In several decades past, a new weird little engine showed so much promise. The Wankel rotary, an internal combustion engine that promised high power-to-weight ratios and greater reliability without pistons, was seen as the future. Countless world automakers made rotary engines, with most figuring out the promise wasn’t reality. But before the popularity of the Wankel died, a slew of automakers, including Daimler, John Deere, and Rolls-Royce, took the weird tech to its limit by trying to make hyper-efficient diesel engines out of rotaries. But there’s a reason why you can’t drive a rotary diesel truck today.
If there were ever an engine worthy of being called “cursed” it might be the rotary engine. Almost every single company that has experimented with Felix Wankel’s oddball engine has failed to really make anything worthwhile out of it. Somehow, Mazda made rotaries briefly work, but it has even reduced its once main obsession with rotary technology to a side project.
This is because the rotary is among the list of engines that seemingly worked better in concept than in real life. But that never stopped some of the greatest automotive minds of the 1960s and the 1970s from trying to make rotary power the future. In the 1960s, German diesel engine manufacturers Daimler-Benz, KHD, Krupp, and MAN joined forces to make a diesel Wankel. At the same time, Rolls-Royce might have created the weirdest rotary in history when it also tried to make the fabled engine design drink diesel fuel. Then, John Deere took a crack at it, too. Take a look at John Deere’s glorious 11.7-liter rotary:
The Wankel Promise
It’s sort of amazing that the rotary engine even exists in the first place. But its history also has a tinge of darkness. All of it revolves around the rotary’s inventor, one Felix Wankel. Here’s a quick reminder of how the rotary came to be, from some of my previous work:
German engineer Dr. Felix Wankel is credited with coming up with the idea for the rotary, also known as the Wankel engine, in around 1919 when he was just 17 years old. Wankel started building prototypes years later and finally earned a patent in 1929. Wankel’s development then slowed until he joined the Nazi Party and its Aeronautical Research Establishment during World War II. There Wankel would continue his work on his engine. Reportedly, the Nazis believed Wankel’s engine could give them an advantage in the war. Later, he’d arrive at NSU Motorenwork AG. By 1957 the rotary was no longer just a proof of concept but Wankel had running prototypes. Felix and NSU earned more patents and were quick to license out the technology.
Wankel is the inventor of the rotary gasoline engine, but the idea of the rotary sprouted up hundreds of years before him. Ramelli invented a rotary-piston-type water pump in 1588 while James Watt had a rotary steam engine in 1769. Though, it’s perhaps notable that neither of those earlier designs resemble the spinning triangles of the Wankel.
In theory, rotary engines have a lot going for them. Wankel engines have fewer moving parts than an equivalent piston engine.
Their design also allows them to take up less space than an equivalent piston engine. Yet, because a rotary completes three full Otto cycles (intake, compression, combustion, exhaust) per rotation, a little 300cc rotary could produce the kind of power a piston engine of double the displacement puts out. Further, Wankel engines are nearly turbine engine-smooth with a broad rev range.
All of the promises noted in the paragraph above proved to be alluring to automakers all around the world. On paper, the rotary was practically magic and NSU was quick to license the technology to anyone bold enough to try to make something out of it. Honestly, it’s incredible how many companies put Wankels in different vehicles.
Hercules, Motorrad Zschopau, Norton, Suzuki, and Van Veen each dropped rotary engines into motorcycles. The Suzuki and Norton efforts were especially notable as both of these companies dumped tons of money and development time into attempting to correct the rotary’s problem with running sizzling hot and wearing out its apex seals. Both companies eventually failed to make rotaries last in the long run.
Rotary development in cars, trucks, and military vehicles was frankly insane. General Motors took on a rotary license and originally saw rotary power in everything from the Vega to something sporty that was pretty much a mid-engine Corvette. The non-exhaustive list of other rotary developments includes efforts from AMC, Citroën, Daimler-Benz, Ingersoll-Rand, Outboard Marine Corporation, Honda, Kawasaki, AvtoVAZ, Ford, Curtiss-Wright, Savkel, VEB, Midwest Engines, and Yamaha.
