How two-stroke engines nearly changed the game

This is Pininfarina’s striking Ethos concept, a space-age Mazda MX-5 rival

We explore how two-stroke fever swept the West and threatened to revolutionise engine technology

With an all-electric automotive future now looking rather less of a shoo-in than it once did, some car makers are contemplating the next iteration of the internal combustion engine by developing versions powered by hydrogen or synthetic e-fuels.

But rather than change what you’re burning, what if you changed altogether how you burn it? That’s exactly what Ford had a crack at in July 1992, when two-stroke fever swept the West and threatened to revolutionise engine technology.

Two-stroke engines had a poor reputation by the ’90s. Most people could barely remember that the Saab 96 had started out with such an engine before swapping to a V4, but some — hailing from east of the Iron Curtain — carried generational trauma from Trabants and Wartburgs.

They were perceived as too fragile, too peaky in their power delivery and, crucially, much too smoky to ever meet an emissions standard, rudimentary as they were at the time.

But in 1991, the Orbital Engine Company thought it had it licked. It took founder Ralph Sarich’s Orbital powerplant design (think a Wankel but with a central ‘piston’ orbiting the centre of the combustion chamber, rather than rotating around its edge) and adapted it into a two-stroke piston design. “Immediately we got good results,” Sarich told us that January.

The Australian firm settled on a 1.2-litre three-cylinder design that was smaller than an equivalent overhead-valve four-stroke, £100 cheaper to produce and more powerful to boot.

Ford was moved by the prospect, inking a licence agreement in 1986. Five years later, Orbital had readied a fleet of Fiestas fitted with its engine, kicking out 80bhp and 90lb ft — a marked jump from the 60bhp and 73lb ft of Ford’s 1.3-litre Kent unit.

We tried an early prototype in the US and determined it was “an engine whose time had come”. We were impressed by its flexibility — “second-gear starts are smooth and brisk; even third’s not sadistic” — and duality of character, it making easy progress at a cruise and then singing when pushed hard.

We had another go in July 1992, this time on home turf. Again, “the most welcome thing is this engine’s flexibility”, our correspondent said. They noted that “there is no telltale smoke”, hinting at the work that had been done to cut the two-stroke’s emissions.

As well as the Fiesta, Ford planned to throw the two-stroke into a sports car.

Three weeks after testing the supermini, we drove Pininfarina’s striking Ethos concept, a space-age Mazda MX-5 rival. It checked many boxes a good roadster ought to: precise, communicative steering, a low roll centre and a satisfying balance between slip and grip. A light engine tune, boosting power to 94bhp, made it both “brawny” and “zesty”.

The Ethos II coupé followed a year later, now meeting California’s ultra-low-emission vehicle standard. It was just as much fun to drive, but one sticking point had become clear.

“Until the two-stroke engine is either proved to be a suitable power source or discredited completely, the Ethos twins are likely to remain concepts,” we said.

Despite licensing agreements with Fiat, General Motors and Volkswagen, and links with Honda and Toyota, the dominoes quickly began to fall. VW was first to go, confirming it had cancelled its deal at the 1993 Frankfurt motor show.

The death knell was Ford’s abandonment, confirmed in August 1994. It had been due to use the two-stroke powerplant in the Ka but it failed to meet “the confidence level Ford requires”. Insiders suggest it simply wasn’t durable enough, so Ford stuck with the trusty old Kent.

Fiat thought about putting it in the rival Cinquecento, benchmarking it against a 16-valve development of its four-stroke Fully Integrated Robotised Engine. “In the end we went with the four-valve Fire on the basis of its superior fuel consumption and emissions,” said Fiat engineer Dario Sacco.

Orbital tried to revive interest in the powerplant in 1995, when it launched a modified Ford Festiva (also known as the Kia Pride or Mazda 121) that packed a revised 1.2-litre powerplant. Some 100 were built and given the ‘Ecosport’ moniker, but it was a failure.

The two-stroke reappeared in the 1998 xAccess concept but it amounted to nothing concrete and the engine disappeared thereafter. The Orbital Engine Company is called the Orbital Corporation today, building propulsion systems for unmanned aerial vehicles.

But with major manufacturers re-evaluating combustion engines in their entirety, could the Orbital two-stroke rise again? Something’s certainly afoot: in March, Japanese firm Mitsui E&S successfully ran a two-stroke marine engine on hydrogen gas. Watch this space.