Michael Arsenaeu designed the Avadi engine 20 years ago with the hope of creating a completely new, efficient and lower-emission engine design. In 2015, Avadi began construction and development of its engine.
He could have called it a rotary engine, but Felix Wankel beat him to it. It eliminates half the guts of a traditional engine, using a fascinating arrangement of rotating piston and sleeve internal. This makes it simpler, lighter and more efficient. And they claim that it generates a lot of power and torque.
The design uses a piston with two connecting rods, with a scissor-like motion attached to pinion gears at the rear of the engine. All of this rotates on a fixed ring gear connected directly to the output shaft. It uses a valve disc, which also rotates, to complete a four-stroke cycle of intake, compression, combustion and exhaust… all while rotating internally. To understand it, it is certainly best to see it in operation:
Unlike a Wankel rotary engine, the Avadi does away with the traditional crankshaft altogether, as the cylinder and piston rotate inside the casing during its stroke. Its operation is reminiscent of a rear differential, if it had pistons connected to planetary gears, of course.
Avadi showed a prototype of the MA-250 engine, which weighs just 10.7 kg and delivers 11.8 kW at 3700 rpm and 30.24 Nm. Compared to a motorcycle of that capacity, it is about three times lighter and has better performance, and it also eliminates the gearbox. As for thermal efficiency, Avadi claims it is 42.12%. Toyota’s four-cylinder engines are around 39%, which is an excellent figure.
All these numbers seem to indicate that it has a long way to go… but Avadi presented it in January 2022 at CES… and since then there has been no news, beyond a change in its technology director and a replacement of the rotary valve to solve problems that they were going to test in a new prototype at the end of 2023.
We now read that that revised engine is progressing well and they have achieved positive compression results with a new valve design. Could it work, in a world moving towards electrification, as a range extender, a solution that the Mazda MX-30 employs? That efficiency and, above all, its low weight, make it suitable.