Of course, the most famous use of rotary power is from Mazda. The automaker, which embarked on its own journey to perfect rotary technology as a way to make it stand out compared to the rest of Japan’s automakers, went all-in. Mazda’s rotary efforts were so wacky that it was the only automaker to make a production rotary pickup truck and the only automaker to make a rotary bus. From my retrospective:
Mazda admits it went a bit crazy with rotaries in the 1970s, stating “Almost everything Mazda sold in North America featured the engine.” This was hilariously true. If you were an American car buyer in the 1970s, you could get the RX-2 economy car, the RX-3 micro pony car, the RX-4 family car, and the RX-7 all with Wankel power. And what Mazda rotary history would be complete without the historic Cosmo and the bonkers Mazda Parkway Rotary 26 transit bus? Mazda says that in 1972, it sold about 100,000 vehicles powered by a rotary engine in America. Mazda’s rotaries were so popular that by the time the 1970s were out, about half of every Mazda built had a rotary.
Unfortunately, all of these automakers found out the dark secret of the rotary, and it’s that it’s extremely hard to get a rotary to live up to the promise of the power of a big engine in a package half its size while still being reliable. It was also extremely hard – and in some cases, impossible – to get the rotary to match the fuel economy and emissions of piston engines. In 1977, General Motors was pretty frank about this when it reported to the New York Times that the engine failed to “demonstrate the potential for low emissions levels and fuel economy equal to those of current reciprocating piston engines.”
Yet, despite all of the wild rotary developments of the 1970s, the craziest rotaries actually come from the diesel world.
Germany’s Obscure Diesel Development
The collaboration with the least amount of surviving information about it was the so-called “Ring of Four” or the “Diesel-Ring.” As the book, Wankel auf dem Prüfstand by Ulrich Christoph Knapp notes, Daimler-Benz, KHD, Krupp, and MAN saw how diesel piston engines were taking over the heavy truck space. However, the promise of the rotary also seemed great. What if both engine types could be combined into one? The four manufacturers worked together through the 1960s to try to make this happen. However, the book notes that the companies gave up in 1969, concluding that the convex combustion chamber of a rotary did not permit the high compression ratios required to make a diesel operate.
This development is so obscure that I could not find any photos of it. Mercedes would also try fitting a gasoline rotary to a sports car, but ultimately, the failures of rotary power to live up to its promises would drive Mercedes toward fitting countless vehicles with piston diesel engines. But the Germans weren’t the only ones tweaking rotaries in the 1960s.
Rolls-Royce Invents A Crazy Rotary
Rolls-Royce also found itself enamored with the promise of rotary power, but wanted to take it a step further. What if it could create a smaller diesel rotary that produced the power of a bigger diesel engine? In 1970, an issue of Autocar noted that Rolls-Royce was just one of two British automakers that had an active license to make rotary engines and that the second manufacturer, Perkins, hadn’t done anything with its license.
Rolls fell into the same rotary trap as the rest of the world and believed it could make a small engine that was both big on power and on fuel economy. In 1964, Rolls-Royce decided it wanted to build a rotary engine that had about the performance of an opposed-piston two-cycle engine. However, for a twist, the Military Vehicles Engineering Establishment said that Wankel should be a diesel, or specifically a multi-fuel engine. Rolls wanted to sell this to the military, and having the engine run on nearly anything that burns would have been a plus.
Unfortunately, Rolls-Royce immediately ran into the same hurdle the Germans did. The typical Wankel is a terrible candidate for a diesel engine. Notably, Autocar noted that the rotary’s geometry makes it difficult to produce a high enough compression ratio. On top of this, the long and thin combustion chamber of a rotary has a high surface-to-volume ratio, leading to huge heat losses and poor combustion.
One solution considered by Rolls was just changing the geometry of the rotary until it sustained a high compression ratio. But this just made a huge engine – defeating the purpose of going with a rotary – that had even worse combustion, anyway. The solution was hilariously convoluted. Rolls-Royce figured the solution was through forced induction. Normally, this would be achieved through a blower or a turbocharger. However, since the rotary is already a positive-displacement engine, Rolls had a better solution. Its engine would essentially be a twin-rotor engine, but one rotor would more or less serve as a compressor for the other, smaller rotor.
From an old piece written by Jason Torchinsky:
The Wankel engine can work in place of a conventional supercharger or turbocharger to compress the air-fuel mixture because a rotary engine is inherently a positive-displacement machine—essentially, that means the intake chamber has a larger volume than the exhaust/discharge chamber, so the mixture within is compressed.
