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October 18, 2000
 

Mazda Unveils Genuine Sports Car, Limited Edition RX-7 Type RZ
- Also enhances all existing RX-7 models for better handling and safety -
 

Mazda Motor Corporation announces the release of the RX-7 Type RZ, a performance-enhanced limited edition version of the RX-7, Mazda's rotary engine-powered sports car, as well as enhancements to the other models in the RX-7 lineup. The new RX-7 models, including the limited edition Type RZ, go on sale today at Mazda Anfini dealerships throughout Japan.
The limited edition RX-7 Type RZ is equipped with red custom full-bucket seats manufactured by Recaro, a custom suspension system manufactured by Bilstein, and custom aluminum wheels manufactured by BBS. These and other enhancements reduce the overall weight of the Type RZ by approximately 10kg, improving handling and performance. The Type RZ has a custom body color-snow white pearl mica. Only 175 units of this limited edition model will be sold.

The improvements to the new RX-7 lineup, in general, include modifications to the brake and suspension systems to enhance driving performance and handling stability. The interior features an instrument panel with white meters, metal plated frame rings, and red illumination for a more sporty look. The reinforced side impact bars and ABS equipped with an EBD (electrically-controlled braking distribution) system for all four wheels enhance safety.

The new RX-7 expresses Mazda's stylish, insightful and spirited brand personality. Its distinctiveness is the result of a design process emphasizing three key ideas: distinctive design, exceptional functionality, and responsive handling and performance. By exploiting the strengths of the lightweight, compact, and high-output rotary engine, RX-7 achieves an exceptional level of "responsive handling and performance." The RX-7 is the sports car that best symbolizes Mazda.

The monthly sales target is 300 units.

Primary features of the limited edition RX-7 Type RZ
  The limited edition Type RZ is based on the top-performance version of the RX-7, the Type RS, and is equipped with a number of sporty custom accessories. It is approximately 10 kg lighter than the Type RS, resulting in a power-weight ratio of 6.17 kg/kW (4.54 kg/PS). Features include the following:
  - Red custom full-bucket seats manufactured by Recaro
  - Custom "gun metallic" colored aluminum wheels manufactured by BBS
  - Custom dampers manufactured by Bilstein
  - Custom red stitched steering wheel manufactured by Nardi
  - Custom red stitched leather shift knob, stick shift boot, and parking brake lever boot
  - Driver's side kneepad
  - Passenger side aluminum footrest board
  - Rear storage box
  - Custom body color: snow white pearl mica
 

Main Product Enhancements
  Improved Braking Performance
    - The ABS control unit for all four wheels has been upgraded from the conventional 8 to 16 bits and equipped with an EBD (electrically controlled braking distribution) system. This results in shorter stopping distances when the brakes are applied suddenly and enhanced vehicle stability.
  Enhanced Ride and Maneuverability
    - The damping force of the suspension dampers has been changed (Type RB and Type RS) and a check value has been added to the power steering system for improved handling.
  Improved Safety
    - The conventional side impact bars have been reinforced with the addition of lower side impact bars positioned in the bottom portion of the doors. Also, manual transmission models have been equipped with a clutch interlock mechanism that prevents the engine from starting unless the clutch is depressed.
  Sportier Interior
    - The gauges on the instrument panel feature white text and metal plated frame rings. In addition, the gauges, climate control system, and audio system panel have red illumination for a more sporty look.
    - The center portion of the seats is covered with a knit rubber fabric for a snugger fit and a sporty feel. (Type RB S-package, Type RB automatic transmission model, Type RS)
  New Concept in Audio Systems
    - With Mazda's new concept in audio systems, a variety of module type audio kits are available, making it simple to add additional functions, such as a CD or MD player, or replace an existing function with a new one. The system is exclusive to Mazda and is designed to be expandable, so it will be ready for the next generation in media when it arrives.
  New Body Color Options
    - The following body colors are available: innocent blue mica, vintage red, pure white (new), brilliant black, sunlight silver metallic (new).
 
