Road and Track Article VERY INTERESTING!
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Road and Track Article VERY INTERESTING!
Heres a R&T article you may find interesting.....
Technology Update: Renesis Rotary
Mazda reinvents the Wankel—again
By Douglas Kott
“The piston engine goes boing, boing, boing, boing, boing—but the Mazda goes hmmmmm.” Remember Mazda’s admittedly cornball 1970s’ TV ad? Complete with a kid on a pogo stick embodying the evils of pure reciprocating movement, the spot touted the smoothness of this novel powerplant that melds the Otto cycle’s four events of intake, compression, power and exhaust with a rotating motion. Like the Porsche 911’s air-cooled flat-6 or Saab’s quirky 2-strokes, the Wankel will be forever linked with Mazda, as it has twirled beneath the hoods of RX-2s, RX-3s, three generations of RX-7s—and even, for the Japanese market, a 26-passenger bus called the Parkway Rotary—for more than three decades.
Yet the concept was dreamed up—quite literally—in the summer of 1919 by a 17-year-old German boy, Felix Wankel. In his dream, Wankel drove a car of his own construction to a concert, where he even remembered boasting to his friends, “My car has a new type of engine: a half-turbine, half-reciprocating engine. I invented it!” Wankel succeeded in turning his vision into hard prototypes, at first with the German government and later with NSU, which first built a Wankel-type supercharger that enabled its 50-cc motorcycle to set a world speed record of 122.7 mph in the mid-1950s. NSU ultimately focused on four wheels, building a single-rotor 2-seat roadster called the Wankel Spider in 1963, followed by the homely Ro 80 2-rotor sedan of 1967.
Both GM and Mercedes-Benz took long, hard looks at the rotary’s viability. But it was Mazda, largely through the engineering brilliance of Kenichi Yamamoto, that refined the design and made the rotary engine a reliable, mass-produced reality. Since the Japanese introduction of the Mazda Cosmo Sport roadster in 1967, Mazda worldwide has sold more than 1.8 million rotary-powered cars, trucks…and the occasional bus.
Sadly, the last U.S.-market RX-7 blinked its taillights goodbye in 1996. Why did that sports car, practically deified by the automotive press including Road & Track, go away? Partly because of the overall softness of the sports-car market, and partly, according to Philip R. Martens, Mazda’s managing director, because it just didn’t make business sense to meet stringent U.S. pollution laws. “We could have made it comply with emissions, but the costs of the catalytic converter and some of the other things were just too high,” says Martens, whose daily driver around Hiroshima is the latest twin-turbo 280-bhp RX-7 variant, still sold in Japan.
Enter the new Renesis rotary, a 2-rotor Wankel capable of similar output without turbos and having, more importantly, a clean bill of U.S. emissions health “into the foreseeable future, which to me is 10 years plus,” says Martens. Showcased in the new RX-8 (see “Sports Car Tsunami,” March 2001), the Renesis is the anchor point for a whole family of engines. “The essence of the program was not to develop an engine tailored for one car; I believe there’s enough bandwidth in the sports segment for more signature products along that range,” Martens said.
Key to the design is moving the exhaust port from the periphery of the rotor’s trochoid-shaped housing (picture a cocoon, or a fat peanut shell) to the side plates, where the intake ports also reside. Not only does this design eliminate port overlap, the two side exhaust ports per chamber offer nearly twice the area of the single peripheral port for greater power.
And where unburned hydrocarbons used to have an easy escape path out the exhaust, the Renesis’ side-port design corrals them against the trailing apex seal, below the port; they’re then carried through to the next combustion cycle, lowering emissions. A double-walled exhaust manifold plus the absence of turbochargers also means less heat loss before the 2-stage converter, critical to emissions at start-up when an engine is at its dirtiest. “Our research center has spent a tremendous amount of time working on the catalytic treatment,” says Martens, “to make sure we don’t choke the exhaust, which is key to the free-revving performance we want.”
