The piston engine may be the most common type of internal combustion engine found in consumer automotive vehicles. That doesn’t mean it’s the only option drivers have ever had access to. In the 1960s, the rotary engine made its first appearance in a vehicle. Mazda in particular embraced the innovation, installing rotary engines in vehicles like the Mazda RX-7. However, while Mazda may have recognized the pros of this alternative engine, the cons of rotary engines are also important to be aware of, should this engine type ever make a comeback.
The technical differences between rotary engines and piston engines are significant. Ultimately, though, they serve the same purpose: generating power for a vehicle. Rotary engines generate and supply this power via the spinning of its rotor, while piston engines (as you likely guessed) rely on the up-and-down movements of pistons to do so.
It’s worth noting that most automakers have stopped using rotary engines. Thus, your options for purchasing a car with such a powerplant may be limited. That said, because it’s technically possible that you may have the chance of investing in such a vehicle one day, you should familiarize yourself with the advantages and disadvantages a rotary engine offers. Equipping yourself with this knowledge is key to making an informed purchase.
Pro: Rotary engines are simpler and smaller than piston engines
A typical rotary engine will usually be smaller than an equivalent piston engine. It will also consist of fewer moving parts. These two factors potentially yield multiple advantages for drivers.
Because a rotary engine is smaller than a piston engine, it contributes less to a vehicle’s overall weight. The result could be greater agility when driving. Rotary engines are particularly well-known for their ability to generate substantial horsepower relative to their size.
Fewer parts can also guard against sudden engine failure. The more parts an engine consists of, the more opportunities there are for a part to fail. Depending on the specific nature of the failure, this could cause damage to the rest of the engine, or perhaps even other internal components of the vehicle. This is generally less likely to be an issue with a rotary engine. Instead of dying without warning, a rotary engine may signal its failure by slowly generating less power than it normally does, giving a motorist more time to identify and address the problem.
Con: Rotary engines consume larger quantities of oil than piston engines
Both rotary engines and piston engines require oil to keep their parts lubricated while in operation. However, they differ in regard to what ultimately happens to the oil they use. For example, in a piston engine, oil can sometimes splash onto the cylinder walls. When they’re working properly and haven’t been worn-down, piston rings help scrape the oil back down so it doesn’t make its way into the combustion chamber, where it can burn.
Rotary engines work differently. Specifically, a rotary engine will allow some oil to enter the engine housing chambers. Again, this is to ensure lubrication. Unfortunately, it can also result in rotary engines using up more oil than their piston engine counterparts would in the long run.
High maintenance needs represent one of the key disadvantages of a rotary engine. This point highlights just one example of such needs. If you drive a vehicle with a rotary engine, you’ll need to be comfortable with checking and replenishing the oil more often than you otherwise would.
Pro: A rotary engine may deliver a more pleasurable driving experience
Several qualities of rotary engines may appeal to auto enthusiasts seeking a specific type of driving experience behind the wheel. Because the design of a rotary engine is meant to optimize balanced performance, driving a vehicle with such an engine can involve less vibration and smoother revving than you might experience when operating a piston engine vehicle. Again, the small size and weight of a rotary engine also allow for an improved center of gravity, which can further enhance the smooth feeling of driving a car with a rotary engine.
The sound a rotary engine makes also differs from a piston engine’s sound. Because the engine fundamentally works differently from more traditional automotive engines, it naturally generates a unique engine note when in operation. Some motorists find they appreciate this quality enough to consider it a noteworthy advantage of rotary engines. That said, this is certainly a matter in which subjective opinion plays a role. It’s unreasonable to say that all drivers will prefer a rotary engine’s sound when compared to a piston engine.
Con: Rotary engines aren’t ideal for the environment
Once more, a rotary engine burns oil. It’s designed to. As we’ve already covered, this adds to such an engine’s overall upkeep requirements. Sadly, that’s not the only downside associated with this aspect of rotary engines.
Burning oil naturally sends contaminants into the environment via the tailpipe. Add to this the fact that rotary engines tend to be less fuel efficient than piston engines, and you may understand why rotary engines can struggle to meet emissions standards.
Not meeting strict emissions standards is one reason these types of engines aren’t very common. Even if you find a vehicle with a rotary engine, if you’re an eco-conscious consumer, you might opt for something that’s less harmful. On top of accounting for the damage a rotary engine can do to the environment, you may also consider how its fuel and oil usage could lead to high long-term ownership costs.
Just remember, to some degree, this may all be a moot point. Rotary engines are virtually unheard of in today’s cars. That said, a new Mazda patent indicates an improved rotary engine may be on the way. If buying a vehicle with a rotary engine becomes a mainstream option again in the future, you’ll benefit from knowing the reasons you should or should not consider making such a purchase.