 

The New RS RX7 has 280 hp. low down torque has been sacrificed for high end power. There is much less turbo lag and the writer thinks the loss of low down torque isn't a problem.

If you keep the revs over 6000 the engine is very responsive and easy to control. Only the RS model has 280 hp. The other models retain 265 hp for manual and 255 for automatics. The rear is a bit too light when going through long fast corners or down hill corners. This cornering problem is solved by adjusting the new adjustable rear wing up two notches, giving more down force in the rear.

Wheels are still only 16" on the type R. the model tested. Only the type RS has 17" wheels. The writer thinks the 16" wheel should be discontinued and all models should come out with 17" wheels. The 16" wheels are two small and give too much oversteer. The type R is not good because the bilstiens are a bad combination and let the car down. It needs better shocks and 17" wheels.

The RX7 is very unique because nowadays there are many kinds of traction control and vsc and the RX7 is the only real sports car that doesn't use any electronic device. The Mazda rotary engine is still the only unique engine in the sports car market. This was a big advantage years ago but now other engines have caught up and the rotary's light weight and power advantage is getting reduced. The new rear wing was made because the RX7 is aerodynamically critical due to its light weight. the wing is adjustable to create down force and also gives a spoiling effect to reduce drag. There are 4 positions 1, 5, 10 and 14.5 degrees.
c/l value 1deg =0. 14.5 deg = -0.075

Rev counter is changed to the centre of the metre panel. "0" position is now at 6 o'clock.
Left side has a boost gauge that replaces the oil pressure gauge. Other refinements are invisible. Air flow through the engine compartment has been changed a lot to try and reduce the under hood temperatures which have been thought to create premature turbo failure. Radiator front duct entrance is 2.5 times bigger than before. Oil cooler ducting is 1.8 times bigger and ntercooler duct is 1.8 times bigger which all together allows more cooling for power upgrades. Turbo boost is up from 0.62 to 0.74 bar by using a new exhaust with less back pressure and higher flow turbos. Two kg's were removed from the front over hang by changing the radiator duct and electric fan, this has improved handling. Power to weight ratio is now 4.57 kg/hp.
Suspension has special tuning compared to before to increase road holding on winding roads.
 
 

The New 1999 FD3S has been out for a few months. I guess some of you have been wondering what's been changed (improved?). Before we look at the '99 we should get up to date with the changes made way back in ‘95~96.
The FD was basically refined, the engineers went over the car and made a few little tweaks. The doors lost their tinny clunk, when shut, in favour of a more solid thud (?). The computer processor was up-graded so that only Mr. Amamiya could do a boost up-grade and charge you double (a nice little kick back for someone at Mazda HQ in there somewhere). The rear tail lights had the fiat 124 round look added (kind of retro R100). Bigger 17" wheels for the RS-R and bigger brake disks (1"). A knee pad attached to the door and an elbow pad replacing the ashtray.
Note; There was one change before ’95. Back in 1994 the Type R was given a smaller rear antisway bar to assist off the line acceleration. The ’94 and latter Type R’s are called R2’s in Japan. For some reason the old R1’s are worth more than R2’s. I guess they changed some other things on the R model and I think the old R1 is lighter.

1999. (called, surprisingly, "NEW RX7", in Japan)
The first thing you notice is the new front and old Mazdaspeed style rear wing (and the ugly new badges).

More Power, same weight and a new colour. "Innocent Blue Mica" the next step after "Chaste White".
Leather seats are gone but we have more power, 280 PS (PS is German for "horse" "power". The Japanese adopted this some 60 years ago. For some reason the Japanese favoured German to English at that time), the Japanese car manufacturers standard self imposed limit.
This limit is really holding the Japanese back from total performance car world domination. No point building an F50 killer with 280 hp. The limit is not extended to cars imported into Japan.

The new power is achieved with a little more boost from the new turbos.
Previous standard boost was 9.08 psi (0.62 bar) now we have 10.82 psi (.746 bar).
The turbos now have an abradeable seal. The clearance between the compressor wheel and housing is zero. The compressor wheel rubs against the snail all the time. The compressor wheel diameters have been reduced from 51mm to 50mm so they will spool up quicker (less lag).
.