Free-revving indeed; the rotors are a full 14 percent lighter than their earlier counterparts, enabling a 10,000-rpm redline that takes bragging rights away from the Honda S2000’s 9000-rpm zenith. (It should be noted that each revolution of the rotor translates to three revolutions of the eccentric shaft, the rotary’s equivalent of a crankshaft.) There are numerous other smaller changes—an elaborately baffled oil sump whose ultra-slender 1.6-in. depth allows the engine to be set lower in the car; injectors that more finely atomize the fuel; a triple-path induction system that takes full advantage of the resonance “supercharging” effect; and an advanced engine-management system that’s said not to use oxygen sensors at all.
If a ***** exists in the Renesis’ armor, it’s in torque production—in current tune, it generates 153 lb.-ft. at 7500 rpm. Curiously, those numbers are identical to the S2000’s, and that car has been criticized for lack of low-end grunt. But Martens stresses that it’s how the torque is distributed—and how it’s matched to the car’s yet-to-be finalized gearing—that will ultimately impact the RX-8’s fun-to-drive quotient.
“We want to have the feeling of, ‘Oh my god, I didn’t know this would do that in this range,’ ” he said. “Flat torque curves are great, but what we really want is a lively car. It has to have a unique identity when you get in and drive it.” We anxiously await the production version.
Technology Update: Renesis Rotary
Mazda reinvents the Wankel—again
By Douglas Kott
“The piston engine goes boing, boing, boing, boing, boing—but the Mazda goes hmmmmm.” Remember Mazda’s admittedly cornball 1970s’ TV ad? Complete with a kid on a pogo stick embodying the evils of pure reciprocating movement, the spot touted the smoothness of this novel powerplant that melds the Otto cycle’s four events of intake, compression, power and exhaust with a rotating motion. Like the Porsche 911’s air-cooled flat-6 or Saab’s quirky 2-strokes, the Wankel will be forever linked with Mazda, as it has twirled beneath the hoods of RX-2s, RX-3s, three generations of RX-7s—and even, for the Japanese market, a 26-passenger bus called the Parkway Rotary—for more than three decades.
Yet the concept was dreamed up—quite literally—in the summer of 1919 by a 17-year-old German boy, Felix Wankel. In his dream, Wankel drove a car of his own construction to a concert, where he even remembered boasting to his friends, “My car has a new type of engine: a half-turbine, half-reciprocating engine. I invented it!” Wankel succeeded in turning his vision into hard prototypes, at first with the German government and later with NSU, which first built a Wankel-type supercharger that enabled its 50-cc motorcycle to set a world speed record of 122.7 mph in the mid-1950s. NSU ultimately focused on four wheels, building a single-rotor 2-seat roadster called the Wankel Spider in 1963, followed by the homely Ro 80 2-rotor sedan of 1967.
Both GM and Mercedes-Benz took long, hard looks at the rotary’s viability. But it was Mazda, largely through the engineering brilliance of Kenichi Yamamoto, that refined the design and made the rotary engine a reliable, mass-produced reality. Since the Japanese introduction of the Mazda Cosmo Sport roadster in 1967, Mazda worldwide has sold more than 1.8 million rotary-powered cars, trucks…and the occasional bus.
Sadly, the last U.S.-market RX-7 blinked its taillights goodbye in 1996. Why did that sports car, practically deified by the automotive press including Road & Track, go away? Partly because of the overall softness of the sports-car market, and partly, according to Philip R. Martens, Mazda’s managing director, because it just didn’t make business sense to meet stringent U.S. pollution laws. “We could have made it comply with emissions, but the costs of the catalytic converter and some of the other things were just too high,” says Martens, whose daily driver around Hiroshima is the latest twin-turbo 280-bhp RX-7 variant, still sold in Japan.
Enter the new Renesis rotary, a 2-rotor Wankel capable of similar output without turbos and having, more importantly, a clean bill of U.S. emissions health “into the foreseeable future, which to me is 10 years plus,” says Martens. Showcased in the new RX-8 (see “Sports Car Tsunami,” March 2001), the Renesis is the anchor point for a whole family of engines. “The essence of the program was not to develop an engine tailored for one car; I believe there’s enough bandwidth in the sports segment for more signature products along that range,” Martens said.
Key to the design is moving the exhaust port from the periphery of the rotor’s trochoid-shaped housing (picture a cocoon, or a fat peanut shell) to the side plates, where the intake ports also reside. Not only does this design eliminate port overlap, the two side exhaust ports per chamber offer nearly twice the area of the single peripheral port for greater power.
