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MM Retro Write-Up: 1993-1995 Mazda RX-7
IN A NUTSHELL: A Japanese Colin-Chapman-mobile
Mazda was not the first the first auto manufacturer to actually use the Rotary (Wankel) engine, which had been invented in Germany by Felix Wankel, working for the German NSU Motorenwerke AG. They were, however, arguably the first company to attempt, under license, to market a production sports car with it (the Cosmo from the 1960s), and the later RX-7, starting in 1978. Some experimental versions of the Miata were done with rotary engines, but never put into production. For the purposes of this write-up, I’ll skip the first two versions of the RX-7, and concentrate on the well-known Third-Generation model, because it was the version that was most highly-respected by the auto press and enthusiasts, despite some deficiencies in its design and durability.
But, first, for those of you who are not familiar with rotary engines, I’ll give a short description. Rotary engines are called rotary because they do not have conventional blocks, pistons, connecting rods, valves, or a crankshaft. Instead, a more or less triangular-shaped rotor spins around inside a small lightweight aluminum case, with a chamber that has a very slight figure-eight shape to it. As the rotor spins around, it forms three separate chambers, where one chamber draws in the air/fuel mixture through a port (not a valve), the next chamber fires off the air/fuel mixture with a set of double-spark plugs, and the third chamber expels the burnt exhaust-gas through another port. A gear-like attachment on the output shaft, which the rotor spins around, sends the power back to the transmission. This relatively smooth operation, without the inherent up-and-down motions of pistons and crankshafts, enables the engine to spin at very high RPMs, almost comparable to a motorcycle engine, with very little vibration….rotary engines have unusually high redlines on the tach. This allows a very high horsepower-to-weight ratio from a small displacement, though torque tends to suffer at low RPMs…..sometimes markedly. Rotary engines, by their design, also tend to have high fuel consumption because the rapidly-spinning rotor is more frequently drawing in fuel and air from the ports every revolution, instead of only on a the intake-stroke like a conventional four-stroke reciprocating engine. Rotary-engine owners learn to carry a extra can of engine oil with them in the trunk. Oil consumption and engine wear is also a problem, because the engine burns a very small amount of its own oil with each rotor-revolution (to pass emissions-tests, that oil-burning has to be cleaned up in the exhaust with advanced catalysts). Since there are no piston rings in a rotary engine, a set of what are called apex-tip seals more or less takes their place….these seals were long a durability issue, and, though improved over the years, were never really perfected, even in the advanced non-turbo Genesis rotary used in the later RX-8.
So, the rotary engines were not the most durable or reliable of designs, and, because of their uniqueness in very few vehicles, service and replacement parts could be expensive in dealer parts-departments. They also sometimes had a nasty tendency to flood on a cold start, particularly earlier versions with carburetors, and could emit a big cloud of smoke covering the entire area (I’ve seen this happen myself on some occasions). In short, they were a great idea that, sadly, never really got perfected, despite the fact that they were a natural for some sports cars, and easily gave designers an almost perfect 50/50 balance for ideal RWD handling. They also took up very little space under the hood, which allowed for a low hood line and low center of gravity to further enhance stable handling.
OK….back to the RX-7. like I said, I’ll skip the first two versions, as, IMO, the first generation was clearly the best-built of the three and used the best materials, but IMO was not particularly exciting, and I didn’t care for its wedge-shaped front end.. The second-generation, IMO, was a little more sharply-styled, but lost some of its built/material quality.
The third-generation version, introduced late in 1992 as a 1993 model, lost even more of its build/material quality, but it was an absolute hoot to drive in sports-car conditions…particularly if you didn’t mind light/cheap materials all around you. The competing Toyota Supra, Nissan 300ZX, Dodge Stealth, and Mitsubishi 3000GT all had more power and sophistication, but were also heavier, bulkier, had a lot more parts, and just didn’t have the same feel.
The 3rd-generation RX-7, with its extremely lightweight platform/chassis (though larger, comparable in some ways to the way Lotus products were built using Colin Chapmans philosophy) Twin-Turbo rotary engine, and Go-Kart handling characteristics, was simply in a class by itself. I did not own one, but sampled a couple of them on test-drives on a number of different surfaces. The front end would respond almost by breathing on it. It would hold the tightest/sharpest curve like on rails…and just as quickly flip to cornering in the other direction. In short, along as the surface was dry (all else equal, sports cars like this generally don’t do well in rain or snow because of RWD and tire-characteristics), it was exceedingly difficult to really in get in trouble with this car in a winding road unless you did something really stupid, and not worthy of having a driver’s license in the first place.