In the case of the Rolls-Royce Wankel Diesel, the fuel-air mixture is first compressed by the lower rotary, and the output of that engine (which would be like the exhaust valve of a conventional rotary) sends the compressed diesel/air mixture to the intake of the smaller upper rotary engine, where it’s compressed to ignite like a regular diesel engine.
The development wasn’t limited here. Rolls-Royce went through over 100 different combustion chamber shapes before landing on the sort of figure-eight design as being the optimal one. The Rolls crew also had to deal with the rotor tip seal failures that were so common with rotaries back then. But worse, they had to engineer the tip seals to be able to withstand diesel pressures. For that, Rolls-Royce switched from carbon for the tip seals to steel tip seals. Further, the seal springs had to be made out of Nimonic 90 nickel alloy. The engineering team further ran into issues with the rotor tip seals jamming and losing contact with the rotor housing. Rolls fixed these with leading edge slots and stepped apex seals, respectively.
Check out this explainer from our favorite YouTuber engineer:
The Rolls-Royce development team produced four prototype engines, not including the first NSU the team tested. From Autocar:
The first Rolls—Royce development engine was the R1 which was conceived purely as a research tool. With a compressor stage of 1,126 c.c., and a combustion stage of 500 c.c., it produced over 50 bhp and achieved specific fuel consumptions of better than O.5lb/bhp/hour. Among other things, it was used to develop the best inter—porting arrangement between the two stages.
The R2 engine was the alternative three-stage layout, built but not investigated in detail. R3 refers to a combustion stage only, which is being used as a basic unit to build up a range of engines; it has a displacement of 1,216 c.c., and has produced 180 bhp at 4,500 rpm under test conditions.
The remaining engine of which details may be given is the 2—R6. This is a military engine formed of two banks of a two—stage engine. Each high pressure (combustion) stage has a displacement of 1,265 c.c., and is fed by a low-pressure stage of 3,250 c.c. The design power is 350 bhp at 4,500 rpm, for a weight of 939lb-a spectacular power-to-weight ratio for a diesel.
That last engine, pictured at the top, should have made rather healthy power. Diesel pickup truck engines weren’t even making that kind of power well into the 2000s. But unlike a Cummins 5.9, the Rolls-Royce 2-R6 was ridiculously complicated. The paragraph above doesn’t really detail how crazy that engine was. By “two banks of a two-stage engine,” Autocar meant that this engine was essentially two complete twin-rotor diesel weirdos operating next to each other. It was a four-rotor engine, but only technically.
But also note how Autocar said “design power” there, not that the engine actually made that kind of power. Reportedly, by the time Rolls-Royce actually got the 2-R6 on a test stand it was a bit of a disaster. The test engine ballooned to 1,150 pounds, and in testing, it made just 180 HP. Even worse, it’s alleged that this engine may not have even run on diesel, but compressed air.
It was now the early 1970s, and Rolls-Royce decided to cancel the project. No official reason was given. Some books, like The Wankel Rotary Engine: A History by John Hege note that the military lost interest in having a compact tank. Wankel auf dem Prüfstand concludes that Rolls-Royce engineers must have run into the same problem that pretty much every single other manufacturer had, and it’s that getting a rotary to live up to its promises might have been impossible.
John Deere Gave Rotary A Try
Despite all of that, there’s still one more obscure diesel rotary effort out there, and it comes from John Deere of all firms. In 1983, John Deere bought the rights to the rotary engine that Curtiss-Wright was working on for airplanes. Deere, like so many brands before it, thought it could improve Wankel’s design into something it could sell. Specifically, it wanted to sell a rotary to the government for military applications.
The company followed this up by forming the John Deere Rotary Engine Division (REDIV), and its mission was to create a multi-fuel engine for the government. This was called the Stratified Charge Omnivorous Rotary Engine (SCORE), and while it has been described as a diesel, the truth is far weirder. The “Stratified Charge” part of this engine refers to how the engine uses a pair of injectors to fire fuel into the combustion chamber and then how it uses spark to ignite that fuel. Curiously, the spark here is also supposed to ignite diesel fuel.
John-Deere’s REDIV explains more in a delicious technical paper:
The SCORE series of stratified charge engines have all of the attributes of these homogeneous charge rotary engines plus multi-fuel capability and diesel-level fuel economy. The compact overall dimensions common to both homogeneous and stratified charge rotaries derives directly from the very high ratio of working volume to total envelope volume. The basic rotary geometry also insures complete dynamic balance at all speeds since the rotor center of gravity, which is also its geometric center, remains at a fixed distance from the axis of shaft rotation, even though the rotor is also rotating about its own center. Therefore, balancing, for any number of rotors, can be achieved by use of shaft-speed rotating counterweights. The resultant smoothness is more characteristic of gas turbine engines than of reciprocating engines.