And where unburned hydrocarbons used to have an easy escape path out the exhaust, the Renesis’ side-port design corrals them against the trailing apex seal, below the port; they’re then carried through to the next combustion cycle, lowering emissions. A double-walled exhaust manifold plus the absence of turbochargers also means less heat loss before the 2-stage converter, critical to emissions at start-up when an engine is at its dirtiest. “Our research center has spent a tremendous amount of time working on the catalytic treatment,” says Martens, “to make sure we don’t choke the exhaust, which is key to the free-revving performance we want.”
Free-revving indeed; the rotors are a full 14 percent lighter than their earlier counterparts, enabling a 10,000-rpm redline that takes bragging rights away from the Honda S2000’s 9000-rpm zenith. (It should be noted that each revolution of the rotor translates to three revolutions of the eccentric shaft, the rotary’s equivalent of a crankshaft.) There are numerous other smaller changes—an elaborately baffled oil sump whose ultra-slender 1.6-in. depth allows the engine to be set lower in the car; injectors that more finely atomize the fuel; a triple-path induction system that takes full advantage of the resonance “supercharging” effect; and an advanced engine-management system that’s said not to use oxygen sensors at all.
If a ***** exists in the Renesis’ armor, it’s in torque production—in current tune, it generates 153 lb.-ft. at 7500 rpm. Curiously, those numbers are identical to the S2000’s, and that car has been criticized for lack of low-end grunt. But Martens stresses that it’s how the torque is distributed—and how it’s matched to the car’s yet-to-be finalized gearing—that will ultimately impact the RX-8’s fun-to-drive quotient.
“We want to have the feeling of, ‘Oh my god, I didn’t know this would do that in this range,’ ” he said. “Flat torque curves are great, but what we really want is a lively car. It has to have a unique identity when you get in and drive it.” We anxiously await the production version.
Heres a R&T article you may find interesting.....
Technology Update: Renesis Rotary
Mazda reinvents the Wankel—again
By Douglas Kott
“The piston engine goes boing, boing, boing, boing, boing—but the Mazda goes hmmmmm.” Remember Mazda’s admittedly cornball 1970s’ TV ad? Complete with a kid on a pogo stick embodying the evils of pure reciprocating movement, the spot touted the smoothness of this novel powerplant that melds the Otto cycle’s four events of intake, compression, power and exhaust with a rotating motion. Like the Porsche 911’s air-cooled flat-6 or Saab’s quirky 2-strokes, the Wankel will be forever linked with Mazda, as it has twirled beneath the hoods of RX-2s, RX-3s, three generations of RX-7s—and even, for the Japanese market, a 26-passenger bus called the Parkway Rotary—for more than three decades.
Yet the concept was dreamed up—quite literally—in the summer of 1919 by a 17-year-old German boy, Felix Wankel. In his dream, Wankel drove a car of his own construction to a concert, where he even remembered boasting to his friends, “My car has a new type of engine: a half-turbine, half-reciprocating engine. I invented it!” Wankel succeeded in turning his vision into hard prototypes, at first with the German government and later with NSU, which first built a Wankel-type supercharger that enabled its 50-cc motorcycle to set a world speed record of 122.7 mph in the mid-1950s. NSU ultimately focused on four wheels, building a single-rotor 2-seat roadster called the Wankel Spider in 1963, followed by the homely Ro 80 2-rotor sedan of 1967.
Both GM and Mercedes-Benz took long, hard looks at the rotary’s viability. But it was Mazda, largely through the engineering brilliance of Kenichi Yamamoto, that refined the design and made the rotary engine a reliable, mass-produced reality. Since the Japanese introduction of the Mazda Cosmo Sport roadster in 1967, Mazda worldwide has sold more than 1.8 million rotary-powered cars, trucks…and the occasional bus.
Sadly, the last U.S.-market RX-7 blinked its taillights goodbye in 1996. Why did that sports car, practically deified by the automotive press including Road & Track, go away? Partly because of the overall softness of the sports-car market, and partly, according to Philip R. Martens, Mazda’s managing director, because it just didn’t make business sense to meet stringent U.S. pollution laws. “We could have made it comply with emissions, but the costs of the catalytic converter and some of the other things were just too high,” says Martens, whose daily driver around Hiroshima is the latest twin-turbo 280-bhp RX-7 variant, still sold in Japan.
