For the new rotary runner, more refinement and better behavior
Mazda RX-7 GXL by Larry Griffin -- Car and Driver -- November 1985
Mazda had a winner in the RX-7 from day one. Introduced in 1978, its Wankel engine provided a hearty sportiness that wooed sales from increasingly glitzy and hefty competitors. The original RX-7 lasted a phenomenal seven and a half years.
The new RX-7, except for its nameplate, general layout, and basic engine design, is all new. Mazda offered us two chances to drive pilot-production versions of its rotary toy, and we zipped all over Southern California and Washington state.
Yes, you've seen this car before. The new nose looks quite Porsche-like. The sides are straight off a Daytona Turbo Z. The rear has been rounded up from a Camaro Z28. The wheels look as if they were nidnight-auto-supplied from an Opel Senator. Fortunately, the collage is attractive. All the badges were camouflaged on the car we drove in California, and passers-by always blurted the same question: What is it? The nose and the tail wear plastic bumper beams and fiberglass-reinforced urethane bumper covers colored to match the body. "Flash to pass" light ports snuggle in the front bumper just below the retractable halogen headlights; articulated linkages allow the headlights to sit upright when retracted, so the same lever that switches between low and high beam at night will also flash passing warnings through the ports when the lights are down for aero efficiency during the day. In this retracted state, the new RX-7's basic drag coefficient is 0.31, and it drops to 0.29 with an optional aero package.
Mazda intended to build a much more solid unit body for the new car, and the old RX-7's tinny feel of panels and pieces rustling together is indeed gone. Shored up by massive window frames, the doors clump tightly shut. The structure feels rigid—no hinges, no twinges. And,, although the overall length has shrunk 1.2 inches, to 168.9, the wheelbase has been lengthened 0.4 inch, to 95.7 inches. The track and the overall width are each increased roughly an inch, and the curb weight is up to 2700 pounds, roughly 100 pounds more than the old model. At the anguished request of dealers and rug rats, Mazda is finally offering a two-plus-two option in the States. The new RX-7's folding back seat is about the size of the one in the 944: minuscule. Unlike the famous stretched Nissan Z two-plus-twos, the four-seat RX-7 shares the same basic body shell with the two-seater.
In offering additional seating positions and more contemporary styling. Mazda is obviously responding to the wants and needs of the market as it did so brilliantly in 1978, when the original RX-7 was introduced. However, this time around, value is not the single-minded priority it used to be. The early word is that base prices will start at around $12,000 for the two-seater and step rapidly upward, peaking out at about $18,000 for the leather-lined and compact-disc-player-equipped GXL.
In tooling up for a new car, Mazda considered three basic alternatives. The first was to face-lift the RX-7 without major chassis changes. The second and wildest option was to redo the whole car and go for broke with an electronic-display instrument panel, a rear-mounted transaxle, electronically controlled power steering, and a fully independent and self-adjusting suspension. The third alternative (and the one picked) was a slightly more conservative approach: no video-arcade instrumentation and no transaxle, but bring on the best suspension, brake, steering, and wheel-and-tire hardware available to make the RX-7 competitive in performance with whatever the world has to offer for less than $20,000.
Like every car maker these days, Mazda was after better handling. The idea was to induce the RX-7 to track as if by second nature, and to turn into corners crisply, but to avoid the old rear-axle side step at the limit. Both the standard model and the GXL share a new rack-and-pinion steering gear designed with high rigidity in mind. To enhance straight-ahead feel, the rack itself has been machined with a 0.5mm bulge at its center to tighten rack-to-pinion contact at this critical point. To upgrade GXL models, Mazda gives them a special electronically controlled power-steering system. Sensors monitor road speed and steering angle every 0.3 second and feed this information to a computer that varies the power-steering assist supplied by two tandem hydraulic pumps. The harder you drive, the less the assist. The results are very light, enjoyable steering at low speeds, and firm, stable tracking at high speeds.
Mazda's anti-oversteer solution, called Dynamic Tracking Suspension System, involves a semi-trailing-arm rear suspension, a design normally known for inducing tail-happiness. In this case, however, bad habits are held in check by an amazing array of mechanical Band-Aids. Complex linkages and bushings react to fore-and-aft and lateral load and in doing so coerce the rear geometry into steering for better instead of for worse (see Technical Highlights). As unlikely as this sounds, you can indeed feel it working. At the first sign of your steering input for a hard corner, the car dives for the apex and the rear tires get to work pronto. You think maybe you've overdone it as you feel the tail get up to step out, but then the set of the chassis retreats through neutrality and cossets you back into understeer.