In similar fashion to a two-stroke reciprocating engine, there is one power stroke per shaft revolution for each rotor, but this ported engine operates on a complete 4 stroke cycle for good volumetric efficiency through an unusually wide speed range. This range is a function of both the improved breathing capability of ports and the absence of speed-limiting valve dynamics. The direct injected stratified charge rotary, like a Diesel, operates unthrottled and, with the separate pilot nozzle (Fig. 1), can also be run at an extremely broad range of fuel/air ratios. Combustion is initiated by light-off of the pilot jet; the amount of fuel supplied to the pilot nozzle is less than 5% of the total full power flow and remains constant, per injection, throughout the operating range. The multi-hole main nozzle is located close to the trochoid surface. The power is controlled by the rack setting of the main injection nozzle pump plunger and, without the restraint to set fuel air metering close to stoichiometric mixture strengths, a
complete spectrum or power levels and speeds can be run at full air flow and without throttle losses. However, to burn the overall lean mixtures commensurate with best thermal efficiency, combustion has to be initiated in the localized pilot light-off zone, with fuel and air stratified to provide proper mixture strength at that point of combustion initiation. Here again, rotary geometry helps achieve the particular and difficult prerequisites of stratified charge operation.
To make a long technical paper short, REDIV figured out how to make a spark ignition engine act like a diesel engine so it could be the kind of multi-fuel goodness that the military loves. John Deere said its rotaries would run on gasoline, diesel, kerosene, JP5, JP8, ethanol, natural gas, bio gas, methane gas, and finally, propane. Basically, if it burned, John Deere’s rotaries probably would have run on it.
John Deere saw its engines going into road graders, generators, light aircraft, tanks, armored personnel carriers, or really anything else that required a small engine that was big on power. Of course, John Deere is also a tractor company, so it had to put a rotary in a tractor too. That prototype Mannheim 2950 MFWD tractor had a 1.3-liter twin-rotor SCORE engine that made around 100 HP, or about the same power that you got in the tractor’s largest engine. However, the twin-rotor was a tiny thing.
REDIV ended up creating a slew of different prototypes over eight years of development. In an early brochure, John Deere advertised two engine families. The SCORE II was a twin-rotor engine family featuring outputs ranging from 375 HP to 2,250 HP. The SCORE III family featured single-rotor engines good for as little as 80 HP to 320 HP. Reportedly, the 80 HP mill was a 0.7-liter engine. Apparently, the most successful test engine was the SCORE 580, which featured two huge 5.8-liter rotors stacked on top of each other that produced over 500 HP in testing.
Another Failure
Yet again, even John Deere ran into a wall. Reportedly, the REDIV team discovered that its rotaries weren’t particularly fuel-efficient. That part isn’t surprising as that’s pretty much what everyone figured out in the 1960s and the 1970s. But for their particular applications, John Deere also figured out that rotaries make the bulk of their power when they’re spinning fast, which might not be the best fit for a road grader or a tractor. Like other builders, John Deere also ran into issues with rotaries running very hot and producing high emissions.
I should also note that, despite headlines, the John Deere SCORE engines weren’t necessarily diesel engines. They were spark ignition engines that were able to run diesel. At any rate, in 1991, John Deere gave up and sold the rights to its project to Rotary Power International. That company continued where John Deere left off, adding even more displacement and turbochargers. Rotary Power International claimed that it was working on rotaries with as many as six rotors and 34.7 liters, plus as much power as 3,000 HP. Like the John Deere SCORE engines before them, they were also designed to run on pretty much any fuel. Only this time, they were supposed to go into power boats and similar marine products rather than tanks and tractors.
Yet, even Rotary Power International died off.
Amazingly, you can still find a handful of companies trying to make rotary engines run diesel today. However, it appears that the curse of the Wankel lives on. The vast majority of companies that have ever tried to make a rotary engine work have failed to do so. Everyone from General Motors to Rolls-Royce has tried to make rotaries work, and they all reached the same conclusion. That’s what makes these diesel rotaries even more fascinating. Yet, I’m still saddened that there isn’t even one of these diesels out there. As silly as they may have been, the engineering involved with these engines was fantastic.
kind of sad really, a Diesel Wankel would be cool, and could be called a dankel.
