Ro­tary could res­ur­rect RX-7

Herald Sun - Motoring - - Prestige -

A RO­TARY en­gine that uses half the fuel of its pre­de­ces­sor could be the key to the re­turn of a Mazda RX-7 sports car.

The petrol-pow­ered ro­tary is promised within three years as Mazda — the only com­pany to make a long-term com­mit­ment to the ro­tary de­sign — works on three projects for the pow­er­plant.

Apart from the over­haul of the en­gine now used in the RX-8, Mazda is de­vel­op­ing a ro­tary that runs on hy­dro­gen and an­other that pow­ers an on­board generator to drive the car — in a sim­i­lar way to the Chevro­let Volt — through elec­tric mo­tors.

The petrol ro­tary is for a two-seater coupe ex­pected in three or four years. Though Mazda isn’t say­ing any­thing about the car, it’s an open se­cret that it is work­ing on a re­vival of the RX-7 which was its sports car head­liner for more than 20 years. Mazda’s se­nior pro­gram di­rec­tor of re­search and devel­op­ment, Seita Kanai, says Mazda is not go­ing to aban­don the ro­tary.

Pow­er­train Devel­op­ment Di­vi­sion head Mit­suo Hit­omi says the same prin­ci­ples that make the Sky-G en­gine se­ries more fuel-ef­fi­cient and torquier are be­ing ap­plied to the ro­tary.

‘‘This in­cludes mak­ing the en­gine a long-stroke,’’ he says.

‘‘You can do that with a ro­tary — but of course it’s a dif­fer­ent tech­nique to an ICE (in­ter­nal com­bus­tion en­gine). The spark plug area . . . can be changed con­sid­er­ably.

‘‘The ro­tors can also be made slim­mer, which is part of chang­ing the com­pres­sion ra­tio.

‘‘Then you can also re­move a lot of weight in and around the en­gine.’’

Ro­tary plat­form? Mazda re­cently re­vealed its sleek Shi­nari con­cept.

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