The RX-7's quick steering response owes much to the front suspension's modified MacPherson-strut layout. Forged-aluminum control arms and wheel hubs were chosen to provide the necessary stiffness with the least unsprung weight, and the suspension's mounting system is specially designed to resist lateral and twisting forces while discouraging dive during braking. Longitudinal stiffness through the rubber mounting bushes is low to minimize impact harshness over bumps.
The RX-7's ride qualities can be adjusted by switching the console button for the Auto Adjusting Suspension from the normal to the sport setting. Sensors monitor car speed, lateral acceleration, longitudinal acceleration and braking, and steering-wheel angle. A microprocessor analyzes the information, then picks the desired damping from three possible settings: normal, firm, and very firm. When the driver chooses normal, he gets the normal setting both front and rear up to 50 mph, then a firm setting in the front beyond that speed. IN the sport setting all the shock absorbers operate in the firm position until the microprocessor detects notable destabilizing forces, at which time the valving is switching to very firm at all four corners.
The rolling stock is low in profile to benefit from the latest tire technology on the market. Base cars were 185/70HR-14 tires on 5.5-inch steel or aluminum wheels, and the GXL gets 205/60VR-15 tires on 6.0-inch-wide alloys. The RX-7 Turbo, when it arrives in a few months with another 40 or so horsepower, will war V-rated 205/55s on 7.0-by-16 alloys.
The heavily finned, forged-aluminum, four-piston front brakes and the single-piston rears squeeze ventilated rotors, and they feel good through the pedal, production few doubts either in scorching mountain runs or on the test track, in 186-foot stops from 70 mph. Few cars tell you so clearly that worthy mechanical bits are working in your favor.
Under the hood, a long list of rotary-engine improvements keeps the RX-7 humming along nicely in its new, more upmarket role. Last year, two displacements were offered, but only the larger 13B engine is back for 1986 duty. It displaces 1308cc (compared with the original RX=7's 1150cc) and breathes through a sophisticated six-port, tuned-length induction system. Fuel delivery is through four injectors managed by a digital electronic engine-control computer. Thanks to Mazda's persistent development of the rotary, the RX-7's power, torque, and fuel economy are all improved: compared with last year's 13B, there are ten more horsepower, five more pounds-feet, and about one more mil per gallon (both city and highway) to play with. If this isn't enough to tickle your interest, Mazda has the turbocharged 13B on the way, as well as intentions of unveiling a pure-racing three-rotor engine sometime during 1986. Yes, sports fans, the new car's engine bay is roomy enough to swallow this triple-scoop rotary if it becomes practical for production.
On the road, today's two-rotor, normally aspirated rotary feels quite lively, quicker to respond than its predecessor, perhaps because the former howling exhaust hum has been muted. The fifth wheel freezes the swift-moving RX-7 at 7.7 seconds from 0 to 60 mph and 16.0 seconds at 86 mph for the quarter-mile. Mazda claims a top speed of 128 mph. All in all, the new and heavier is about as quick as a 1985 GSL-SE, so it's clear that the more potent engine and the cleaner aerodynamics are working in your favor.
In the cockpit, the shifter and the pedals are sturdier, and they're placed better than ever. The seats are genuine wraparound performance items, multi-adjustable for proper support and reach to the tilt-adjustable wheel. Unfortunately, the extra-cost leather upholstery may drain performance out of a hot driver in warm weather, even when the otherwise adequate air conditioning is pumping at its upper limit. The instrument layout is first-cabin, but the red-orange markings can be less effective than pure white-on-black markings, especially on a sunny day when sunglasses mask detail in the depths of the instrument pod. The rest of the RX-7 ergonomics are fine. Love those wacky pinball-flipper controls on the dash pod that keep the wipers and the smooth cruise control in play.
There are two things we'd get rid of for sure: the two-spoked steering wheel, for a proper three- or four-spoked sport wheel; and our old RX-7, if we had one, for a new RX-7. Then we could go out and give fits to folks in old RX-7s. But then, human nature being what it is, those folks will just slip into the RX-7 Turbo the moment it rushes ashore, and the escalation will start all over again. The RX-7 does nicely in this escalation business: a winner from day one, still a winner.
