Mazda RX8 Horsepower Controversy

Since its launch, the Mazda RX8 has been the subject of close scrutiny by enthusiasts. The high level of attention is not only due to the car’s admirable driving dynamics but, in part to the early reports of below-than-expected performance. To be more specific: wheel horsepower measured on several chassis dynamometer runs resulted in values well below the expected 17%~20% drivetrain parasitic losses. And quarter mile runs of anywhere between 0.5 and 1.5 seconds off of those produced by magazines on allegedly pre-production vehicles.

In connection with the RX8’s horsepower rating: the original marketing material from Mazda North America (MNAO) advertised the 6 speed manual transmission RX8 at 247hp @ 8,500rpm. Assuming parasitic drivetrain loses between 17%-20% –common for modern rear wheel drive vehicles, a stock RX8 should measure between 205~197 horsepower at the rear wheels (rwhp) –depending on elevation, barometric pressure, temperature and correction factors applied. Instead, a stock RX8 chassis dyno run shows results ranging anywhere from mid-high ~160 to ~185rwhp. Such readings would represent parasitic drivetrain loses in excess of 25%. To say that, it is unacceptable to experience such a high level of loss through the drivetrain of a “sports car” with a carbon fiber drive shaft –amongst other things- is an understatement.

To further consolidate doubts about the actual power output of the new Renesis, several owners were unable to reproduce mid-low 14 second quarter mile passes -as seen published by well known U.S. car magazines. Low trap speeds were another hint towards the apparent lack of power output.

Shortly after, several debates on online enthusiast forums and discussion boards turned into heated arguments as to what was causing such poor "straight line performance." Many former Miata owners remembered a previous "snafu" in Mazda's history, when the manufacturer admittedly overstated the horsepower figures of their redesigned Mazda Miata.

After a few months, MNAO came forward and explained that they had misrepresented the Renesis' power output. The revised figure was now 238hp @ 8,500rpm; however, according to MNAO, this revision did not change the previously achieved track performance results.

Speculations about the reasons behind the sudden lack of power output were many. However, there are currently two schools of thought:


The first one supports the idea that the RX-8's engine management unit (ECU), in conjunction with the many "nanny" devices -such as ABS & TCS- do not allow to obtain accurate readings from a chassis dynamometer. To simplify, when the car is run on a chassis dyno, only the driven wheels are turning. The RX-8's ECU would detect an abnormal driving situation and retard timing and apply other safety measures to preserve either the "driver" or the "engine" -or both- from damage (read: skidding situation, or a car going out of the road.)
The second one believes that MNAO was forced to re-engineer the software that runs the engine management even before the first batch of RX-8's reached U.S. shores, due to upcoming Federal emissions regulations. I have read of one in particular, which requires catalytic converter lifespan of ~100,000 miles. The enemy number one of catalytic converters on any vehicle is heat (and heat is the number one attribute of rotary engine's exhaust gases.)

MNAO offered two options to those who had pre-ordered an RX-8, or had purchased no late than September 2003:


They would buy back the vehicle, no questions asked.
They would offer FREE Scheduled Maintenance for the life of the warranty, plus a 500 dollar "gift card" to those who opted to keep the car.

I was among those who opted to keep their RX-8. After all, the driving experience had not changed since test driving the vehicle prior to purchasing it. Since August 2003 I have clocked well over 20,000 miles -as of 1/18/2005- and I have but one ounce of regret about my decision. If you'd like to read more about owners' opinions, visit this thread @ RX8Club.com

There have been a number of ECU "updates" released during the past 2 years. To the best of my knowledge, all early samples of '04 RX-8s, came from port with level "J" of engine management software. Since then, we have escalated all the way through the alphabet to "M" -which was released on a TSB campaign by Mazda North America (MSP04) in order to have ALL vehicles taken in for Service @ Authorized Dealers flashed to "M" calibration.

ON THE ROAD MAZDA RX-8; Amazing, all-round Wankel winner

THERE IS no other car quite like the Mazda RX-8. It has the singular body style to go with its singular engine, and it brings a whole new slant to the notion of a sporty GT coupe.

Its Audi arch-rival is a four-seater, but only just. The new Nissan 350Z and Chrysler Crossfire do not even attempt that feat. In the Mazda, though, we find not just a pair of habitable rear chairs but also dedicated doors through which to reach them. Mazda calls them "freestyle" doors; they are short and hinged on their rear edges, and have no pillar ahead of them against which to close.

Instead, they latch at the top and bottom of their front edges, to form the "pillars" against which the long front doors then shut. It is an inspired piece of packaging, but another piece of RX-8 is arguably even more inspired: its rotary engine.