Enter the new Renesis rotary, a 2-rotor Wankel capable of similar output without turbos and having, more importantly, a clean bill of U.S. emissions health “into the foreseeable future, which to me is 10 years plus,” says Martens. Showcased in the new RX-8 (see “Sports Car Tsunami,” March 2001), the Renesis is the anchor point for a whole family of engines. “The essence of the program was not to develop an engine tailored for one car; I believe there’s enough bandwidth in the sports segment for more signature products along that range,” Martens said.
Key to the design is moving the exhaust port from the periphery of the rotor’s trochoid-shaped housing (picture a cocoon, or a fat peanut shell) to the side plates, where the intake ports also reside. Not only does this design eliminate port overlap, the two side exhaust ports per chamber offer nearly twice the area of the single peripheral port for greater power.
And where unburned hydrocarbons used to have an easy escape path out the exhaust, the Renesis’ side-port design corrals them against the trailing apex seal, below the port; they’re then carried through to the next combustion cycle, lowering emissions. A double-walled exhaust manifold plus the absence of turbochargers also means less heat loss before the 2-stage converter, critical to emissions at start-up when an engine is at its dirtiest. “Our research center has spent a tremendous amount of time working on the catalytic treatment,” says Martens, “to make sure we don’t choke the exhaust, which is key to the free-revving performance we want.”
Free-revving indeed; the rotors are a full 14 percent lighter than their earlier counterparts, enabling a 10,000-rpm redline that takes bragging rights away from the Honda S2000’s 9000-rpm zenith. (It should be noted that each revolution of the rotor translates to three revolutions of the eccentric shaft, the rotary’s equivalent of a crankshaft.) There are numerous other smaller changes—an elaborately baffled oil sump whose ultra-slender 1.6-in. depth allows the engine to be set lower in the car; injectors that more finely atomize the fuel; a triple-path induction system that takes full advantage of the resonance “supercharging” effect; and an advanced engine-management system that’s said not to use oxygen sensors at all.
If a ***** exists in the Renesis’ armor, it’s in torque production—in current tune, it generates 153 lb.-ft. at 7500 rpm. Curiously, those numbers are identical to the S2000’s, and that car has been criticized for lack of low-end grunt. But Martens stresses that it’s how the torque is distributed—and how it’s matched to the car’s yet-to-be finalized gearing—that will ultimately impact the RX-8’s fun-to-drive quotient.
“We want to have the feeling of, ‘Oh my god, I didn’t know this would do that in this range,’ ” he said. “Flat torque curves are great, but what we really want is a lively car. It has to have a unique identity when you get in and drive it.” We anxiously await the production version.
Technology Update: Renesis Rotary
Mazda reinvents the Wankel—again
By Douglas Kott
“The piston engine goes boing, boing, boing, boing, boing—but the Mazda goes hmmmmm.” Remember Mazda’s admittedly cornball 1970s’ TV ad? Complete with a kid on a pogo stick embodying the evils of pure reciprocating movement, the spot touted the smoothness of this novel powerplant that melds the Otto cycle’s four events of intake, compression, power and exhaust with a rotating motion. Like the Porsche 911’s air-cooled flat-6 or Saab’s quirky 2-strokes, the Wankel will be forever linked with Mazda, as it has twirled beneath the hoods of RX-2s, RX-3s, three generations of RX-7s—and even, for the Japanese market, a 26-passenger bus called the Parkway Rotary—for more than three decades.
Yet the concept was dreamed up—quite literally—in the summer of 1919 by a 17-year-old German boy, Felix Wankel. In his dream, Wankel drove a car of his own construction to a concert, where he even remembered boasting to his friends, “My car has a new type of engine: a half-turbine, half-reciprocating engine. I invented it!” Wankel succeeded in turning his vision into hard prototypes, at first with the German government and later with NSU, which first built a Wankel-type supercharger that enabled its 50-cc motorcycle to set a world speed record of 122.7 mph in the mid-1950s. NSU ultimately focused on four wheels, building a single-rotor 2-seat roadster called the Wankel Spider in 1963, followed by the homely Ro 80 2-rotor sedan of 1967.