- Rotary Refinements
Improvements to Mazda's 13B two-rotor Wankel for 1986 include: a new microprocessor-based engine-management system to control fuel delivery, ignition, and emission controls; relocated spark plugs (leading and trailing igniters are now 5mm closer together); a new multi-chambered exhaust-port inset to soften the exhaust note; a dual-muffler exhaust system; reduced cooling-jacket capacity (to speed warmup); rotors that are lighter by fourteen percent; a thick steel liner for the rotor housing; a new Teflon coating for internal wear surfaces; and twelve instead of nine eccentric-gear mounting pins for increased strength. Horsepower and torque are up by seven and four percent, respectively. In addition, EPA city and highway fuel-economy figures are both up by 1 mpg (with a five-speed transmission).
- Technical Highlights
- A semi-trailing-arm suspension as new as the RX-7
by Csaba Csere
Suspension innovations are few and far between at most car companies, but they're regular occurrences at Mazda. The 19780 GLC was born with an intriguing multi-link rear suspension, and today's 626 benefits from an unusual asymmetry in its front suspension. Mazda engineers are currently studying four-wheel steering for future models.
With the new RX-7, Mazda has undertaken the noble task of eliminating the vices of the semi-trailing-arm rear suspension. In doing so, its engineers have created one of the most complex rear suspensions ever used in production, and one that bears only a vague resemblance to the original semi-trailing-arm design. Three new features have been added on each side: a double-jointed connection at the trailing arm's inner attachment point, an extra diagonal link, and a very complex mounting hub between the wheel and the trailing arm.
The purpose of the double-jointed connector is to split two key functions of the suspension hardware. It allows the trailing arm's inner member to manage wheel camber while the longer diagonal link provides excellent lateral location of the heel.
Mazda engineers have added the exotic hub to finish the job. Any suspension has some tendency to toe (steer) the rear wheels in and out under various acceleration, cornering , and braking forces, and Mazda has applied the special hub to use this natural tendency to best advantage. Located between the wheel carrier and the trailing arm, the hub consist of two flexible rubber bushings and one inflexible steel bearing, each of which acts as a combination mounting and pivoting point. Two of the pivots form an imaginary kingpin axis analogous to a front suspension's; the third performs a restraining function analogous to a tie rod's During normal running, the rear wheels point straight ahead to minimize tire wear and rolling friction, but under cornering loads, deflection of the semi-trailing-arm allow a slight amount (less than 0.2 degree) of tow-out. Mazda engineers feel that this sharpen the steering response by helping the car yaw (rotate about a vertical axis) more quickly. Excessive toe-out can cause instability, so at about 0.4g, the leader rubber bushing in the hub starts to deflect, causing the wheel to start toeing in. As cornering loads increase, toe-in reaches more than 0.5 degree, promoting understeer and enhancing stability.
Mazda's floating hub also produces toe-in during acceleration and braking. The aforementioned imaginary kingpin axis shifts in such a way that longitudinal forces cause the rear wheel to toe in slightly, increasing stability.
Other manufacturers will undoubtedly scoff at the complexity Mazda has gone to in the new RX-7 rear suspension, but that won't change this company's reluctance to accept old compromises when a new model is in the offing. At the very least, Mazda has shown that, with enough determination, even the 28-year-old semi-trailing-arm design can be taught a few new tricks.
The perfect sports car for the 80's
Mazda RX-7 Turbo II by Rick Titus -- Motor Trend -- September 1987
Control, comfort, speed, and image, the core of today's sports cars, are all in the makeup of the RX-7 Turbo II, and outstanding, well-engineered automobile. It's sleek, fast, and externally understated. No flash, no fluff, no fake. This is the sports car real sports car lovers drive.
As a second-generation RX-7, the Turbo II is an evolutionary incarnation of the first RX design. Cleaner, smoother, and certainly more current-looking than its predecessor, the familiar RX-7 shape is still there, but the platform as a whole is greatly improved. Turbocharged and intercooled for the first time, the 13B twin-rotor engine produces 182 hp, for which its 15.49-sec quarter-mile time speaks quite highly. Performance, both in terms of speed and handling, is the foundation on which the RX-7 is built. Calm and easy to drive in street traffic, the Turbo II becomes a driver's car when turned loose.
