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1973 Mazda RX3 - Revived Rotary

Double your power, double your fun in a ’73 Mazda RX-3

B.K. Nakadashi
Dec 6, 2013
Photographer: Matthew Jones

The world’s car companies’ great drive to Wankel-style rotary engines in the 1960s and early ‘70s was massive—and largely a dead end. NSU, the company that created the Wankel, won plaudits with its rotary-powered business-class Ro80 sedan, but fell into VW’s hands when warranty costs over failing engines drove them out of solvency. Citroen found a way to get their cars to fall apart even more quickly by installing a Wankel engine under the hood. Ford’s experiments with Curtiss-Wright rotary power went nowhere. GM spent more than a billion dollars (a lot of money today, and an awful lot more 40 years ago) developing their own rotary when emissions issues, reliability with housings and rotor tips, oil burning and excess fuel consumption killed the project outright. You’d think that the engineering world hadn’t been equipped to solve the rotary engine’s myriad problems.

Except there was Mazda. Little Mazda, who’d only been making cars since 1960, and whose tentative first steps into the States occured a decade later. Mazda, who licensed the Wankel from NSU and tasked 47 of its own engineers to tame this radical new engine. Mazda, who had to hold back the launch of the Wankel-powered Cosmo because NSU didn’t have their Wankel-powered car for sale yet. Mazda, who surely lit the hearts of American performance fans afire with tales of its on-track (and on-street) derring-do, second only to Datsun with their 510/Z one-two punch. Mazda, who managed to raise horsepower ratings during the emissions-clogged days of the mid-‘70s. Mazda, who built half a million rotary-engined cars and trucks by 1973, and a full million by the end of 1978.

1973 mazda RX 3 work equip wheels Photo 2/12   |   1973 Mazda RX3 - Revived Rotary

Yet clean RX-3s are hard to find these days: the dealer network could still be considered “fledgling” in the mid-‘70s, gas mileage—so important in small cars after that first OPEC scare—wasn’t what it could have been with other cars, and rotor-sealing issues caused some very un-Japanese-car-like issues. (Starting in 1974, some of the rotary’s sealing issues were solved with a new rotor-housing hardening process; Mazda was so confident about the fix that they offered a five-year, 75,000-mile warranty.) All of these factors impacted the number of RX-3s that came Stateside. Mix in the number that were converted to race cars, and it’s little wonder that clean, streetable examples are few and far between.

Strictly speaking, the car you see here was not clean and barely streetable when Phil Sohn of Birmingham, Alabama got his mitts on it. Buying someone else’s project is always dicey, but the Mazda bug has bitten Phil hard: over the last 15 years he’s owned eight third-gen RX-7s, an RX-8, an ’89 RX-7 convertible, and even a three-rotor, twin-turbo-powered 20B-powered ’91 Eunos Cosmo. He’s also owned a clean ’72 RX-2, and with all that in his hip pocket, it was only a matter of time before an RX-3 had come into his orbit. The RX-3 he eventually bought had some work done to it already—a lot of the hard stuff, like a coilover suspension, disc brakes on all corners, selective body reinforcements and the battery moved to the trunk and so on. This is why Phil isn’t sure of the brand names, sizes or measurements of any of the chassis components—they were all installed when he bought his rotary rocket, and work just fine as-is.)

It also came with a built carbureted 13B that Phil swears was rated at 220hp; he’s got dyno sheets from the previous owner that prove it. Honestly, that sounds a little extreme for a streetable, naturally-aspirated 13B, even for something with a ’70 Chevelle-sized Holley 750 carburetor on top and a ram-air tube where one of the headlights is supposed to be; to boot, Phil’s forte is fuel injection. Luckily, Phil knows Luis Canizales, who is well versed in carbureted engines; Luis tweaked things a little (for easier start-up, smoother running, and less hesitation when you crack the throttle) and, assuming that Luis only took the ragged edges off by fiddling with carb jetting and idle screws, it should still pump out north of 200 horses—or more than twice what an RX-3 was rated when it was new. (All the better that it’s backed by a beefier second-gen RX-7 Turbo II five-speed transmission—less chance of something going terribly awry.)

1973 mazda RX 3 custom air dam Photo 3/12   |   1973 Mazda RX3 - Revived Rotary

The body itself was previously painted silver with black rockers and a blue stripe, but had clearly seen better days: dents, chips and even rot had set in. (Alabama’s rainy season plus summertime humidity surely did the vintage, largely untreated steel few favors.) What’s more, some random bits were just missing—the vent pieces on either side of the rear window, for instance. “The body was completely restored—rusted parts were cut out and new sheetmetal was installed. I found the fender flares in Japan, and a friend of mine brought them onto the plane personally to get them back here.” The front air dam, rear wing and old-school Japanese-style fender mirrors were Phil’s additions, along with the flares. (The bumpers and side markers had been removed and smoothed by the previous owner, so at least that was done.)

