The fast, the furious, and the tasteful.
The main difference between rotary and your more standard combustion engines is that rotary engines don't use pistons. Essentially, one or more triangular rotors spin in a circular chamber to combust the fuel/air mixture, which is a lot less complex of a solution than using pistons. Other advantages include less mechanical stress, less vibration, higher power-to-weight ratio than a piston engine, higher compression, the ability to use a wider range of fuels, a wider torque band, and better thermodynamic efficiency.
It all sounds wonderful when described as above, but the only successful rotary engine design to be used in cars is the Wankel, most famously found in the Mazda RX-7 and RX-8. The problems come with fuel efficiency and emissions and the habit of the rotary seals to fail as they are exposed to the fuel and varying heat levels. They also tend to consume a lot of oil. However, when the pros outweigh the cons, it can be a brilliant engine. It's also a great candidate for engine swaps to give a car a completely different character in its performance. Engine swaps are not the easiest of projects, and a rotary has a particularly high level of difficulty, but that hasn't stopped some adventurous car owners.
There are a couple of standard options for taking the original Beetle from being a car that plods along to a car that can blow modern cars away from the lights. If you have the money, a Porsche flat six-cylinder is the obvious choice. Otherwise, a Subaru flat-four is an excellent choice. However, Mario Markakis opted for a 1.3-liter 13B engine from a second-generation RX-7. Because the engine itself is small compared to the four-cylinder lump, he managed to squeeze the stock turbo and intercooler in the back so he could get the full 250 horsepower. Because the Beetle is light, this one is now a 10.5-second quarter mile car.
If you're going to swap out the V10 engine from BMW's E63 M6, an LS just isn't going to hit the spot. Instead, the South African tuning shop AJ Racing swapped the 500 horsepower V10 for a custom-built six-rotor rotary engine. For reference sake, Mazda's insanely fast R26B race engine was custom built using four rotors. A six-rotor engine is a rarity. In this case, the engine showed 478 hp on the dyno while revving to 5,500 rpm, which is just starting to get into its powerband. Other KiwiRE built rotary engines have demonstrated 800 hp and up. If you want to know what a six-rotor engine sounds like, it's well worth checking out the video below.
One of the great wonders of the off-road world is Suzuki's little Samurai. Despite feeling like you're a pea in a tin whistle inside one, and that it was powered by a 1.3-liter engine making around 60 hp, those little suckers seemed to be able to go anywhere. This one is swapped with what looks like a Mazda 12A rotary from the first-generation RX-7. It made around 100 hp when new.
It also looks suspiciously like a Holly Double Pumper carburetor mounted on the engine. It popped up for sale on Craigslist last year, where it was residing in the desert city of Hesperia, California. It's a build someone has put a lot of time into and looks amazing, so hopefully, someone bought it and is still ripping it around dirt trails in California.
An engine swap doesn't have to be about adding more power, but like the Samurai above, the Mazda 12A rotary replacing the original 1.2-liter four-cylinder will have doubled the power to close to 100 hp. In the RX-7, the 12A propelled it to 62 mph in 9.2 seconds, but the vintage little Mazda 1200 was a lighter car. The engine upgrade won't have turned this 1200 into a rocket ship, but it will make the stylish little coupe much more drivable in modern traffic while giving it even more character - which is exactly what a restomod should be about.
There are plenty of RX-7's out there with V8 swaps, but you'll find very few muscle cars with the V8 swapped for a rotary. Nick Holms of Houston, Texas was up for the challenge, though, and built something not just unorthodox, but when you hear it rev out, something mind-bending. The orange 1974 Chevy Nova is now home to an extensively modified turbocharged 13B Mazda rotary boosted to 26 lbs of forced induction and making 576 hp and 449 lb-ft of torque at the wheels. That's a lot more beef under the hood than the original factory-installed 350-cubic inch V8 that made 185 hp, and is good for an 11-second quarter-mile time.
Even more baffling for traditionalists than the Nova swap is the idea of swapping the V8 from a C5 generation Z06 Corvette for a Mazda rotary engine. YouTuber Rob Dahm is becoming famous for his rotary swaps, but so far, this is his finest effort so far. The engine is stock, but the two-rotor 13B's turbo is swapped out for a Garrett GTX3584RS turbocharger, and the brain of the engine is now an Adaptronic M2000 ECU. Its first run on a dyno with a tune showed 550 hp and 503 lb-ft of torque, which is 145 more horsepower and 104 more lb-ft of torque than the factory LS1 installed under the hood.
Dahm's next project is to put a crashed C8 Corvette he bought back on the road with rotary replacing the 6.2-liter LT2 V8.
This is an old one, but it's also, literally, a gold one. Queen St is a renowned Australian show car building company that turned its hand to drag racing with exquisite style. The Queen St BMW E46 M3 turns everything about drag racing on its head, first by using an E46 generation BMW M3, then by using a four-rotor 1,600 hp Mazda rotary engine. And, just in case that wasn't statement enough, Queen St went ahead and took the gold and black color scheme to the extreme by 24-carat gold-plating the PAC Performance built engine. The last we heard was that the drag car had a personal best quarter-mile time of 6.827 seconds and, below, you can see and hear it in all its glory and, thankfully, not see it crash.