The RX-7's ride is stiff, yet proved quite tolerable in day-to-day use. The supportive bucket seats would profit from just a bit more padding for the long hauls, but, in total, driver/passenger comfort is good. AS for ergonomics, the RX-7 has the best-placed instruments and switches of any car from Japan. The dashboard design isn't "high-tech" in appearance, but, in practice, remains true to the "driver's car" theme. Two large, oval analog instruments faces make up the tach and speedo. Oil pressure, water temp, fuel level, and boost pressure gauges complete the Turbo II instrument package. Headligh, cruise control, wiper/washer (front and rear), good rear window defroster, four flashers and directional signals are all placed at finger's reach without the requirement of removing your hands from the steering wheel. A very tidy piece of engineering.
The Turbo II has a split personality. In its bumper-to-bumper to-the-office-and-back traffic mode, it's light to the touch, undramatic, and easy to live with. In its twisty back-road mode, it's a foot-to-the-wood hellraiser. Stable, predictable, fast, and sure, it arrives at every corner in a hurry, points in well, tolerates a bunch of late braking, encourages trailing throttle entries, and possesses a mild, yet throttle-controllable, understeer. IN short, it's the perfect-mannered sports. Car. Of all the Turbo II's excellent handling traits, its reaction (or lack of it) to mid-corner throttle adjustments impresses us most. Much has already been made of a Mazda's patented Dynamic Tracking Suspension System (DTSS), a passive system that actually permits the rear wheels to have a toe-steer influence during cornering. But many expressed concern about the long-term reliability of the system, for fear that its series of links and bushings would wear, causing the rearend alignment to change with age. Fear not; to date, all service reports are favorable.
As with all Mazda rotaries, the Turbo II needs to be driven hard to extract its full potential. Slow to rev on the bottom end, it lights like an exploding firecracker once on the turbo. Mid-range power is nothing short of wonderful, making a Corvette-eater out of it in 3rd and 4th gears. There is a leaning curve to this power when it comes time to apply it in a corner. Too much at the wrong time finds the tail end looking for a home somewhere north of the front end if you're not careful. A discreet and progressive feed of throttle matched to platform speed makes a race driver out of any skilled enthusiast. The chassis responds quite well to driver input, though the steering feels a tad mute on center. Once steering effort is induced, the feedback is accurate and informative. The brake pedal remains firm, even after repeated hard stops. Decelerating from 60-0 in less than 136 ft. gives the Turbo II top marks in the getting slowed division.
The hood slope is steep, making the top of the intercooler scoop the reference point to the front end. Side visibility is good for this type of car, but the seating position puts you low to the window sills, so it takes a few miles behind the wheel to come to a comfortable reference with the entire car. Once acclimated, though, the feel is reassuring and sporty. The 2-seat sports car marketplace has changed a great deal in the last10 years. Today's consumer isn't looking for driveway oil stains and roulette-wheel reliability. Gone are leaky side curtains, mono-speaker AM radio, buckboard ride, lethargic acceleration, and unpredictable handling. Today's sports cars are required to have comfort controlled environments, premium sound systems, taut but reasonable ride harshness, lightning performance, and razor-sharp handling. Today's sports car are more than just weekend toys. They're real-world broad-based day-to-day transportation. And; to that end, the current market is filled with an outstanding selection. Chevrolet (Corvette), Porsche (944/911), Pontiac (Fiero GT), Toyota (MR2), and Honda (CRX Si) build strong competition.
Since it won our 1986 Import Car of the Year award, the car's price has rapidly escalated. AT $21,000 base, Mazda's RX-7 Turbo II isn't for everybody. Even at that lofty price, however, it represents a very good value. It's solid quick, safe, and good looking. And, best of all, it fits today's sports car requirements to the tee.
- Second Opinion by Daniel Charles Ross
When Mazda relinquished to me the keys to a lethal-looking jet-black RX-7 Turbo II, I approached the car as anyone might for a pre-purchase familiarization. Its anointment as our 1986 Import Car of the Year came before I arrived onboard, and I had, somehow, never drive one. I was most eager to spend some days in the car because I had no preconceived notions percolating about it.
I like its sports-car feel. The passenger cell is as snug as a Mercury space capsule, and the seats were decent in terms of comfort and adjustment. Controls are readable and reachable and instrumentation is complete. An aggressive exterior fairly shouts the RX-7's basic hormonal appeal, but I think it amounts to mask concealing a truer real-world nature.
Driving it producing no lasting boil, only a light simmer flashed with occasional adrenal outbursts. It likes higher rpms for best performance, because that's where the power lives. Unfortunately, due to turbo lag, stoplight-defeating low-end torque is absent unless one abuses clutch engagement. High-speed driving is fun—especially in this particular car—but, let's face it, most drivers spend a high-performance lifetime shuttling to and from work. And the commute isn't where this car shines.
