Rotaries that defined Mazda’s first U.S. decade ...

Historical past of the Rotary

Within the mid-Fifties, famous German inventor and engineer Felix Wankel (pronounced Vahnkle) patented the primary new inside combustion engine of the twentieth century. Wankel’s invention, which grew to become often known as the rotary engine, first sputtered to life in 1957. 4 years later, an engine designer from the Japanese agency Toyo Kogyo (now kown as Mazda) noticed the present operating mannequin, which was produced on the time by Germany’s NSU.

“I felt a real shock after I first noticed a operating prototype of the rotary engine in 1961,” mentioned that engineer, Kenichi Yamamoto. “It was so compact and turned so easily. Like several engineer, | was impressed by the novelty, as a result of there was so little variation in inside combustion engines on the time. I felt a passionate want to problem and excellent the rotary engine.”

Yamamoto was put accountable for rotary engine improvement and superior quickly by means of the corporate. He finally grew to become chairman and CEO of Mazda.

After 5 years of strenuous improvement to organize the rotary for manufacturing, Mazda launched the 110S, also referred to as the Cosmo Sports activities, for the 1967 mannequin yr. This sports activities mannequin, outfitted with a 110-horsepower, two-rotor engine, drew raves from the house market critics. Nevertheless, it was by no means imported to the U.S.
 

The Wankel Engine

The rotary engine operates similarly to a two-cycle piston engine in that the combustion goes on repeatedly. As well as, all three sides of the triangular rotor keep it up the cycle concurrently. These elements are what give the rotary engine its glorious power-to-weight ratio. Different benefits are a whole lack of any valve gear and a small reciprocating movement of the rotor, which provides it inherent smoothness and high-rpm functionality.

Nevertheless, the rotary engine’s gas effectivity is poor because of the excessive surface-area-to-volume ratio of the combustion chamber in the meanwhile of ignition, which causes quenching of the flame entrance and incomplete ignition. This urge for food for gas could be the engine’s crux.

We are able to use our illustration on web page 77 to comply with the combustion cycle of 1 facet of the triangular rotor. In determine 1a, the rotor apex seal has swept previous the consumption port and has begun to attract within the air-fuel combination from the consumption manifold. In determine 2a, the second apex seal has handed the consumption port and compression has begun. Determine 2b reveals the purpose of most compression, which is designated at TDC (high lifeless middle); the spark plugs fireplace at or close to this level. Two spark plugs are required for every rotor due to the lengthy, skinny form of the combustion chamber.

In determine 3b, the fired cost expands (that is the facility stroke), whereas determine 4a reveals the uncovering of the exhaust port and subsequent launch of spent gases.

Lastly, determine 4b reveals the top of the exhaust section and the simultaneous starting of the subsequent consumption section. Inevitably, there may be some mixing of the exhaust gases at this level, however this solely serves as a pure type of exhaust fuel recirculation. This additionally reduces the extent of hydrocarbons and nitrous oxide emissions.

R100, 1970-72

The primary Mazda to be exported to America was the R100. Launched on the West Coast in 1970, this was a really ordinary-looking small Japanese sedan outfitted with a 60-cubic-inch (982cc) two-rotor engine designated the 10A. In making the R100, Mazda merely took a piston-powered automotive already in its steady—the Familia coupe—and put a rotary engine beneath its hood.

The R100 offered in very small numbers, primarily within the western a part of the U.S., resulting from an absence of nationwide promoting and gross sales shops. It was nonetheless a really spunky automotive—100 horsepower at 7000 rpm—with exceptional smoothness and calmness. The R100 was by no means offered in nice sufficient numbers to be homologated for street racing; consequently, this automotive isn’t authorized for SCCA Improved Touring or GT class competitors. Once in a while an R100 will pop up in public, however for essentially the most half these automobiles are extraordinarily uncommon.

RX-2, 1971-74

In 1971, Mazda started to assemble a nationwide supplier community within the U.S., ranging from the West Coast and transferring eastward. The sedan chosen to characterize the marque in American was the RX-2. This automotive sported a rotary engine (12A designation) that had been enlarged to 70 cubic inches by widening the rotors of the 10A to 70mm. This created solely a small improve in size, however raised the facility output to 120 horsepower with full U.S.-spec emissions controls.