Both GM and Mercedes-Benz took long, hard looks at the rotary’s viability. But it was Mazda, largely through the engineering brilliance of Kenichi Yamamoto, that refined the design and made the rotary engine a reliable, mass-produced reality. Since the Japanese introduction of the Mazda Cosmo Sport roadster in 1967, Mazda worldwide has sold more than 1.8 million rotary-powered cars, trucks…and the occasional bus.
Sadly, the last U.S.-market RX-7 blinked its taillights goodbye in 1996. Why did that sports car, practically deified by the automotive press including Road & Track, go away? Partly because of the overall softness of the sports-car market, and partly, according to Philip R. Martens, Mazda’s managing director, because it just didn’t make business sense to meet stringent U.S. pollution laws. “We could have made it comply with emissions, but the costs of the catalytic converter and some of the other things were just too high,” says Martens, whose daily driver around Hiroshima is the latest twin-turbo 280-bhp RX-7 variant, still sold in Japan.
Enter the new Renesis rotary, a 2-rotor Wankel capable of similar output without turbos and having, more importantly, a clean bill of U.S. emissions health “into the foreseeable future, which to me is 10 years plus,” says Martens. Showcased in the new RX-8 (see “Sports Car Tsunami,” March 2001), the Renesis is the anchor point for a whole family of engines. “The essence of the program was not to develop an engine tailored for one car; I believe there’s enough bandwidth in the sports segment for more signature products along that range,” Martens said.
Key to the design is moving the exhaust port from the periphery of the rotor’s trochoid-shaped housing (picture a cocoon, or a fat peanut shell) to the side plates, where the intake ports also reside. Not only does this design eliminate port overlap, the two side exhaust ports per chamber offer nearly twice the area of the single peripheral port for greater power.
And where unburned hydrocarbons used to have an easy escape path out the exhaust, the Renesis’ side-port design corrals them against the trailing apex seal, below the port; they’re then carried through to the next combustion cycle, lowering emissions. A double-walled exhaust manifold plus the absence of turbochargers also means less heat loss before the 2-stage converter, critical to emissions at start-up when an engine is at its dirtiest. “Our research center has spent a tremendous amount of time working on the catalytic treatment,” says Martens, “to make sure we don’t choke the exhaust, which is key to the free-revving performance we want.”
Free-revving indeed; the rotors are a full 14 percent lighter than their earlier counterparts, enabling a 10,000-rpm redline that takes bragging rights away from the Honda S2000’s 9000-rpm zenith. (It should be noted that each revolution of the rotor translates to three revolutions of the eccentric shaft, the rotary’s equivalent of a crankshaft.) There are numerous other smaller changes—an elaborately baffled oil sump whose ultra-slender 1.6-in. depth allows the engine to be set lower in the car; injectors that more finely atomize the fuel; a triple-path induction system that takes full advantage of the resonance “supercharging” effect; and an advanced engine-management system that’s said not to use oxygen sensors at all.
If a ***** exists in the Renesis’ armor, it’s in torque production—in current tune, it generates 153 lb.-ft. at 7500 rpm. Curiously, those numbers are identical to the S2000’s, and that car has been criticized for lack of low-end grunt. But Martens stresses that it’s how the torque is distributed—and how it’s matched to the car’s yet-to-be finalized gearing—that will ultimately impact the RX-8’s fun-to-drive quotient.
“We want to have the feeling of, ‘Oh my god, I didn’t know this would do that in this range,’ ” he said. “Flat torque curves are great, but what we really want is a lively car. It has to have a unique identity when you get in and drive it.” We anxiously await the production version.
So they purposely wanted carbon to be carried throughout the engine to reduce emissions?
Isn't this the reason for the excessive 'carbon lock' issue with our engines?
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Keep in mind that they had to meet emissions requirements to bring the car to the American market at all. I'm not defending their decision, but they didn't really have the choice to make the car more reliable but with more emissions.
At least they gave us the 8yr/100k warranty. So, they are eating a lot of the downside of this.