This smooth-spinning, piston-less engine design, invented by German engineer Felix Wankel, was first used in an NSU sports car. It gained equal adulation and notoriety powering NSU's fabulous but flawed Ro80 saloon of 1967, a futuristic car whose warranty claims sunk its maker, but Mazda, which has made rotary-engined cars since 1967's Cosmo Sport 110S, rendered it reliable.

But Mazda could not solve the fuel thirst and noxious emissions, which is why the RX-7, descendant of a sports coupe line begun in the 1970s, was denied to Europe after 1997 although buyers on the Japanese home market could purchase one until last year.

Now, the RX-8's new "RENESIS" (Rotary Engine Genesis) engine has fixed the emissions and economy issues well enough to satisfy EC pollution police, and we can again enjoy an engine with less vibration than any other internal- combustion unit. Its two convex- triangular rotors sweep chambers with 1,308cc total volume, but because of the way the engine works this equates to 2,616cc of normal motor.

You can sense the difference as soon as you start it. The sound is halfway between a regular straight-six and a two-stroke engine without the pops and bangs. This Mazda comes with a choice of power outputs, the regular 192bhp matched to a five-speed gearbox (pounds 20,000) and the Hi-Power with 231bhp, xenon headlights with washers, aluminium pedals and, crucially, a six-speed gearbox. It costs an extra pounds 2,000, and is worth every penny.

I drove the 192bhp version first. It looks just like the more powerful RX-8 apart from the lack of headlamp washers, with front wheel arches so bold and a bonnet so tapered it almost seems to have the separate front wings of a pre-war sports car. And then there are the engine-rotor motifs, on the lower front air intake, the rear foglight, the holes in the headrests and on the gearlever. They are there to remind you; apparently, many American RX-7 owners did not even know their cars had rotary engines.

First, the downsides. The perforated sunvisors do not shield the sun well. The accelerator response can be snatchy, there is engine surge in traffic and occasionally the transmission clonks. Then, when you are out on a fast, open road you find the engine runs out of puff on hills so you have to downshift and rev it to oblivion.

But, on the bends, the RX-8 is total joy. The steering's response is instant and precise, a true mechanical connection to the front wheels without the initial uncertainty found in the Mazda's key rivals. The front wheels bite cleanly into the road, and you can power out of corners with that balanced, slingshot feeling only a powerful rear-wheel drive car can give. It also feels solid and well- made, so the firm suspension does not result in a turbulent ride. But should it not feel a little faster?

It should, which is why the Hi-Power is the RX-8 to have. The engine revs to crazy heights (well past 8,000rpm) and that extra gear exploits this broader rev-range. It does not matter that the engine speeds are higher because it is so smooth and musical, and the engine is never caught napping because there is always a suitable gear to keep it interested. I have not driven a more beguiling engine all year.

In every major way, this is the best of the new breed of sporty coupes. The driver of a grey-import RX-7, who followed me for miles before passing with a thumbs-up, thought so too.

Model: Mazda RX-8 Hi-Power;

Price: pounds 22,000 (on sale October);

Engine: 1,308cc rotary, two rotors, no valves, 231bhp at 8,200rpm;

Transmission: Six-speed gearbox, rear-wheel drive;

Performance: 146mph, 0-60 in 6.4sec, 24.8mpg (official average);

CO2: 284g/km.

Mazda Hits Home Run With RX-8 Styling, Price Point; - New Rotary-Powered RX-8 Is a Sports Car Like No Other -

Mazda hit the sweet spot when it debuted the all-new, rotary-powered RX-8 sports car in January at the North American International Auto Show in Detroit. With an athletically sculpted exterior and one-of-a-kind rotary engine, the Mazda RX-8 is priced from $25,180 with a 210-horsepower engine and four-speed automatic transmission. Equipped with a 250-horsepower engine, six-speed manual transmission and 18-inch wheels and tires, the RX-8 is priced from $26,680. It is propelled by the all-new 13B RENESIS rotary engine and is the latest in a three-decade-long line of Mazda rotary-powered vehicles.

Mazda continues to pioneer cutting-edge styling with the RX-8's unique freestyle four-door design, effectively demonstrating that a true sports car does not need to sacrifice space or convenience. With enough passenger room for four full-size adults and enough trunk space to fit luggage for a weekend or two full-size golf bags, soulful driving is no longer solely for the driver.

Both automatic and manual transmission cars come equipped with power windows, mirrors and door locks, cruise control and an AM/FM/CD audio system with six speakers. To make ordering easy, both the automatic and manual are offered in four trim packages: a Base Model, Sport Package, Touring Package and Grand Touring Package. Priced from $1,100 for the manual transmission Sport Package to $4,600 for the automatic Grand Touring Package, they include accoutrements like Xenon headlights, Dynamic Stability Control with traction control, a BOSE(R) audio system, heated seats and leather trimmed upholstery.