The consequence was a small, unassuming-looking sedan that was able to 10-second 0-60 occasions. This made the RX-2 a lot sooner than some other small automotive of the day; it was even in a position to outrun many 350- cubic-inch V8-powered automobiles. Sadly, the Wankel’s urge for food for gas was commensurate with its energy, so when the gas disaster of 1974 hit, gross sales figured dropped by means of the basement.

Mazda tried to work with the occasions, detuning the 12A to ship 102 horsepower in 1972 and solely 97 horsepower in 1973. Together with the drop in energy got here large chrome bumpers added to fulfill federal necessities for crash safety.

One of many first rotary race automobiles was the RX-2 sedan constructed by Jim Mederer and Ryusuke Oku of Racing Beat and raced within the 1973 IMSA RS sequence by Patrick Bedard of Automotive and Driver journal. This automotive, which sported a 218-horsepower, bridgeported engine, took two wins and one second-place end in 5 races.

The RX-2 had a lot extra high finish pace than the opposite automobiles within the class (principally Gremlins and BMWs) that Bedard practically lapped the sphere at Charlotte Motor Speedway. IMSA promptly modified the foundations for the 1974 season to disallow porting fully.

The automotive did take pleasure in an extended racing profession, regardless of the IMSA ruling. These days the 1972 RX-2, with its svelte chrome bumpers and better engine output, has gained considerably of a cult following within the U.S. Mazda RX-2s are nonetheless seen in SCCA’s Improved Touring and GT ranks, regardless of the presence of newer and extra fashionable automobiles which have displaced the RX-2. Due to a light-weight curb weight, the RX-2 can even been seen at import drag races.

RX-3, 1972-78

The RX-3, which was imported starting with the 1972 mannequin yr, was smaller and lighter than the RX-2, with a 91-inch wheelbase that was six inches shorter than its predecessor’s. The RX-3 shared the identical rotary engine, so it had the smoothness and energy that made these engines well-known. 

The RX-3 was Mazda’s greatest vendor by means of the ’70s, promoting about 20,000 models in its greatest yr (1973). It was additionally avail­ready in a station wagon model, which professional­vided an attention-grabbing mixture of efficiency and practicality.

The RX-3’s engine, although identi­cal internally to the RX-2’s, was rated at simply 90 horsepower within the 1973 mannequin yr resulting from a extra restrictive exhaust system. For the 1974 season, nonetheless, the l 2A’s Hitachi-Stromberg carburetor was changed with a Nikki four-barrel, yielding elevated efficiency. Bigger consumption and exhaust ports within the rotor hous­ing additionally helped efficiency, and the apex seal materials was modified from carbon-im­pregnated aluminum to metal, thereby enhancing sealing and reliability. 

Additionally, the massive O-rings that separated the water passages from the combustion cham­bers between the housing got a Teflon coating, which eradicated a frequent reason for engine failures within the earlier engines. 

From 1976 by means of 1978, Mazda professional­duced the RX-3SP, which had a boastful tape stripe and spoiler package deal that will put a up to date Trans-Am or Camaro Z28 to disgrace. For early rotary followers, the RX-3SP represents the Holy Grail of the mannequin run.

The RX-3SP’s in depth record of beauty en­hancements included blacked-out trim, facet window louvers, an aggressive stripe package deal, a rear lip spoiler and one of many largest cow catchers ever fitted to a manufacturing automotive. Mazda additionally outfitted the mannequin with a unique cen­ter console, tail lights, entrance seats and sprint. These choices teamed as much as make a wild-look­ing manufacturing automotive, though technically the stripes and spoilers had been choices put in on the automotive’s port of entry.

The RX-3SP additionally obtained some delicate efficiency upgrades, like a bigger radia­tor and outsized oil cooler. A few of the automobiles additionally got here with bigger rear brakes, and each RX-3SP produced got here with a 5­pace transmission. 

The automotive additionally got here with a short-nose differ­ential just like the one fitted to the early RX-7. This differential accepts a greater variety of rear finish gears than the one fitted to stan­dard RX-3 automobiles, however required Mazda to make use of an extended driveshaft.

The RX-3SP’s engine differs from the remainder of the RX-3 manufacturing in just one manner, as a novel dual-runner consumption manifold with longer primaries and shorter secondaries automotive­ried the inventory four-barrel carburetor in 1976. “Sounds prefer it ought to make 15 further horse­energy,” says Floor Management’s Jay Morris, a long-time rotary racer, “however it does not appear to be.” Testing between the RX-3SP consumption manifold and the inventory one does not appear to make any distinction in energy or driving manners, Jay stories. 