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The oil cooler ducts are 1.75 times bigger.
------

The intercooler duct is 1.8 times bigger. The air cleaner now has its own scoop and no longer shares leftovers from the intercooler. The brake ducts have also been increased.

Big front lip.
On the old FD a front lip air dam was fitted to the Type R and available on other models as an option.
Due to the huge openings in the front of the New FD, the volume of air entering at speed could not pass through the radiator fast enough and was coming back out again. This excess air was then flowing under the car, reducing the negative pressure and unsticking the car from the road. To combat this problem a much larger lip was added to the bottom of the front spoiler and extended to carry any excess air around to the sides of the car.
The lip also extends further forward and collects air from the in front of the car, further reducing the pressure under the car, increasing down force.

Tacho is turned a little so 6000 rpm is at 12oclock. "Nardi" steering wheel.
They have removed the little side lights in front of the front wheels.
The "Y" pipe from the turbos is now aluminium like the old 1992 13b rew Cosmo.
All new plastic pipes for the inter cooler and air box.

Optional extras.

Rear Sun Visor.

Aluminium foot pedals and foot rest. Keyless entry. Pioneer AM/FM, cassette, CD player.
-

 
 

From "Fast Fours and Rotaries. Feb/Mar '99.

Series 8
RX-7

The article appears in the September 1999 edition of SAE
Automotive Engineering International.

Mazda's rotary engine production is at most a few hundred units a month, a fraction of what it used to be in the heyday of the Hiroshima-based company's ambitious "rotarization" movement.  The rotary engine is alive in Japan, kicking harder than ever in the face-lifted and improved RX-7 sports car.

The type 13B-REW twin-rotor engine inherits the 13B design, along with the epitrochoidal dimensions and geometry, and single combustion chamber volume of 0.65 L (40 cu. in.) (x two rotors = 1.3 L, thus the "13") from the predecessor whose roots trace back to 1974.  In fact, the original type 13B shares two of the three key internal dimensions with the types 10A (1967) and 12A (1969).  These are the "E" which is eccentricity, the amount of offset between the eccentric shaft (equivalent to the crankshaft) centerline
and the rotor centerline;  and R, which is generating radius, the distance between the rotor centerline and the rotor's apex (in the Wankel rotary, each rotor has three apices).  In the three engines, these are E = 15 mm (0.6 in.) and R = 104 mm (4.1 in.).  The earliest production engine, the type 10A, obtained a single chamber volume of 0.5 L (30 cu. in.) with a 60 mm (2.4 in.) wide trochoid chamber (B in the rotary equation). The 12A, which powered the first-generation RX-7, had the chamber width increased to
70 mm (2.7 in.) for a single chamber capacity of 0.57 L (35 cu. in.). The 13B has an 80 mm width (3.2 in.) width, obtaining 0.67 L (41 cu. in.). Why the "B" designation?

There had been an odd engine, circa 1969, a twin-rotor unit with a single chamber volume of 0.65 L (40 cu. in.) with unique epitrochoidal geometry and inner dimensions:  E = 17.5 mm (0.7 in.);  R = 119 mm (4.7 in.);  and B = 60 mm (2.4 in.).  This engine was designed for a front-wheel-drive, specialty coupe, the R130 Luce Rotary, which required a shorter powerplant. The engine was given the 13A designation, as its total displacement was 1.31 L (80 cu. in.), so the later and wider-chamber, 1.31 L (79.8 cu. in.) unit had to do with the B designation.

Nobuhiro Yamamoto, responsible for the rotary engine and vehicle development, confides that there are still some minor components for the latest rotary that can be found in the corporate parts bins with the prefix 0813, which was the design code of the very first production engine 10A, circa 1967!  Mazda's rotary is indeed a small engine family.

The 13B-REW in the third-generation RX-7, launched in late 1991, was a completely redesigned unit, with numerous internal and external modifications and improvements.  The REW suffix indicates that it is a rotary engine supercharged by twin, sequential turbochargers. It was the world's first such turbo installation.  The engine produced 190 kW (255 bhp) at 6500 rpm and 294 Nm (217 lb. ft.) of torque at 5000 rpm.  Two years later, power output was increased to 198 kW (265 bhp).