But there were some down-sides and penalties for that oversized Go-Kart handling….in addition to the usual rotary-engine problems I described above. To achieve that Colin-Chapman-style of handling/acceleration, very light materials were used in the RX-7’s body and chassis….usually from very light-grade aluminum. That meant weakness and durability issues in sometimes important underbody components. Hit anything more than a very minor pothole or spot of bad pavement, and you could bend or warp a suspension or steering component…..these cars were often in the shop for underbody repairs. That meant you had to try and stay on glass-smooth roads if possible. Even on smooth roads, though, particularly with porous or grainy-surface paving, the marked lack of weight-adding sound insulation meant that tire-roar was loud and excessive….best to invest in a set of ear plugs and just forget listening to the stereo. Expansion-joints usually came through as loud thuds. Any ice or slick surfaces?….best to keep it in the garage. And, of course, for American-sized large males, like with most small 2-seat sports cars, it usually meant difficult entry/exit, cramped quarters inside, and little cargo space.
The third-generation RX-7, like the other Japanese competitors I listed above, became the victim of steadily-increasing prices, insurance-premiums, and tightening CAFE rules/emissions requirements, where the rotary engine’s inherent weaknesses put it at a market-disadvantage against even those Supra/300ZX/Stealth/3000GT competitors. All of them had been pulled out of the American market by the late 1990s, and Mazda pulled the plug on the American-spec RX-7 after 1995….only two years of production here. While, for a number of reasons, none of these were vehicles that I would care to own, I was genuinely sorry to see them go. At the D.C. Auto shows of the mid-1990s, I suggested, several times, to reps from these companies, that, instead of simply dropping them altogether (which they were planning to do at that time), simply address the price/insurance problems by decontenting the cars some and cutting the prices…the 3000GT VR-4, for example, had (for the time) a tremendous level of features, sophistication, and complexity to it. Went in one ear and out the other, though….all of these sports cars were yanked out of the American market by the late 90s, although some of them were indeed to return to the U.S. several years later (as I had suggested) in simpler, cheaper versions, like the Nissan 350Z, Mazda RX-8, and (just recently) a joint BMW/Toyota-designed Supra. And the RX-7 itself carried on in overseas markets until 2002.
So, in the U.S., the 1993-1995 RX-7 was perhaps the epitome of the Japanese sports car designed to the Lotus/Chapman-school of thought (lighter is better)……unless , of course, it results in bent or broken parts. For many reasons, we will not likely see anything quite like it again in the gasoline-fueled-world of street-vehicles. Recent advances in electric-motor technology has resulted in small, light, powerful electric motors and their extreme low-RPM torque (drive a Tesla Model 3 if you want proof), but the large heavy battery-packs for those vehicles, even if mounted low, add weight and can disrupt the center of gravity for handling.
And, as Always, Happy Vehicle-Memories.
MM
__________________
DRIVING IS BELIEVING
IN A NUTSHELL: A Japanese Colin-Chapman-mobile
Mazda was not the first the first auto manufacturer to actually use the Rotary (Wankel) engine, which had been invented in Germany by Felix Wankel, working for the German NSU Motorenwerke AG. They were, however, arguably the first company to attempt, under license, to market a production sports car with it (the Cosmo from the 1960s), and the later RX-7, starting in 1978. Some experimental versions of the Miata were done with rotary engines, but never put into production. For the purposes of this write-up, I’ll skip the first two versions of the RX-7, and concentrate on the well-known Third-Generation model, because it was the version that was most highly-respected by the auto press and enthusiasts, despite some deficiencies in its design and durability.
But, first, for those of you who are not familiar with rotary engines, I’ll give a short description. Rotary engines are called rotary because they do not have conventional blocks, pistons, connecting rods, valves, or a crankshaft. Instead, a more or less triangular-shaped rotor spins around inside a small lightweight aluminum case, with a chamber that has a very slight figure-eight shape to it. As the rotor spins around, it forms three separate chambers, where one chamber draws in the air/fuel mixture through a port (not a valve), the next chamber fires off the air/fuel mixture with a set of double-spark plugs, and the third chamber expels the burnt exhaust-gas through another port. A gear-like attachment on the output shaft, which the rotor spins around, sends the power back to the transmission. This relatively smooth operation, without the inherent up-and-down motions of pistons and crankshafts, enables the engine to spin at very high RPMs, almost comparable to a motorcycle engine, with very little vibration….rotary engines have unusually high redlines on the tach. This allows a very high horsepower-to-weight ratio from a small displacement, though torque tends to suffer at low RPMs…..sometimes markedly. Rotary engines, by their design, also tend to have high fuel consumption because the rapidly-spinning rotor is more frequently drawing in fuel and air from the ports every revolution, instead of only on a the intake-stroke like a conventional four-stroke reciprocating engine. Rotary-engine owners learn to carry a extra can of engine oil with them in the trunk. Oil consumption and engine wear is also a problem, because the engine burns a very small amount of its own oil with each rotor-revolution (to pass emissions-tests, that oil-burning has to be cleaned up in the exhaust with advanced catalysts). Since there are no piston rings in a rotary engine, a set of what are called apex-tip seals more or less takes their place….these seals were long a durability issue, and, though improved over the years, were never really perfected, even in the advanced non-turbo Genesis rotary used in the later RX-8.