For those who’re available in the market for an RX-3SP, there may be a straightforward solution to inform an actual one from a faux: the real article will function a small dent on the within of the hood so the over­sized radiator suits. The RX-3SP additionally got here with an emblem on solely the correct facet of the automotive, so do not be postpone if the automotive seems to be prefer it’s lacking one. 

Just like the RX-2, the RX-3 was a hit within the racing world, with wins in IMSA, SCCA and even drag racing. In 1974, Racing Beat ready a 13B engine to 280 horsepower, put in it in an RX-3, and turned it over to Don Sherman for an assault on the Bonneville Salt Flats. Sherman, who was additionally an editor at Automotive and Driver, set a brand new G Manufacturing class file at 160 mph. 

RX-4, 1974-’78

The RX-4 was the most important and just about the final of the rotary sedans. Intro­duced in 1974, it sported a 99-inch wheel­base and weighed greater than 2700 kilos, making it about 400 kilos heavier than the RX-2. Offsetting this weight, nonetheless, was the brand new 13B engine, which displaced 80 cubic inches (1308cc) and produced 110 horsepower in inventory type. This was sufficient to propel the RX-4 to low-nine-second 0-60 occasions, making it the quickest Mazda to this point.

Sadly, the enhancements to the RX-4’s engine compartment didn’t carry over to its suspension, which was sufficient at greatest. The automotive had McPherson struts up entrance and leaf springs within the again, an association much like that of the RX-3; this de­signal tended in direction of heavy understeer in inventory type.

Busy inside and exterior styling, poor drivability due to primitive emissions tools and dismal gas economic system (bear in mind, the fuel crunch was in full swing) did noth­ing to assist RX-4 gross sales within the U.S. 

Cosmo (RX-5), 1976-’78

You may’t inform the story of the early Mazda rotary automobiles with out at the very least mentioning the Cosmo. Mainly, Mazda constructed a luxurious cruiser out of the RX-4. Though it shared many specs with the RX-4 (wheelbase monitor, engine), the Cosmo seemed decrease. wider, and simply larger.

The additional measurement did not precisely assist efficiency or gas economic system, and the Cosmo offered in very small numbers. The automotive’s excessive level most likely got here in 1976, when Ray Walle, proprietor of the Z&W Mazda dealership, drove a Cosmo to an 18th-place end on the 24 hours of Daytona.

We also needs to point out, in the identical breath because the ill-fated Cosmo, that Mazda constructed a ro­tary-powered pickup. Offered within the U.S. from 1974 by means of 1976, the appropriately-named Rotary Pickup featured the identical 110-horsepower 13B discovered within the RX-4.

Modifications Galore

Mazda sedans have turn into extraordinarily uncommon on the streets, however nonetheless populate the race tracks of the U.S. They’re significantly fashionable on the SCCA Improved Touring circuit, the place they run in ITA. In SCCA Solo II autocross competitors, the RX-2 and RX-3 fashions are categorized in C Avenue Ready, whereas the heavier RX-4 and Cosmos are put in D Avenue Ready. 

If a rust-free physique may be discovered, virtually every thing else on the automotive is buf!et­proof, which makes for a really pleasing race weekend. When wanting over a professional­spective Mazda se­dan buy, verify for rust on the body rail beneath the battery field on the proper entrance nook. Restore of this space may be very tough.

The most well-liked engine in use is the 1974 12A rotary, resulting from its bigger port measurement. Correctly ready, this engine is able to about 150 horse­energy. Additionally fashionable are 1974 13B engines–that are used within the RX-4–and the RX-3SP 12A engines with their distinctive, crossed consumption manifold.

The key to ex­tracting horsepower from a rotary is to assist it breathe higher. Though SCCA requires inventory carburetors in IT, the unique Nikki four-barrel works fairly effectively as much as 170 horsepower with the right jetting. IT guidelines do enable the entire elimination of all emissions management parapherna­lia, which is extremely beneficial to wash up the consumption manifold stream.