At least they gave us the 8yr/100k warranty. So, they are eating a lot of the downside of this.
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From: Hunterdon County
"The shape of the side seals is interesting as well. It is a wedge shape. This is to help remove any carbon from building up in the groove which would cause it to stick. Carbon is also the reason for the interesting shape of the Renesis exhaust ports as well as the overly large seal clearances in the Renesis over the 13B. And some of you thought carbon was related to synthetic oils! Shame on you! That was actually the reason why we haven't seen a side ported rotary until the Renesis. Back in the '70's Mazda did try the side exhaust port and back then they also found it to be superior. The problem was the carbon would cause seals to stick and break. You can't market that. They met the standards of the time with the peripheral exhaust port so that's what they stuck with."
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Joined: Apr 2005
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Likes: 340
From: Australia
Keep in mind that they had to meet emissions requirements to bring the car to the American market at all. I'm not defending their decision, but they didn't really have the choice to make the car more reliable but with more emissions.
At least they gave us the 8yr/100k warranty. So, they are eating a lot of the downside of this.
At least they gave us the 8yr/100k warranty. So, they are eating a lot of the downside of this.
This guy told me if the new series II RENESIS with the extra lube nozzle for each rotor chamber and the other mods they have done does not halt the number of failed engines they doubt we will see a future at all until alternative energy sources are mainstream.
BTW, the number of engines replaced has topped 50,000 according to him. (about 25%)
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From: Hunterdon County
Yeah, too much eating I have heard from a close Mazda source, Mazda are not happy with the cost of failed engines particularly in the US where the previous reman guys stuffed up so many times with owners have engines changed 3 and 4 times.
This guy told me if the new series II RENESIS with the extra lube nozzle for each rotor chamber and the other mods they have done does not halt the number of failed engines they doubt we will see a future at all until alternative energy sources are mainstream.
BTW, the number of engines replaced has topped 50,000 according to him. (about 25%)
This guy told me if the new series II RENESIS with the extra lube nozzle for each rotor chamber and the other mods they have done does not halt the number of failed engines they doubt we will see a future at all until alternative energy sources are mainstream.
BTW, the number of engines replaced has topped 50,000 according to him. (about 25%)
BTW, I'd feel a lot better if those Series 2 Renesis engines had Sohn adapters with a clean Idemitsu supply and/or a good premix regime, maybe some FP+. Wonder what your source thinks of these ideas that are so popular among enthusiasts?
Yeah, too much eating I have heard from a close Mazda source, Mazda are not happy with the cost of failed engines particularly in the US where the previous reman guys stuffed up so many times with owners have engines changed 3 and 4 times.
This guy told me if the new series II RENESIS with the extra lube nozzle for each rotor chamber and the other mods they have done does not halt the number of failed engines they doubt we will see a future at all until alternative energy sources are mainstream.
BTW, the number of engines replaced has topped 50,000 according to him. (about 25%)
This guy told me if the new series II RENESIS with the extra lube nozzle for each rotor chamber and the other mods they have done does not halt the number of failed engines they doubt we will see a future at all until alternative energy sources are mainstream.
BTW, the number of engines replaced has topped 50,000 according to him. (about 25%)
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From: Hunterdon County
Of course, that's why Al commented on the new perspective that time brings, which is also why I added rg's perspective on the original side exhaust port rotaries from the early 70s. Old farts like (Chris and) me understand the importance of historical perspective.
I actually find some of these old threads VERY interesting. It's neat to see what people's thoughts were BEFORE the release and view and comment on them NOW that the 1st Gens run is over and the new RX8 is out.
Good find Chris
Good find Chris
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Joined: Apr 2005
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From: Australia
That is stunning! How reliable is your source's info?
BTW, I'd feel a lot better if those Series 2 Renesis engines had Sohn adapters with a clean Idemitsu supply and/or a good premix regime, maybe some FP+. Wonder what your source thinks of these ideas that are so popular among enthusiasts?
BTW, I'd feel a lot better if those Series 2 Renesis engines had Sohn adapters with a clean Idemitsu supply and/or a good premix regime, maybe some FP+. Wonder what your source thinks of these ideas that are so popular among enthusiasts?