Conventional gas and diesel engines do a commendable job serving car and truck owners’ needs, but futurists insist that electric motors will eventually supplant them as the power source of choice. Some 50 years ago, a similar situation cropped up: Mazda’s ultrasmooth rotary engine had bright hopes of sending pistons the way of the buggy whip. With Mazda celebrating its 100th birthday this year, what better time to toast the brand’s most ambitious technical stride?
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In the early days of IMSA, a team that shall remain unnamed tasked us to improve the sealing of the rotary engine in their racecar. We devised a ceramic Apex seal backed by a high-temp Belleville spring that worked great... on the dyno. Real world testing in the racecar showed a distinct dropoff in power after about two hours of run time. A teardown revealed that while the ceramic seals were intact, they had decided to become very effective lathe tools and had enlarged the housings dimensions to the point where it wasn't as designed. We tried an experimental compressed carbon (very early version of carbon/carbon like current brake rotors) design, but it flaked badly in short order. We had a well-known piston ring manufacturer ready to produce a moly-filled seal, but the team pulled the plug on the program. We kind of pursued it in-house for a bit by designing a ceramic housing liner, but that octopus kept growing more arms and we shelved the whole deal.
Interesting article. I did my Master's Thesis on the exhaust emissions characteristics of the Mazda rotary engine. It was an early (1970) R100. Interesting comparison with the Chevy V-8. Actually without its accessories the R100 Engine itself weighed about 125 pounds and put out an honest 100 BHP as measured on our dyno. We originally were going to do a comparison test with the "State of the Art" for the day Vega engine but the Vega engine vibrated so badly that it would not hold a setting on our dyno. The Wankel is a remarkable engine in many ways - would hate to see it disappear completely...
Thanks Don for such a comprehensive enlightening article. I do recall that Rolls-Royce had a diesel version to install in a military tank and on the other end of the spectrum there is rotary engine for model airplanes
I had a RX3 wagon, 1973 IIRC, due to publics concern about longevity of the rotary, Mazda gave a 50,000 mile warranty on these engines. My apex seals failed at a little over 50,000 miles (less than 51,000). Mazda would not help me at all, no good will discount, no nothing. I had the engine rebuilt, drove it for a while longer, and traded it in on my 2nd BMW.
Later there was a class action suit which Mazda lost and I recouped $600 or $700 or so.
An RX-2 race car "idled" past me in the pits at Laguna Seca, many years ago. Even at idle the hideous splattering sound of a thousand chainsaws ripped the otherwise, modest sounds around the pits. I could not even imagine how loud that car would be under full power on the track...luckily for me and others, the car's track time came the next day, after I was in the comfort of my own home.
I remember the 787B at Le Mans and it was a truly awe inspiring beast. The noise as it passed by was wonderful as a spectator but I dread to think what is was like for the poor souls in the cockpit. I would imagine winning at the Sarthe was some degree of consolation though.
Others tried various "alternative rotary" engines over the years, the most interesting one was the Isuzu rotary introduced around 1964, never built. It was sort of an inside-out Wankel with the figure 8 as the rotor and 3-sided chamber, with seals in 3 places inside the chamber rather than on the rotor! When asked at the Tokyo auto show in period, the engineers could not describe how it worked!
If any one commenting wants to see where the rotary is strong then look no further than drag racing in Puerto Rico, Australia and New Zealand. !3B motors running 6.5 seconds in the quarter being fed a large amount of methanol with the help of massive 90+mm turbochargers. The rotary engine lives on strong and it has revered status for some. I own two and if I had the room for more cars, I would definitely own an Rx2 and a 3rd gen Rx7 with a 3 rotor swap for fun street use.
My first personal experience with the rotary engine was in the 1971 Arctic Cat 303 Panther snowmobile, as mentioned, with engine made by Sachs, under license from Curtis Wright, I believe. Of course, these used 40 to 1 fuel/oil mix, and was only 20 h.p. rated, but the machine ran flawlessly for many winter seasons, albeit with about a gallon per hour fuel consumption, as I recall. Years later, my significant other bought a new 1986 Mazda RX7 with 5 speed manual, which I immediately drove to Key West from NY, and back, and she kept for a few years with no problems, as well.
I own an early 79' model RX-7, and enjoy driving it on weekends. The carburetor is more of a concern to me than the 12A engine at this point in time. You just don't see any of these on road anymore.
I'd love to see an RX-9, but without a hybrid system or cheaper alternative fuels, it doesn't seem very likely. However, if Mazda is looking to prove me wrong, I am ready with a deposit. Until then I will keep enjoying my 1991 RX-7 Turbo.
I had a 1989 RX-7 GTU, wasn't the fastest thing going, but was a blast to drive, the 50/50 weight distro so throwing it into corners was pure joy! And of course everyone always freaked out when I told them it had a whooping 1.3 liters and was a rotary...was a conversation piece among gear heads for sure!
I sold the car a few years ago when it was just becoming too difficult to service the engine and (at least in my area) mechanics don't want to touch a rotary because they are just not familiar with them.
Sadly, I think the time for rotary's have come and gone and that is a disappointment...I do miss my RX-7!
I love getting my monthly hagerty magazine for all its great articles. My secret though...I'm always looking for a mention of what seems to be -the most unmentionable car in all automotive circles. Its like once you mention these cars...you've mentioned everything, and it's time to change the subject. That car, dare I say is the, nearly extinct, GM Hspecial clones..The Monza, Sunbird, Starfire and Skyhawk.
In this article, I knew I had a gleaming hope. Just a few pages earlier.. In the same issue, in the Mustang article on Pg.76, the lowly Mustang II was receiving some quite controversial, yet much overdue praise and ranking.