Weisel was right there…
Thank you very much for the fascinating and well-written article on such a joyously esoteric topic Mercedes! 🙂
I actually saw a rotary chainsaw last summer- it ran sorta
A rotary has a high surface to volume ratio, which is part of what leads to high heat losses. The other part is the long, thin shape of the combustion chamber stretches out the combustion duration because any flame needs to traverse a longer distance in closer proximity to relatively cold walls in order to consume as much of the air as possible, leading to higher temperatures and temperature gradients through much of the expansion stroke (and into the exhaust) than a comparable piston engine. The slower combustion speed also hurts the conversion of fuel energy into piston work, and the greater quenched area hurts the fuel combustion efficiency as well. Lots of downsides from an efficiency perspective!
(Reference – I used to work on thermodynamic engine cycles research at GM, and currently own 2 rotaries (3 if you count a spare on the engine stand))
Thank you for pointing that out and for the great explanation! I meant “high” then wrote “low,” anyway. Maybe I was reading something else while typing. I will send out a correction.
Edit: I also love how many of our readers are engineers with a similar interest in crazy engine technologies. 🙂
!! Did you ever see the GM Rotary actually running?
Nope, that was before my time by a few decades, but I did see some of the old pieces floating around as desk ornaments.
If you…uh…have any of those desk ornaments laying around, I happen to know a buyer. 😉
Make that two!
This is funny to see from GM, considering the lesson they got from Honda in tuning engines in the 70’s.
Disclaimer: I haven’t read Mercedes’ article yet, but I’m very excited to do so, because I love weird engines as much as I love weird cars, and I also happen to be a fan of small diesels (owned a VW TDI for 23 years) and Wankels too (never owned one of those yet).
SO: thanks Mercedes for scratching this particular itch. Lemme go make some coffee so I can give your work the proper focus it deserves. 🙂
You know when I made that joke about a rotary diesel the other day I was just kidding, right? It’s like you’re reading my thoughts… Or comments, which are basically the same thing.
Great write up!
Let AI chew on this. We may as well have it try to make the ultimate enthusiast engine.
That’s a Party Size Dorito right there.
Nice to see the call-out to LiquidPiston. I swear, they’ve been one year from delivering a huge innovation in combustion engines for 20+ years. Good jobs program for some House district in CT I guess.
Forgot to mention the model aircraft Wankel engines of the 1970s…
What puzzles me is that piston steam engines on locomotives had seals for moving parts, moved by super-heated steam at incredible pressures, and were so finely engineered that the seals hardly ever failed.
The big weakness with most of those engines were the bearings.
Yet no-one has solved the seal problem for Wankels….
A mate had a rotary Mazda in the early 1980s, generally happy with it as long as the seals were changed every year, which cost a packet.
Car was wrecked when he hit a stray horse, which went through the windscreen and landed up mainly in the front passenger seat and the back seat behind it.
He had a broken bone or two, but the cops kept on telling him how lucky he was because in such cases they usually found the driver kicked to death by the horse’s death throes….
I forgot about those weird little buggers, I think I even heard one once at a free flight event. Perfect dorito conditions, they’re fed premix and don’t run that long.
I put over 175k on an RX7 without any seal issues. I’m convinced the key to good seal life is to avoid high loads on the engine until it is warmed up, and to let it idle for maybe 30-45 seconds before turning it off. Basically the same way you would treat an early turbo motor.
The horse through the windshield sounds terrifying!
Rotary: An electric motor with pyromania.
Last night I drove alongside an old RX-7 still chugging along. It was in pretty shabby condition but still going. I remember wanting one of those when they were new, and many years later I bought an NA Miata, which to my eye looks bigger than the original RX-7. I was thinking it would be fun to transplant that engine into a Miata. Although that would result in less power and atrocious fuel economy – and a lot of blue smoke.
She said “Wankel”
A diesel rotary is the enthusiast engine to end all enthusiast engines. Put it in a brown wagon or van and they’ll get scooped up en masse once they’re 10 years old and heavily depreciated, then we’ll all blog about how they don’t make em like they used to.
This is so true!
That would have most of the commentariat wanking to a Wankel…
OK, I’ll show myself out…
Also – the Wankel shows up in interesting places.
