Discovered by Road and Track, the petrol and diesel engine filings were made in January with the US Patent and Trademark Office, but only officially published this month. Both American applications are based on patents, yet to be granted, filed in Japan in February 2016.
For these engines, the electric supercharger used at low engine speeds to improve responsiveness, with the turbochargers only kicking in at higher revs. No word, yet, on how much power this engine might produce, nor how much fuel it will consume.
The engines in the filings are shown in a rear-wheel drive configuration. This hints at a possible future MX-5 variant, although given Mazda's firm stance on the vehicle being about driving enjoyment rather than out-and-out performance, this seems unlikely.
It could also point to a power plant for a new rear-wheel drive sports car, luxury sedan or SUV. As with many patent filings, development work on this engine may lead to a dead end with no production result.
In 2014, Volvo unveiled a 2.0-litre "triple boost" four-cylinder engine with an electric compressor feeding into a pair of parallel turbochargers. Volvo's 336kW engine has yet to be put used in a production vehicle, although it has already been demonstrated to the media.
Last week, Mazda announced plans to put a compression-ignition petrol engine into production by 2019. Dubbed SkyActiv-X, the new motor has a supercharger. It uses spark plugs when the engine is cold or being worked hard, and compression ignition at other times.
As part of its recently upgraded partnership with Toyota, Mazda will continue to develop internal combustion engines, while also leaning on its bigger partner for help with hybrid and electric vehicle technology.