The RX-8 delivers unprecedented sports car driving pleasure with the RENESIS rotary engine offering smooth, immediate power. Double wishbone front and multi-link rear suspension, complemented by electric power-assisted steering, yields razor sharp handling.

In addition to being the most revolutionary and cutting-edge sports car, the RX-8 is also one of the safest with standard features like ABS with Electronic Brake Distribution, front- and seat-mounted airbags as well as side air curtains. Mazda also incorporated high-strength steel construction for the side paneling and a special door-latch system in the freestyle door openings to create a solid exterior shell. The RX-8 is truly a sports car like no other at a value like no other.

The Mazda RX-8 comes with a four-year roadside assistance program. With a call to a toll-free number, RX-8 owners can access roadside assistance 24 hours a day, 365 days a year throughout the United States and Canada. For all 2003 Mazda vehicles, the company will provide a free loaner car in the event a warrantable condition requires alternative transportation.

The RX-8 is covered by a comprehensive four-year/50,000-mile warranty that covers every part on the vehicle except those subject to normal wear. In addition, the RX-8 is covered by a five-year/unlimited-mileage corrosion warranty.

Mazda North American Operations is responsible for the sales and marketing, customer parts and services support of Mazda vehicles in the United States.

Headquartered in Irvine, Calif., MNAO has more than 700 dealerships nationwide.

Mazda RX-8

Mazda made its name in America in the early 1970s with a Wankel rotary engine propelling most of its cars. By 1973, they had climbed to fifth in U.S. sales with 92 percent of its 119,000 sales, rotary powered.

With its only major moving part a triangular rotor spinning in a cocoon-shaped combustion chamber through intake, compression, combustion and exhaust cycles, the rotary's appeal was a combination of compact size, smoothness, pleasing power and high-rpm zing. But it soon revealed a dark side: a &raking problem (fuel and oil consumption) combined with reliability, durability and emissions issues.

Bad word-of-mouth and the 73 fuel crisis squashed U.S. sales to 61,000 in 1974, but the company moved quickly to proliferate piston power through its line while improving the rotary for performance models, striking gold in 1979 with the RX-7 sports car, the most successful model in IMSA racing history. Rotary-powered prototypes scored U.S. and international victories including the 1991 24-Hours of LeMan. But when Mazda dropped its third-generation RX-7 in the mid-'90s, the rotary was history.

Or was it? The '03 debut of Mazda's RX-8 4-seat sportster marked the rotary's return in much-improved form after an 8-year hiatus. The 1.3L two-rotor RENESIS (Rotary-Engine Genesis) engine pumps 238 eager horses through a 6-speed manual, or 197 through a 4speed automatic. The car's shape is sinuously sexy, its front-facing rear doors and pillarless body offer easy access to a reasonable rear cabin, and its front mid-engine/RWD layout gives a low center of gravity and perfect 50/50 weight distribution for racer-like handling.

At roughly $27,000 and 18/24-mpg economy, the RX-8 still imbibes too much gas and (according to owners) oil as part of its unique character. But it's a genuine driver's delight.

MAZDA RX-8 HYDROGEN ROTARY ENGINE: A SPORTS CAR (AND ENGINE) LIKE NO OTHER

With a cat-like predatory stance, forward-thinking freestyle door system and enough room for four, not two, adults to enjoy all its benefits, the Mazda RX-8 has set itself apart from the pack. But if the recently introduced RX-8 production sports car truly is unique thanks, in large part, to its rotary engine, the RX-8 Hydrogen Rotary Engine (RE) concept, showcased this year at the North American International Auto Show (NAIAS), takes "unique" to all new levels.

Featuring a fuel system that consists of a high-pressure hydrogen tank, the Mazda RX-8 balances the needs of the driving enthusiast and the environmentalist with a blend of alternative power and the exhilarating driving experience for which Mazda is known.

As the auto industry turns its attention to hydrogen fuel as a gasoline alternative, the RX-8 Hydrogen RE offers a hydrogen-powered version of RENESIS—Mazda’s next generation rotary engine that was introduced last year in the all-new RX-8. By virtue of its smooth performance, compact size and impressive driving characteristics, RENESIS was named International Engine of the Year in June 2003.

The RENESIS Hydrogen RE allows the RX-8 concept to run on either hydrogen fuel or gasoline and capitalizes on all the advantages of the rotary to assure RX-8’s ease-of-operation and reliability.

The RENESIS Hydrogen RE incorporates an electronically controlled hydrogen injector system, with the hydrogen injected in a gaseous state. The system draws air from the side port during the intake cycle and uses dual hydrogen injectors in each of the engine’s twin rotor housings to directly inject hydrogen into the intake chambers.