Pumps, various industrial uses – not always as an engine, as noted.
My favorite is that there are/were some seatbelt pretensioners that used a little Dorito to drive the mechanism, powered by the expansion of gas from the pyro reaction.
Astron aerospace has an interesting engine too. Would love to see it tied to a generator in a range extender EV like the RX vision.
https://astronaerospace.com/
Are we sure this is about the German automaker and not Mercedes going 3rd person about her various automotive projects?
Every.
Freaking.
TIME.
Seriously, this site has GOT to put in some sort of autocorrect feature so it differentiates between Mercedes the company and Mercedes the glorious writer and agent of chaos.
All the writers have to do is write Mercedes-Benz. Not a difficult fix.
In this case, me just writing “Mercedes” may or may not have been intentional because of the whole “which Mercedes are we talking about” joke going on here. 🙂
That said, I cannot speak for the others. I don’t even know if they know about the Mercedes the car vs. Mercedes the person thing.
Or maybe, hear me out because this might be a wacky idea, we the readers apply context to the article.
I’d be happy if they could remove the god damned T Mobile bullshit full page “take over” ad that has been appearing without warning constantly for what seems to be at least a month now…WTF?
And takes over the whole page…Again, WTF?
Is this a new un passive ad, or what guys?
That’s because there’s fuckery in Wankel displacement ratings. Multiply by 3. For tax purposes, NSU got the world to agree that Wankel displacement would count just one of the combustion chambers per rotor (and multiply it by 1.5, or something – more info at this Hemmings column). They’re physically small, but DISPLACEMENT is large, and they swill fuel like a big engine because they are.
Well packaged.
Displacement ≠ size.
Yep, and in some markets the displacement was not even multiplied – which is how Greece ended up with the near-mythical RX-9.
Mazda and others quoting a single chamber displacement * number of rotors is definitely misleading, but it’s more complex than that, and Mercedes (the writer) got didn’t exactly help when she said:
at the beginning of the sentence you quoted.
Three full Otto cycles are completed per rotor per rotation of the rotor, which DOES NOT equal a rotation of the eccentric shaft (crankshaft equivalent, this is where engine speed and output is measured). Each full rotation of the eccentric shaft only spins each rotor by 1/3 of a rotation, so a rotation of the eccentric shaft completes 1 otto cycle per rotor (vs 1/2 otto cycle per piston for a crankshaft).
Therefore, in terms of full cycles per rotation or air-injesting capacity, a 2-rotor, 654 cc/chamber Wankel rotary like Mazda’s 13B family will have the same displacement and firing frequency as a 4-cylinder, 654 cc/cylinder engine (so a 2.6L 4-cyl). There are still differences that affect things, such as the Wankel’s potential higher engine speed, port timings and opening/closing rates vs poppet valves, flame speed, heat losses, and combustion efficiency etc that will all affect actual air injestion and power for comparable NA engines, but to a first order a wankel rotary is equivalent to an otto piston engine of twice the quoted wankel displacement and twice the number of cylinders as pistons.
Yeah, there’s several ways to look at it – there are several ways to compare the two architectures. When you start looking at it, the Wankel inefficiencies pile up; fewer combustion events per crankshaft rotation, fixed port timing (without the benefit of the ramp profile from a camshaft/poppet valve, either), and big, inefficient combustion chamber with massive heat loss. It’s just never going to outdo a piston engine.
Even if you just double it; the 13B does worse than, say, the contemporary Mitsu Silent Shaft 2.6. And anecdotally, it was as thirsty as a GM 231/Ford Essex 3.8/Chrysler Slant Six.
Revved like the dickens, though, and the RX7 was way more fun than a Volare.
It’s all a matter of priorities. Wankels DO make a lot of power per unit of engine weight, they are VERY smooth, and as you say, they rev like hell. That makes for a perfectly lovely engine for a sports car. But the downsides of them make them rather awful for boring daily driver cars where you want efficiency, longevity, and torque above all else. And the nail in the coffin for both today is emissions.
They answer the question: how do we run a four stroke on two stroke hardware?
Very much the same as a fox is cat software on dog hardware.
LOL!
I am pretty sure that my cat is mostly running dog software. Until she isn’t and reverts to “cat mode”. Maybe she’s dual-boot?
We have one cat that’s definitely running some kind of rootkit that’s a dog emulator