylinder head, valve cover, and oil pan were made of plastic. Connecting rods, piston pins, and even piston skirts turned out to be in a composite design. The same included the timing gears, valve spring retainers, and rocker arms.
Of course, the engine was not completely plastic. The most loaded and thermally critical elements remained metal. Thin cast-iron sleeves were pressed into the composite cylinder block, and the combustion chambers in the cylinder head were made in the form of metal inserts. The crankshaft and camshaft, valves, and piston crowns were also made of steel. However, everything else was indeed made of plastic.
Why was such a radical design needed? The main argument was weight. A fully assembled Polimotor weighed only 68 kilograms. For comparison, the cast-iron Ford Lima weighed approximately 205 kilograms. Saving almost 140 kg on the engine alone looked revolutionary. An additional advantage was low noise: the plastic effectively dampened vibrations. In addition, the lightweight piston group significantly reduced inertial loads, allowing the engine to rev faster and easier.
Racing Test
Such a daring project could not go unnoticed. Ford became interested in the idea, seeing real potential in it. As a result, the project received support and went beyond laboratory experiments.
To prove the viability of the concept, the engine was decided to be tested in the most severe conditions - in endurance races. The Polimotor was installed on the Lola T616 racing prototype. In 1984 and 1985, the car participated in the IMSA GT championship. The car not only started but also finished, including such legendary marathons as the "24 Hours of Daytona" and the "12 Hours of Sebring."
There were no victories, but the very fact that an engine, mostly made of plastic, withstood daily races became a real sensation and proof of the idea's operability.
Why the Revolution Never Happened
Despite its successes, the project gradually faded away. The reasons turned out to be fundamental. First, the price: Torlon at that time cost astronomically expensive, and the cost of one engine made mass production economically meaningless. Second, heat dissipation. Metals, especially aluminum, effectively distribute and dissipate heat, while plastic is a good insulator. As a result, heat concentrated in the hottest areas, causing local overheating, deformation, and destruction of the composite structure.
The complexity of production also played a role. The technology for manufacturing precise and complex parts from thermosetting composites was in its infancy, and the percentage of defects was too high. Finally, by the mid-1980s, the oil crisis was over, gasoline became cheaper again, and the need for ultralight engines lost its urgency.
Second Attempt
The story could have ended there, but Matti Holtzberg did not give up on his idea. Decades later, he announced the Polimotor 2 project - a new version of the plastic engine, developed using modern technologies. We are talking about more affordable and heat-resistant composites, as well as the use of 3D printing in the creation of prototypes and molds. The goal remains the same: to install the engine in a modern sports car and once again prove the viability of the concept.
The story of the plastic engine is not a story about failure. This is an example of a project that was decades ahead of its time. It showed that the impossible can work and became an important step towards the widespread use of composite materials in automotive engineering. And, perhaps, thanks to such obsessed enthusiasts as Matti Holtzberg, one day a serial car will indeed have an engine under the hood that can be lifted with one hand.