So, the rotary engines were not the most durable or reliable of designs, and, because of their uniqueness in very few vehicles, service and replacement parts could be expensive in dealer parts-departments. They also sometimes had a nasty tendency to flood on a cold start, particularly earlier versions with carburetors, and could emit a big cloud of smoke covering the entire area (I’ve seen this happen myself on some occasions). In short, they were a great idea that, sadly, never really got perfected, despite the fact that they were a natural for some sports cars, and easily gave designers an almost perfect 50/50 balance for ideal RWD handling. They also took up very little space under the hood, which allowed for a low hood line and low center of gravity to further enhance stable handling.
OK….back to the RX-7. like I said, I’ll skip the first two versions, as, IMO, the first generation was clearly the best-built of the three and used the best materials, but IMO was not particularly exciting, and I didn’t care for its wedge-shaped front end.. The second-generation, IMO, was a little more sharply-styled, but lost some of its built/material quality.
The third-generation version, introduced late in 1992 as a 1993 model, lost even more of its build/material quality, but it was an absolute hoot to drive in sports-car conditions…particularly if you didn’t mind light/cheap materials all around you. The competing Toyota Supra, Nissan 300ZX, Dodge Stealth, and Mitsubishi 3000GT all had more power and sophistication, but were also heavier, bulkier, had a lot more parts, and just didn’t have the same feel.
The 3rd-generation RX-7, with its extremely lightweight platform/chassis (though larger, comparable in some ways to the way Lotus products were built using Colin Chapmans philosophy) Twin-Turbo rotary engine, and Go-Kart handling characteristics, was simply in a class by itself. I did not own one, but sampled a couple of them on test-drives on a number of different surfaces. The front end would respond almost by breathing on it. It would hold the tightest/sharpest curve like on rails…and just as quickly flip to cornering in the other direction. In short, along as the surface was dry (all else equal, sports cars like this generally don’t do well in rain or snow because of RWD and tire-characteristics), it was exceedingly difficult to really in get in trouble with this car in a winding road unless you did something really stupid, and not worthy of having a driver’s license in the first place.
But there were some down-sides and penalties for that oversized Go-Kart handling….in addition to the usual rotary-engine problems I described above. To achieve that Colin-Chapman-style of handling/acceleration, very light materials were used in the RX-7’s body and chassis….usually from very light-grade aluminum. That meant weakness and durability issues in sometimes important underbody components. Hit anything more than a very minor pothole or spot of bad pavement, and you could bend or warp a suspension or steering component…..these cars were often in the shop for underbody repairs. That meant you had to try and stay on glass-smooth roads if possible. Even on smooth roads, though, particularly with porous or grainy-surface paving, the marked lack of weight-adding sound insulation meant that tire-roar was loud and excessive….best to invest in a set of ear plugs and just forget listening to the stereo. Expansion-joints usually came through as loud thuds. Any ice or slick surfaces?….best to keep it in the garage. And, of course, for American-sized large males, like with most small 2-seat sports cars, it usually meant difficult entry/exit, cramped quarters inside, and little cargo space.
The third-generation RX-7, like the other Japanese competitors I listed above, became the victim of steadily-increasing prices, insurance-premiums, and tightening CAFE rules/emissions requirements, where the rotary engine’s inherent weaknesses put it at a market-disadvantage against even those Supra/300ZX/Stealth/3000GT competitors. All of them had been pulled out of the American market by the late 1990s, and Mazda pulled the plug on the American-spec RX-7 after 1995….only two years of production here. While, for a number of reasons, none of these were vehicles that I would care to own, I was genuinely sorry to see them go. At the D.C. Auto shows of the mid-1990s, I suggested, several times, to reps from these companies, that, instead of simply dropping them altogether (which they were planning to do at that time), simply address the price/insurance problems by decontenting the cars some and cutting the prices…the 3000GT VR-4, for example, had (for the time) a tremendous level of features, sophistication, and complexity to it. Went in one ear and out the other, though….all of these sports cars were yanked out of the American market by the late 90s, although some of them were indeed to return to the U.S. several years later (as I had suggested) in simpler, cheaper versions, like the Nissan 350Z, Mazda RX-8, and (just recently) a joint BMW/Toyota-designed Supra. And the RX-7 itself carried on in overseas markets until 2002.
So, in the U.S., the 1993-1995 RX-7 was perhaps the epitome of the Japanese sports car designed to the Lotus/Chapman-school of thought (lighter is better)……unless , of course, it results in bent or broken parts. For many reasons, we will not likely see anything quite like it again in the gasoline-fueled-world of street-vehicles. Recent advances in electric-motor technology has resulted in small, light, powerful electric motors and their extreme low-RPM torque (drive a Tesla Model 3 if you want proof), but the large heavy battery-packs for those vehicles, even if mounted low, add weight and can disrupt the center of gravity for handling.
And, as Always, Happy Vehicle-Memories.
MM
__________________
DRIVING IS BELIEVING