The true secret is the exhaust system. Many of the high groups run what is called an extended­major system, which implies that the tubes from the 2 rotors usually are not collected till simply earlier than the rear axle. Two-inch-diameter tube headers ought to be used with the identical measurement pipes hooked to a three-inch SuperTrapp muf­fler with no baffles. The concept is to have as little restriction as attainable within the exhaust. This sys­tem may be very noisy, however meets the same old 105 db restrict with a number of decibels to spare. Nevertheless, ear plugs are beneficial.

Whereas many of the lifeless automobiles have already been despatched to the crusher, a couple of boneyard tips do exist. “No less than round right here, you will not discover outdated RXs within the yards anymore,” explains Sh­annon McMasters, proprietor of Dallas’ Import Motorsports, a Mazda tuning and restore store.

“The one junkyard stuff that may work now is early RX-7 components. 1979-’80 RX-7 five-speeds match within the 2s and 3s, however you’ll have to shorten the driveshaft. 1979-’82 Posi models match the 2s, however not the entire 3s (solely SPs). The second-gen motor suits if you could find a carb setup for it. The most affordable setup is a ’79-’85 12A carb motor swap-gets you the motor and carb multi function and nonetheless plenty of components round.

“There are nonetheless components round–inventory and race–from Mazda Comp and small retailers like mine which have been engaged on RXs for a very long time and nonetheless have new and used stuff round.” 

Shopping for a Automotive

For lots of enthu­siasts, the early Mazda RX automobiles rep­resent the cool facet of the ’70s-like having a ’78 Bandit Version Trans-Am or Donohue AMX Jav­elin on a smaller scale. Whereas the RX automobiles weren’t tremendous quick in inventory trim, take coronary heart that basically nothing else of the time was. Fortu­nately, a complete sub­tradition of tuners are ready to assist flip that once-dodgy RX-4 right into a fire-breathing beast.

“As for greatest early automotive, it must be the ’71 RX-2,” ex­plains Shannon. “It was the lightest of the automobiles, had a real vented hood, coil­over rear suspension, and the RX-2 had the motor mounted far­ther again within the chas­sis. The RX-3 had a shorter wheel base and a leaf-spring rear suspension, however a smaller frontal space. The ’76-’78 RX-3SP is a uncommon and neat automotive additionally. That they had a bitchin’ physique equipment for his or her day.” 

On the opposite facet of the coin, due to the heavy, federally­mandated bumpers, the 1974 RX-2 and 1974 RX-3 are the heaviest of the sequence, so you might wish to keep away from them. Nonetheless, over the past 25 or so years, plenty of these automobiles have had their bugs re­moved.

“Most of those automobiles by now are removed from inventory,” Shannon ex­plains. “Inventory was not excellent anyway. Most already have newer motors and up to date sus­pension methods in them. Mine, for instance, has a six-port 13B with Dellorto carbs, MSD, light-weight flywheel, five-speed transmission, Posi, 4.11 rear finish, and some suspension mods. However but it seems to be like a inventory ’71 RX-2, which actually surprises the Mustangs and newer RX-7s when it spanks them.”

Like a variety of automobiles from the ’70s, these early Mazda sedans are recognized to rust–particularly in areas the place the roads are salted within the win­ter. “When older automobiles to purchase, the RX-2s had been recognized for the trunk areas ru t­ing out,” Shannon notes. “The RX-3s had an issue with the physique splitting across the backside of the door frames.”

The Rise and Fall of the Rotary

These early rotary-powered Mazdas had been solely a glimpse of what was to come back. In 1979, the yr after the RX-3, RX-4 and Cosmo left U.S. shores, Mazda unleashed the rotary-pow­ered RX-7 upon U.S. customers and eventually struck pay dust.

However as most fans know, even the RX-7 had a rocky experience. Issues began off with a bang in 1979, as sellers had been com­pletely unable to maintain up with demand. The RX-7 frenzy slowed with the 1986 launch of the second-generation RX-7, which was extra of a boulevard cruiser than an outright sports activities automotive, however picked up once more with the su­per-fast, turbocharged third-gen RX-7 in 1993. Nevertheless, reliability issues with these remaining automobiles left many followers with a bitter style of their mouths, and the final rotary­powered Mazda was offered within the U.S. only some years later.

Or was it? Phrase on the road is that Mazda has extra rotary-powered automobiles certain for U.S. shores. There’s speak of a few pos ible Wankel offspring showing within the close to future, together with an RX-7 substitute and/or a sedan. There is no official phrase from Mazda on this level, so we are able to solely watch, wait–and hope.