The RX-7 Turbo II isn't able to promote its full potential driven with traffic. To get full value for the money, it must be drive with abandon.
The Second-Generation Mazda RX-7: Beauty, Practicality, Performance, and a Race-Winning Platform
Story by Tim Suddard
Grassroots Motorsports May/June 1998 Volume 15 Number 3
Between the furor of the first generation Mazda RX-7 and the high-tech wonder that was the last incarnation of the famous model lies an almost forgotten masterpiece: the second-generation RX-7. Why was this car, with its sub-nine-second 0-60 times, refinement and good looks, forgotten? Good question. On paper, on the street and on the racetrack, the second-generation RX-7 – built between 1986 and 1991 – still makes a lot of sense for the budget-minded enthusiast.
This magazine compared a then-new RX-7 to its predecessor, the RX-7 GSL SE in 1986 and we came away impressed with the second-generation car. Racers, however did not embrace this car as they had the first-generation RX-7. Perhaps this was due to the newer car’s larger size, high price (at the time) and less than optimum autocross classing. The import drag explosion had not really happened yet either – kids seemed to be concentrating on Buick Grand Nationals and 5.0 Mustangs.
Today, the second-generation RX-7 is seeing somewhat of a revival. Spurred on by ridiculously low prices and increased popularity in the SCCA’s Improved Touring racing, these cars are a 10-year-old overnight sensation.
You do need to address some question before rushing out and buying one, though: Which RX-7 should you look for? What goes wrong with them? And how should you modify them for street or racetrack use?
Follow along as we review the breed and study the strengths and weaknesses. We’ll also talk to experts like SpeedSource’s Sylvain Tremblay, who has turned one of these cars into arguably the fastest Improved Touring cars in the world.
- First, a Little History
At the end of a rough first decade in the U.S. Mazda finally hit a big-time home run in the spring of 1978 with the introduction of the Mazda RX-7. However this "revolutionary" car was really anything but. Essentially it was the same 12A rotary engine from Mazda’s RX-3 sedan mated to a five-speed transmission and live rear axle. Brakes were disc at front and drum at the rear, the optional rear disc brakes and limited-slip differential were not offered until 1981 as part of the GSL package. Steering was not even rack and pinion.
Still, the RX-7 worked. It looked right, ran well, and in the hands of autocrossers and road racers around the nation it captured many wins and championships. The RX-7 began to redefine the idea of a sports car for the masses.
By 1984, the cry was out for more power and more modernization. Mazda answered with the introduction of the RX-7 GSL SE. This car came equipped a fuel-injected version of the RX4’s 13B rotary Rated at 135hp, this engine had a third more power than the 12 A that powered the original RX-7.
With bigger wheels, more luxurious options and a more complicated induction system, the GSL SE was more than 200 pounds heavier than its predecessor, so performance was not that startling. Many autocrossers opted to stay with their earlier cars, especially considering the more favorable classing of those 12A-powered RX-7s.
- The Second-generation Car
In 1986, Mazda introduced an entirely new RX-7. This second-generation car shared very little with earlier cars: gone was the small distinctive shape that was the first RX-7. In its place was a decided attempt to move upmarket into Porsche 944 territory.
The styling was still very clean, but there were many who considered it somewhat bland and unimaginative compared to the original car. There was no doubt, however that the second-generation car was much improved in every area. The cover story in this magazine’s March 1986 issue (then called Auto-X) compared the new verses old RX-7. In back-to-back autocross testing, we determined that the new RX-7 was faster all around the course. It was also faster in a straight line, with 0-60 times in the eight-second range – a full second faster that the first car.
In addition to the all-new shape and body work, there were many other changes to the new RX-7 – so many changes in fact, that the new car probably should have been called an RX-8. (Mazda was not that stupid; the company would play upon the success of the first –generation RX-7 name when introducing the new car.) Up front, aluminum replaced steel in the hubs and A-arms, while rack and pinion steering finally replaced the somewhat numb recalculating ball of the older cars.
At the rear came the big news. Gone was the live axle of the early cars and in its place was a very sophisticated (some say too sophisticated) fully independent suspension system, which Mazda dubbed DTSS (Dynamic Tracking Suspension System).
Most of the Japanese car builders had become fascinated with four-wheel steering in the mid-80’s, and DTSS was essentially Mazda’s attempt at a passive 4ws chassis. This system featured a "Tri-axial Floating Hub" and an extra link which reduced the toe-out common to semi-trailing arm rear suspensions. Interestingly, the system was only designed to come into play above 4g of cornering force. In practice, this meant it was fine for the street, but would make for some pretty scary handling on a racetrack.
