Northampton-based Ilmor Engineering, which builds motorsport engines for Formula 1 and IndyCar racing, developed the technology for a General Aviation diesel engine as part of an EU Clean Sky 2 project, funded by the Horizon 2020 programme.
The project’s aim was to improve the power density of the engine by increasing power and reducing weight, while also maintaining fuel efficiency, according to David Robertson, design engineer at Ilmor Engineering.
The company worked alongside SMA, the piston engine division of Safran Aircraft Engines, which supplied the 227hp, four-cylinder, four-stroke, horizontally-opposed engine, typically used in Cessna 182 aircraft.
By replacing the engine’s iron liners, within which the piston runs up and down, with a plasma bore coating, Ilmor was able to reduce the overall mass by 2.6 per cent, said Robertson.
“We basically replaced the iron with aluminium, which removed a substantial amount of weight,” he said.
However, while iron is a very good material to use for surfaces that interface with a moving piston, aluminium is not, so the new liners needed careful treatment, he said.
“We used a company in Switzerland who heat up powder, in this case an iron-based mix, and blast it at the surface, where it coats the surface in a very thin layer of iron,” he said.
This process creates a very similar surface to a heavy iron liner, but with a much reduced weight, he said.
The team designed new components and redesigned existing ones, such as the crankcases, cylinder heads and cylinder barrels, in order to meet the increased demand on the engine from the greater power density.
The re-designed engine parts were manufactured by Ilmor, then assembled by SMA and run for just under 100 hours on a test bench in France, which demonstrated its increased power and reliability.
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