Once the steel was massaged to Phil’s liking, Arthur Magarian from M7 Auto flowed the Mazda Blue Mica and Porsche Gunmetal Gray. With the extra-wide, 14-inch Work hoops poking out from under the flares, the two-tone vibe and the carbureted 13B, there is a definite ‘70s vibe going on. Your author lived through the ‘70s, a time of rainbow stripes, vans, white-letter tires and IMSA flares (sometimes all on the same vehicle); believe me when I tell you that as ‘70s/early ‘80s styles go, Phil’s RX-3 is moderate and tasteful.

It also kicks ass. Machines like Phil’s can only force us to lament for what might have been: a world where the RX-3 is less rare and more appreciated. With better distribution, with better mileage and perhaps with better initial reliability from the new-ish technology that was the Wankel engine, the Mazda RX-3 surely would have been able to grow beyond a mere cult car and into a full-blown old-school success story like so many other old-school Japanese cars have. In the meantime, its cult success remains accessible to the lucky few.

Tuning Menu
1973 Mazda RX-3

Owner Phil Sohn

Hometown Birmingham, AL

Occupation Scientific Research Lab Manager

Engine Four-port Mazda 13B; Racing Beat intake; Holley 750cfm carburetor and fuel pump; Jacobs ignition; NGK spark plugs

Drivetrain RX-7 Turbo II five-speed manual transmission with custom aftermarket flywheel

1973 mazda RX 3 four port 13B engine Photo 7/12   |   1973 Mazda RX3 - Revived Rotary

Footwork & Chassis Four-wheel coilover conversion with camber plates; aftermarket front sway bar

Brakes Custom four-wheel disc, with cross-drilled rotors

Wheels & Tires 14x9”–28 front, 14x10”–16 rear Work Equip 03 wheels; 205/55R14 front, 225/50R14 rear Toyo R888 tires

Exterior Shaved bumpers and side markers; fender flares; Mazda 808 (piston-engine RX-3) taillights; custom air dam and aluminum trunk lip spoiler; two-tone Mazda Blue Mica and Porsche Gunmetal Grey paint by Arthur Magarian from M7

Interior Sparco driver-side racing seat; 2004 Maxda RX-8 passenger-side seat; Racemark steering wheel with custom hub; custom gauges with Auto Meter fuel pressure, oil pressure and water temp gauges; Mazda RX-4 overhead console

Thanks You My wife, Marco Lau, Stephen White, Arthur Magarian from M7 Auto, Stan Chen from Toyo Tires, Luis Canizales from LCR, and Tom McGuire, the previous owner who put a lot of work into this car

Road Racing RX-3S

With the factory choosing to spend its resources on gearing up for emissions legislation, Mazda’s racing efforts in the first half of the 1970s were limited to a handful of privateer efforts. (Technical assistance would still be provided, however, and the company would keep developing their engines for competition use.) Even with special rotary mills featuring combination intake ports (a combination of peripheral and side ports), the Cosmos, R100s and RX-2s were never much of a threat to the dominant Skylines. Making matters worse, the Japanese racing sanctioning body, the Japan Automobile Federation, outlawed the peripheral-intake-port rotary design.

Once the RX-3 came in, though, it was a whole different story. A 10A-powered RX-3 took a late 1971 victory, and Mazda’s reputation was raised immeasurably with a pole position and a 1-2-3 at the Japanese Grand Prix, held in May 1972. The race engines were rated at 240hp, thanks to a 48mm twin-choke Weber carb and a set of side-intake auxiliary bridge ports, which extended into the trochoid housing. These caused much interest at the post-race tech-in, and the JAF soon modified its earlier ruling, decreeing that at least 50 engines so equipped would need to be offered over-the-counter. Quickly, it became a rival for the previously untouchable Nissan Skyline GT-R.

1973 mazda RX 3 mazda 808 rear taillights Photo 11/12   |   1973 Mazda RX3 - Revived Rotary

From there, the floodgates opened. Mazda RX-3s won the Fuji Grand Champion-series Super Touring Car championship in 1973, ’75, ’76 and ’78. By the middle of the 1976 season, the RX-3 had won its record 100th race. Suspension tweaks led teams to develop a Watt linkage ahead of the rear axle, a setup that was later used in the first RX-7s. And that says nothing of the healthy SCCA and IMSA stock-bodied race series victories and championships that the RX-3 won throughout the ‘70s, and even into the ‘80s.

The RX-3’s official factory competition life ended with a whimper: a pair of Gatorade-sponsored racers were dispatched to the ’78 24 Hours of Daytona, in preparation for Mazda’s grand return to the track with the upcoming RX-7. Alas, the fine Florida sand got past the air filter and made a mess of the 12A’s tender rotor sealing, while a sudden rain shower changed the track and operating temperature so rapidly that it literally split the exhaust system open—a sad end for a great racer, but one that ultimately paved the way for the RX-7s.

1973 mazda RX 3 mazda shifter Photo 12/12   |   1973 Mazda RX3 - Revived Rotary
By B.K. Nakadashi
31 Articles

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