Four-wheel-disc brakes were now standard on the car, while the GXL and sport model cars came with four-piston, finned alloy calipers.
The new RX-7’s engine was also different, even compared to the 13B-powerd 1984-’85 GSL SE. Horsepower was up to 146 at 6500 rpm, thanks to improved fuel injection and lighter engine rotors. Other parts of the engine were also updated, including the motor mounts and the actual rotor housings them selves. In effect, the 1986 engine was pretty much totally new.
Naturally, the interior was also completely redesigned and shared very little with the earlier cars.
The car was introduced in base trim as well as a more upscale GXL model. The GXL was equipped with the aforementioned better brakes, plus more luxurious appointments. GXL cars also were fitted with 15-inch wheels (versus the 14-inch wheels on base models) and 205/60-15 tires. The sports package available on either model featured the larger tier size as well as stiffer springs and shocks.
Another option was 2+2 seating, although these back seats were a token. The standard storage bins that were offered instead of rear seats were probably of greater value.
- RX-7 Turbo
Shortly after the car was introduced in the winter of 1986, Mazda blew everyone away with the announcement of a turbo version, set to be introduced as a 1987 model. This modification turned the new RX-7 from a very competent sports car into a bonafide super car.
Mazda called the car the Turbo, but dubbed the engine the Turbo II. Although it was the first turbo rotary Mazda in this country, Mazda had offered a turbocharged 12A earlier in Japan. Horsepower with the turbo was up to 182, despite boost, which was restricted to five to six pounds depending on rpm. The turbo was also equipped with a beefier five-speed transmission (automatic was not offered) and a stronger rear end. The turbo-charger itself was built by Hitachi and named the HT18-2S.
The only other real news for 1987 was the option of anti-lock brakes on GXL and turbo models.
1988 saw the introduction of the convertible version in non-turbo form only. Although slick and good-looking, this conversion added some 378 pounds to the RX-7, thus turning the convertible into a boulevard machine.
Also introduced in 1988 was the GTU version of the RX-7. The GTU was the sports version, named to honor Mazda’s wins in IMSA’s GTU category. This model came with 15x6-inch alloy wheels (as did the GXL), a limited-slip differential, sport suspension, a body kit, body-colored door mirrors and sport seats.
Also new for 1988 was the SE name (which indicated a base model). The GXL, remained the luxury version with all the toys like power windows, cruise control and sunroof.
Major Changes came in 1989 with the introduction of another new model. The GTU became the base model, while the new GTUs became essentially a turbo version without the turbo. This no-nonsense machine had the upgraded suspension and all the performance goodies without all the luxuries that added weight. It even had a 4.30:1 rear end (compared to the standard 4.10:1 unit). Apparently not many people (other than us) thought this was a cool idea, as only about 100 were built.
There were no real changes for 1990, except the convertible got an airbag. In 1991, the last year for these great cars, the model lineup was simplified to coupe, convertible and turbo. All the cars were extensively optioned, so there was no more base model.
- What Goes Wrong
Mazda RX-7s have never been known as bad rusters, but even these second-generation cars have their spots. If the rear hatch drain holes get plugged, the rear hatch area gets rusty pretty quickly. The cars also tend to rust around the doorjambs, so check these carefully.
These cars have front subframes and are very difficult to get straight once they have been in an accident. Also, the nose cone (roughly $800) and taillights are expensive, so check these pieces carefully.
The much-maligned rotary engine really was nearly bulletproof by the mid-‘80s, and a well cared for engine is good for 200,000 miles. Like most cars, oil needs to be changed regularly. Overheating is to be strictly avoided, and never shut a hot turbocharged car without first letting it cool. Look for evidence of this type of sympathetic care when seeking out a car to buy.
One real Achilles’ heel on these cars is the eccentric shaft bypass valve. This valve lubricates the oil seals and o-rings, but only after the engine heats up. If it fails, you won’t know it until the engine stars to smoke, and by then it’s too late. Most premature engine failures can be attributed to either this problem, over-heating or abuse.
The solution is to replace this item as a matter of course (as you would an air filter element) ever 75,000 miles or so. Tri-Point Engineering highly recommends this service and charges $235 for parts and labor.