Because it offers separate chambers for intake and combustion, the rotary engine is ideal for burning hydrogen without the backfiring that can occur in a traditional piston engine. The separate induction chamber also provides a safer temperature for fitting the dual hydrogen injectors with their rubber seals, which are susceptible to the high temperatures encountered in a conventional reciprocating piston engine.

Also helping to maximize the benefits of the rotary engine in hydrogen combustion mode, the RENESIS Hydrogen RE features adequate space for the installation of two injectors per intake chamber. Because hydrogen has an extremely low density, a much greater injection volume is required compared with gasoline, thus demanding the use of more than one injector. Typically, this can be difficult to achieve with a conventional reciprocating piston engine because of the structural constraints that prevent mounting injectors in the combustion chamber. However, with its twin hydrogen injectors, the RENESIS Hydrogen RE is both practical and able to deliver sufficient power.

In addition to the revolutionary hydrogen-powered RENESIS rotary engine, the Mazda RX-8 Hydrogen RE concept benefits from improved aerodynamics and optimized tires and weight-saving measures. A fast-fill tandem master cylinder reduces brake drag and friction hub carriers help cut power losses.

The vehicle also incorporates a host of other technologies for exceptional environmental compatibility. Three-layer, wet-on water-based paint on the RX-8 Hydrogen RE dramatically reduces the emission of organic solvents, saves energy by shortening the drying process and reduces carbon dioxide emissions. Moreover, the plant-based plastics used for the vehicle’s interior parts provide an attractive alternative to plastics derived from fossil fuels such as petroleum.

The Mazda RX-8 Hydrogen RE illustrates Mazda’s dedication to the future environment without abandoning true Zoom-Zoom and soul-of-a-sports-car thinking.

Mazda North American Operations is responsible for the sales and marketing, customer parts and services support of Mazda vehicles in the United States. Headquartered in Irvine, Calif., MNAO has more than 700 dealerships nationwide.

EDITOR'S NOTE: For more information on Mazda products, visit the online Mazda media center at http://www.mazdausamedia.com/.

Rotary Engine

Many different designs for rotary mechanisms have been attempted over the last 400 years, but what makes the NSU-Wankel engine, which Mazda adopted, stand out is its "rice ball-shaped" (triangular) rotor housing. Because of this design, three separate chambers are created between the rotor and the inner wall of the rotor housing. These chambers smoothly expand and contract in a constant cycle as the rotor spins. See the rotary engine in motion on the right.
The Rotary Engine of Mazda continues to evolve farther into the future. The new generation Rotary Engine "RENESIS" makes it superbly environmentally friendly with zero CO2 and almost zero NOx emissions. Mazda began commercial leasing in 2006, and currently many organizations and government bodies are enjoying the RX-8 Hydrogen RE.

RENESIS
New generation rotary engine "RENESIS" stands for "the RE(rotary engine)'s GENESIS". The RENESIS was given to the engine as exhibited in Tokyo Motor Show, 1999 of the RX-01, after which RENESIS was meticulously prepared for series production.

By capitalizing on the instrinsic benefits of the RENESIS rotary engine camely, low weight, compact size and high performance, Mazda was able to develop the RX-8, a sholly new concept, 4-door 4-seater Genuine sports car.

RENESIS is a 654cc ﾗ2 rotor engine that generates an outstanding 250 PS(184kW) maximum power at 8500rpm and 216 N.m (22.0 kg-m) maximum torque at 5500rpm.

* RENESIS also shows a vast improvement in terms of fuel-efficiency and exhaust gas emissions.

Side-Exhaust and Side-Intake Ports
A key innovation for the RENESIS is its side-exhaust and side-intake port configuration. Previous RE designs located the exhaust ports in the rotor housing (peripheral port), whereas the latest version has its exhaust ports in the rotor housing, where the intake ports are also located.

The chief advantage of this side-exhaust / side-intake port layout is that it permits elimination of intake/exhaust port timing overlap, elimination the retention and carry-over of exhaust gas and encouraging more stable combustion. In addition, where the previous engine had one peripheral exhaust port per rotor chamber, RENESIS has two side ports, approximately doubling the port area. The new exhaust arrangement reduces exhaust gas flow-resistance, and while assuring ample exhaust port area, allows delay of the exhaust port opening for a longer expansion cycle, to raise thermal efficiency, power output and fuel economy.

Another major advantage of the side exhaust port is that it allows engineers more freedom to optimize port profiles. With RENESIS, both the 6-port engine and the 4-port engine have intake port cross-sectional area almost 30% greater than the previous engine.

from : http://www.mazda.com/