Mazda's rotary engine is back, though it's not exactly what everyone wanted. Unlike its previous applications, the returning Wankel rotary mill isn't utilised in a sports car application. In fact, it's used differently from before but with various notable improvements. Jason Fenske from Engineering Explained on YouTube gives us a deep dive into the new rotary engine and how it differs from its predecessor.

The rotary engine in the new Mazda MX-30 R-EV features a single-rotor rotary engine. The new power plant revs lower and less powerful compared to the previous one found in the RX-8, which used a dual-rotor rotary engine.

However, Mazda has employed some clever tricks in this new engine. Fenske said that one of the most notable changes is that fuel is now directly injected into the combustion chamber, which helps to keep the fuel in the main area of the chamber and improve atomisation. The Japanese automaker has also introduced the use of exhaust gas recirculation this time, which helps with efficiency at low loads and low RPMs by containing some of the heat within the engine.

In addition, Mazda is now using aluminium side housings instead of iron, which is good for weight savings, and a spray-on plasma ceramic coating that improves wear and friction. The wider apex seals up to 2.5 millimetres, a 25 percent increase, giving better wear resistance.

Of course, the big kicker and the disappointing news is that the engine is simply used as a range extender. The engine spins up a generator that provides power to be stored in a battery or to an inverter which then powers an electric motor that drives the vehicle. There is no direct link between the engine and the driven wheels.

Fenske also discussed how Mazda came up with a clever solution for the variable valve timing problems connected to rotary engines by using a high-pressure fuel pump. The video atop this page should explain that further.