- RX-7s in Competition
Most of Mazda’s competition success with the RX-7 was with first-generation cars. However, there are some notable exceptions. Pierre Honegger got a couple of wins in the old IMSA Firehawk Street Stock series in 1987 with a normally-aspirated car, while a highly modified car was run in IMSA’s GTO category by Roger Mandeville and others. Don Sherman (of Car and Driver) and his team set a world speed record at Bonneville with a second-generation car as well.
Rod Millen finished second in the points (behind Buffum’s Audi) in SCCA PRO Rally in 1986. He also took a run at Pikes Peak, but didn’t win.
Mark Schuler and Craig Nagler of Tri-Point Engineering probably had the most success competing in second-generation RX-7s. They autocrossed an ex-Playboy Cup car in F prepared through much of the early ‘90s, racking up an impressive string of victories. IN Pro Solo, Schuler took the series championship in 1991, while co-diver Nager took it in ’92, ’93, and ’94. They won the Solo II National Championships in ’92, ’93 and ’94. After the ’94 season, they sold the car to Debbie Eley, who also has done well with the car.
- Modifying for the Street
Most experts agree that for the street or local autocross competition, you don’t need to do much to these cars. A rotary, more than just about any other type of combustion engine, is a large air pump. Open up each end, and magical things start to happen. With electronic fuel injection on the intake side of things, the easiest thing to do is change to a performance chip. Companies such as GRreddy and HKS have made these chips for years, and Carl Sloan of SAS has introduced a chip that he claims adds 30 horsepower and 46 ft.-Ibs. of torque on the dyno. On the other hand, some rotary experts say they haven’t had such good luck with chips.
On a rotary engine, the exhaust is also very crucial. While exhaust changes can make a five to 10 horsepower difference on a piston-engined streetcar, it is not uncommon for exhaust changes to make a 30-horsepower improvement on a rotary-powered streetcar. High-flow catalytic converts help, as does enlarging and tuning the exhaust.
For better torque, run two long, straight pipes as far as you can. For maximum top end, you will want to add a crossover pipe in your system. Be aware that rotaries are insanely loud and exhaust temps should be in the 1600-1800 degree area, so play safe when messing with exhaust. Most of the companies listed in the source box sell a street exhaust for these cars.
In the area of handling, all the experts agree that the factory three-position shocks are the weak link on these cars. A good, quality shock setup (preferably adjustable coil-over) is a must. Mark Schuler of Tri-Point Engineering runs Penskes, while Sylvain Tremblay modifies Koni units.
A common mistake people make with these cars is to slap big tires and wheels on them. These are designed to work best in the 6000-7200 rpm range, so the 4.10:1 or 4.30:1 stock gears ratios, combined with the original-equipment 205/60-15 size tires, offer a pretty good setup.
When choosing a car, the early non-turbo models are more desirable that the later ones. If you are looking for a turbo car, go for late on, specifically the 1989-and-up twin-scroll turbo car. In addition to featuring 18 more horsepower, its revised intake manifold and turbo system make for amore drivable and reliable car.
A notable exception to the preceding rule is the GTUs. Although very few were built, Mark Schuler of Tri-point feels that this would be the ultimate non-turbo second-generation, thanks to its lightweight, turbo chassis and later high-compression engine.
- Building an IT RX-7
At last year’s ARRC, the national championship for SCCA Regional classes, Sylvain Tremblay set the enduro pole, while his co-driver, David Haskell, set the sprint race pole in the SpeedSource 1989 RX-7 GXL. We sat down with Sylvain, who built this and many other second generation RX-7s from the ground up in his shop, SpeedSource, and asked him for some of his secrets.
The first thing he said is that you want to start with a 1986-’88 RX-7 GXL. Why? Because these models already have the five-lug hubs and four-piston front and vented rear brakes. Another sizable advantage is that the early cars are plentiful and roughly half the price of the later cars. The best of both worlds would be to have an early car with a 1989-and-up high-compression engine.
The 1989-and-up cars have disadvantages: First, they have those annoying motorized seat belts (passive restraints) which add weight. Also, the dash assembly in it is 35 pounds heavier.
Sylvain looks for non-power steering car, which is some 25 pounds lighter. You also want crank, not power, windows (five to six pounds saved per door) and no sunroof (headroom problems and 22 pounds way up high, where you don’t want it).
The RX-7 has immense door openings, which sacrifice structural rigidity. The front end of the car is strong, though, because of the aforementioned front subframe. You want to design a cage that stiffens the unibody around the massive door openings. Use two door bars. Go to the side rails, not the floor, to mount the feet. Make sure you got the floor box rocker, and for extra safety, get as close to the roof as you can get because it’s quite thin.