So I turn the pages and heres a deep and detailed story about the Mazda rotory engine. Surely they must be mentioning the period around 1973/74 where it was going to be GM"s new big deal for a new futuristic small car!
A few pages in and it looked like perhaps that had been deliberately glossed over...strange, but like I mentioned I'm no stranger to my favorite "likeable lookalike" to be completely overlooked.
But then....There it was... I see 'GM' in the paragraph and I think I've struck literary gold.. Then .... fools gold! They mention the car GM was going to put it in as the Vega and also mentioned the amc Pacer, for some hoopla, and to get gracefully passed having to mention the MONZA! MONZA MONZA! C'mon... Isn't it a great name when it's a race track in the hills of Italy, or a Corvair model? Maybe not so much for a swoopy new disco era subcompact. That almost had a different name (see below) Wierd coincidence that it sounds close to Mazda. (anoyingly so to the uninitiated observer who says Chevy Mazda? when I have to explain what my little Spyder decaled car is).
Now... Technically, the article IS correct, in saying it was for the vega... The Vega -Chassis-. GM's Irving Rhybicki & Bill Mitchell, had super slick new body style penned up. Bearing styling cues, fully ripped straight off of a Ferrari 365 gtc+4. Rumour has it that a Vega chassis, and the drawings ( and perhaps the swoopy new clay models) were shipped over to Pinninfarina, to see if it would be possible to manufacture that new shape onto the vega chassis, at the assembly line speed of the Vega. They sent back a working prototype..(pictures are on the web including shots of the prototype engine installed, and a few years back a rare rotory front emblem for the car went up for sale on ebay). And the rest is history. Well almost.. As the article stated, GM canceled out of the wankel, with the factory tooled up and ready to produce the 'MONZA'...(To a bummed Jim Hall, who almost got a dollar per car with what it might have been called the 'Chapperal'). The only thing left to do was offer the Vega 4cyl...and Lucky for enthusiasts, and probably because of the success of the Mustang II... a Small Block V8! There is a remaining vestigal of this rotary endeavor GM bailed on, to be seen on any of the near extinct examples, if you can find one still sporting the stock hood. A 'Power bulge' as Dodge coined the term to a similar shape years later appears in the center of the hood of the Monza. It was supposed to have a low porsche-like center section, afforded by the low keg like shape of the rotory..but now has an unusual center bulge to clear the forward pully of the tall Vega OHC 4 cyl. In pure Italian esq flair, it's not unlike a 'camel toe' worn loud and proud on a hood with enough shape to harken to Ferarri's produced decades later. Quite a bold bulge for a somewhat modest and conservative stable of Chevrolet's at that time, maybe a bit embarassing enough for people to just want to overlook that uber sexy..'sex sell's design from the outlandish era of the disco themed mid to late 70's. Or maybe just customized shaggin' wagon Van's were all the rage. Finally, like most GM design's the final product would likely have also been a bit heavy for the Rotory, likely stalling any performance that could match its good looks. So Lucky for hot rodders like me, the Small block Chevy found it's way into lightest chassis ever. (shoehorned in, but there nonethelss) First a tinier than the original 265 v8 at 4.3 liters and 262.5ci and later a mightier 305, for the later years. California models even got a detuned 350 for the first 2 years).. And still Great for the Camaro to! (See article on Pg. 80) ...Having had that unique torque arm solution to all that torque in such a light duty unibody structure, surely helped pave the way for the future of a modern Camaro from 1982 and beyond, which utilized a nearly identical design right up through the 1990's. But Camaro guy's will never admit their root's are in a Vega based Monza, instead of a 69. Cheer's..
One of the things that plagued poor Rudolf Diesel was that the difference between his patent and the Otto engine was more complicated than compression ignition... some early Otto variants had compression ignition
Anyhow, one of my biggest complaints with the modern automobile is that emissions, safety standards, and picky customers have so overly optimized the car that there is not much interesting going on under the hood. it will be sad to se one of the last unusual engines go.
My father was an engineer at Hydra-Matic Div of G.M. where the rotary engine was totally tooled up from manufacturing, to assembly, to test. I also worked there at that time in industrial engineering. My fathers responsibility was the machining of the rotary housing. As the article says the problem that Nissan had was the life of the seals caused by the irregular machining of the housing. My father Raymond Happy patented a machining process along with GM that solved the wear problem. (Look it up on Google Scholars under Raymond Happy). Unfortunately like the article says the first oil embsrgo hit and the rotary engine was a very thirsty engine and GM pulled the plug. What a shame all set and ready to go but shut down. Ray Happy
The Amateur airplane builders raved about the power to weight ratio of the Mazda Wankels and there are several builders who stayed the course. The Mazda, with its faults, is still lightyears better then the 1930's tech Lycomings and Continentals still being built....but, it has to be said, the Lycomings are still more reliable.
I had a 1974 RX-3 and it was a great experience. I put over 100K miles on the car before I sold it. It was still running strong but oil consumption has increased to about 450 miles per quart. Fuel economy was disappointing. 18mpg was about the tops. It was the smoothest running car I've ever owned. At 30-35 mph you couldn't hear any engine noise what-so-ever. Got rubber in second gear with ease and even chirped the tires into third gear a few times. No engine work required. The car was hard on exhaust systems and I had to replace the electric fuel pump two times.
It's future? Museums. It's biggest feature was hype. In an industry that lives and dies on CAFE numbers and a shift away from gasoline power, it doesn't have a chance and really never did. To generalize, 100 HP from the weight of a 70 HP with the fuel consumption of a 130 HP engine?