When it comes to iconic engines used in iconic cars, it’s pretty hard to beat the rotary engine. Sure, in totally stock form, something like a Mazda 13B is not particularly interesting, exciting, or special. But, with some magic, these little engines can not only sound incredible, but they can pack a serious punch.
Unfortunately, though, the rotary design has some drawbacks, which is part of the reason that Mazda stopped using it quite a while ago. And while just about all of us thought it was the end of production rotary engines for road cars, Mazda is actually bringing it back for 2023. The question, though, is why?
Why Mazda Used the Wankel Engine Previously
To preface this, I think it’s worth mentioning the fact that rotary engines work entirely differently than standard internal combustion engines with pistons and a crankshaft. It was around the late 1700s that we saw the development of the first internal combustion engines, but it wasn’t until over 150 years later that we saw the invention of the rotary engine.
And that should give you an idea of just how different the rotary engine is. And we’re not going to get deep into the specifics of how a rotary engine works in this video, because, well, that’s already been explained by much smarter people in other YouTube videos.
But, to highlight some of the benefits of the rotary engine, it’s incredibly small and compact compared to a piston engine, and for a single rotor, there is really always a combustion stroke happening. And because of the small physical size of this engine, it’s also pretty lightweight.
Part of it being physically small is simply from Mazda never developing a rotary with a big displacement. Instead, the most popular rotary engines found in their products have displacements of 1.3L or 2.0L for their road-going cars.
And yes, there are other displacements out of the rotary engine. From 0.4L all the way up to 2.6L, there are a handful of variations out there, but the engine that is most popular on the internet for its use in Mazda’s 1990s sports car, the RX7, comes as a 1.3L, known as the 13B.
There’s also the 20B that you can find in the Eunos Cosmo, which is a 2.0L rather than a 1.3L, but rather than taking the exact design of the 13B, which was a 2-rotor engine and scaling it up, Mazda instead chose the route of adding a third rotor.
And where it gets really crazy is with the 26B engine that was used in the 767 and 787B Mazda race cars. In fact, the 787B was the first car ever to win the 24 Hours of Le Mans race outright without using a piston engine.
So, we know this engine is small, decently powerful, capable of winning at the highest level of racing in the world, and pretty lightweight. So, why did Mazda stop using it? Well, there are a few drawbacks to this design.
Most notably, fuel efficiency isn’t particularly great, the emissions output is surprisingly bad, oil consumption is way too high, and the overall lifespan of the engine is significantly worse than the average piston engine.
With that info in mind, it kind of makes sense why Mazda stopped offering this engine because it simply didn’t have enough pros to outweigh the cons. Which brings us to the real question, with all this in mind, why did they bring the rotary back for 2023?
Well, there are two answers to that question. For one, they fixed some of the problems related to fuel efficiency and emissions output, and two, the rotary they’re bringing back for 2023 isn’t actually powering the vehicle.
Mazda Brings it Back…. as a Generator
And by now, you’re probably thinking, “ok, this guy is definitely an idiot. How on earth is Mazda using this engine in a car, and you’re sitting here saying it’s not powering the car?” Well, that’s because this new rotary engine in the upcoming 2023 MX30 isn’t directly connected to the wheels at all.
Rather, they’re using this engine as a generator for the electric system, which is obviously comprised of electric motors and a battery system. That’s right; they did all of this just to use it as a generator, which is kind of disappointing.
But why even bother then if it’s just a generator? Well, according to Mazda, the whole purpose of using a rotary as a generator compared to a piston engine is that the engine is more compact, and while that kind of kind sounds like a marketing gimmick at first, it’s accurate to say this engine has a ton of output relative to it’s small size.
But that being said, there are plenty of small gas piston engines that Mazda could’ve used that would’ve worked just as well or better. So, yes, it’s a little bit of a marketing gimmick, but their job is to sell cars, so you can’t really blame them.
As compared to their previous rotary engines, particularly their last production rotary found in the Mazda RX8, this new engine is much smaller and frankly more boring. It’s down on rotors, displacement, power, RPM, displacement per rotor, and basically anything that has to do with performance.
Mazda’s previous engines were multi-rotor units that revved very high and delivered lots of power and performance, particularly delivering lots of high RPM horsepower but severely lacking low-end torque.
And because this new engine is being used as a generator, the only thing that really matters is its efficiency at generating electric power while using as little fuel as possible.
Innovations and Upgrades
The biggest and most arguably most important upgrade to this new engine comes in the form of direct injection. This is a pretty big upgrade on fuel atomization and more. I won’t go into the nitty gritty details on why direct injection is so great, but just trust me, it’s a great upgrade for this engine.
Other interesting upgrades for this new little rotary generator include aluminum side housings which should even further improve the weight savings of the rotary design, especially considering how big the side housings are.
One of the oldest and most notorious problems with the rotary design is the apex seals, which I’m sure you’ve heard about online. But these little seals sit at the apex of the spinning Dorito and keep everything sealed.
For this new engine, they widened the seals by about 25% for improved wear resistance, which should massively help with engine longevity.
Mazda also has a crazy patent for using an electric motor to assist the rotary engine to either slow the engine’s rotation or speed it up and replicate some of the benefits of a variable valve timing system, which rotary engines can’t benefit from in a traditional context because they don’t use valves in the first place.
I won’t go into crazy detail on this patent from Mazda, as Engineering Explained has already done an amazing job at that over on his channel and explains it in far better detail than I could ever hope to, so I’ll leave his video linked in the description if you’re interested in checking out their crazy patent for rotary engines.
With all this in mind, it takes me to the biggest elephant in the room with this engine, which is the fact that as of right now, we’re not even getting it here in the states. Instead, this is a strictly European product for now.
But, the hope is that with this new and improved rotary engine, we could see this design used in Mazda’s long overdue RX9 sports car if they ever decide to release that.
In the meantime though, all we can do is wait to see if they continue to bring the rotary back or abandon it for a second time.
What is my opinion on this? Well, I definitely think it’s interesting that they’re using a rotary again, but in the context of a simple range extender for an otherwise boring SUV, I must say, it’s disappointing.
Not only that, but frankly, I think it’s not a great move. It allows them to leverage marketing on the few things that have ever helped them stand out as a company, but otherwise, it probably would’ve been easier to use a standard piston engine for this application. Plus, they likely could’ve delivered an even more efficient product with a standard piston engine.