As far as suspension goes, Sylvain advises against the stock RX-7 shocks or any standard aftermarket items for the RX-7. They will not hold up and will overheat when combined with the rigors of IT racing and the stiff springs needed to make the big RX-7 handle well. When the shocks get hot, the handling will just fade away. He recommends and runs aluminum coil-overs from Koni. He has had them specially modified for RX-7s. Spring rates should be in the 300-400 Ib. rate up front and 200-275 Ib. rate at the rear. Naturally, this depends on diver size and preference.
For anti-roll bars, Sylvain has designed an adjustable torsion bar that is similar to the bars used in SCCA Trans-AM and NASCAR. Sylvain claims that this style of bar offers more consistency and, since it’s hollow, lighter weight. He sells a .250-wall bar with heim-jointed ends for about 90 percent of all applications. Thinner-wall bars are also available.
Top-mounted camber plates are also a necessity on an RX-7, as they allow more wheel travel. Another trick Sylvain has designed is a chamber link that tilts the entire rear suspension upward. This counters the added negative camber that lowering springs create. The rest of the rear subframe bushing are kept stock, as aftermarket bushing are expensive and Sylvain has found no performance advantage to changing them.
Sylvain likes to neutralize the rear steer designed into the Mazda RX-7 rear suspension with special toe control bushings that he has created. The 4ws system designed into an RX-7 has its good points, but in a racing situation it is difficult to control. The result is squirrelly handling. Disabling the 4ws restores predictable response.
As far as brakes go, Sylvain does not recommend splitting the calipers, because you will never get them back together as good as they were. You need to clean out the crossover passages between the calipers thoroughly, though, for best braking. He recommends Motul brake fluid and Hawk Blue pads all the way around for racing. A lever-style brake-proportioning valve is also advised. Knob types are too confusing to use when racing.
Rotaries do not tolerate overheating, not even a little, so the cooling system is very important. Speedsource has had special Griffin aluminum cross-flow radiators made to fit. They also run a twin oil cooler with high-pressure hoses. Sylvain suggest running the coolers in parallel, not in series, as there is less oil pressure drop.
Much of a rotary’s power is made by improving the exhaust. The collector’s design, size and location directly affect torque, throttle response and top end. Speedsource sells an exhaust system that maximizes power for IT racing.
Speedsource ran Toyos tires on their IT cars for years, but last year they switched to the new Hoosier radials. They run the 225/45-15 tires on a 15x7-inch wheel (the maximum wheel size allowed for IT racing). Sylvain adds that Hoosier tires are mush light. This coupled with state-of-the-art compounds, is an advantage that computes to about 7/10ths to 8-10ths of a second faster on the average track, he says. However, Sylvain has found that you have to learn the Hoosiers. They are easy to flat spot, which means an expensive learning curve. Once you figure them out. Sylvain says you will have no problem with them.
Sylvain uses wheels with five inches of back spacing. He believes that you need six strong, relatively inexpensive wheels for enduro racing and four super-light but perhaps not as durable wheels for sprint racing and qualifying. They use Weld wheels.
Last, but not least, comes the engine. IT rules do not allow much engine modification, so Sylvain carefully balances engine parts to the lightest part. You also need to regulate the oil pressure to about 95-100 psi. A good rule of thumb for rotaries is to have 10 psi for every 1000 rpm you wish to run. The stock computer shuts the engine down at 7700 rpm, but the stock engine stops making power at 7500 rpm anyway. The optimum exhaust temperature for a rotary is about 1650 degrees Fahrenheit.
Naturally, SpeedSource, as well as several other advertisers in this publication can supply you with most of these parts as well as complete engines or turnkey cars ready to race.
These cars stayed rather expensive until just recently. If you check the Autotrader Web Site, (www.traderonline.com) you will find that there are more than a 100 of these cars for sale at any one time all over the country.
Early cars range from about $750 for a rat, or one with engine problems (nothing kills a car’s value, especially a rotary’s, like engine problems) to about $6000 for absolute low-mileage cream puffs. The average seems to be in the $2000-$3000 range for good, useable cars. The later cars will run more, but it looks like you can still get a decent late car for $5000-$6000. Late turbos and convertibles will run more.
These cars are well designed, great looking, somewhat practical and offer the enthusiast a great platform for a fun street toy or a really competitive racecar.