By unwritten decree and industrial agreement, no Japanese manufacturer offers passenger car models with engine output greater than 209 kW (280 bhp).  Imported marques are not a party to this domestic consensus, so for them the sky's the limit.  Some members of the industry limit output of their larger displacement or more powerful powerplants.  Others try to attain the limit by tweaking up their engines.  Honda, for example, has made the mark, adding 0.19 L to the Acura NSX's exotic quad cam V6.

Now Mazda has joined the 280-bhp club.  The latest 13B-REW produces 209 kW (280 bhp) at 6500 rpm, an increase of 11 to 13 kW (15 to 18 bhp) obtained above 5000 rpm.  Torque output is also improved by 20 Nm (15 lb. ft.) in the critical mid-speed range above 2500 rpm, peaking at 314 Nm (231 lb. ft.) at 5000 rpm.  New turbochargers, improved apex seal lubrication, freer exhaust, enhanced cooling, and more elaborate engine management are cited as bringing these benefits, while the engine's internals are inherited from the previous version.

The turbocharger, two of which are used in the sequential setup, is a new Hitachi instrument with an abradable compressor sealing and an "ultra-high-flow" turbine design.  The abradable compressor housing sealing has been in U.S. markets, Toyota being the first to use it in the MR-2 sports car, some years ago.  It was one of the more promising items in the menu the Mazda's rotary engine designers had prepared a few years ago to get more power out of the 13B-REW, but, according to Yamamoto, the company was
in a dire financial state, and the design team could not dare ask for the expensive turbocharger.  The Toyota unit had plastic layer hot-sprayed onto the housing's surface, a methodology hardly suitable for large scale production, therefore costly.

Hitachi has since come up with a new built-up construction of the compressor housing.  A formed plastic inner sealing element is bolted onto the main housing, and then machined.  The turbocharger is assembled, and run up to 100,000 rpm, abrading the inner surface of the plastic seal, obtaining the closest clearance between the compressor and housing.  The new abradable turbocharger has an 80%-plus efficiency, whereas a typical instrument's efficiency is about 75%, according to a Mazda designer.  This brings down
the compressed air's temperature by 10 C, or about 10%, at the exit of the compressor.  Air temperature is still in the region of 110 C (230 F), which is further cooled down by the air-to-air intercooler in the RX-7
installation.

The latest trend in high-performance turbo technology is a "diagonal flow" turbine.  Mazda asked Hitachi to come up with several candidates of this design, hoping it would boost the engine's output.  They did not quite match the rotating piston engine's unique characteristics.  Back to the tube, as it were, to research basic flow dynamics.  The fruit of the toil is the "ultra-high-flow" turbine, with its blade length extended and its shapeless acutely curved, enlarging gas passage and reducing flow resistance.  Turbo response in the low speed zone has been greatly improved.  The turbocharger adopts a smaller diameter turbine, 50 mm (1.9 in.) now versus the previous unit's 51 mm (2.0 in.), again reducing inertia mass.  The new
"ultra-high-flow" turbine realizes about a 10% gain in efficiency, according to Mazda's turbo engineer.  The twin ultra-high-flow  turbochargers supply a maximum boost of 74.7 kPa (10.8 psi) at 6500 rpm to the previous high-flow instruments' 62.7 kPa (9.1 psi) at the same rpm.

The rotary's reliability under the severest conditions was well proven in Mazda's competition activities in the late 80's and early 90's, including an outright win in the Le Mans 24-hour race for sports racing cars in 1991.  A road car is subjected to a different kind of stress, said a Mazda designer responsible for the engine's innards, especially when the 13B-REW's output is increased to 209 kW (280 bhp).  Possible problem areas are higher combustion temperature and pressure.  The former could be dealt with by the
cooling system's heat dissipating capacity.  The later was thought to exert extraordinary pressure on the engine's gas sealing.

Apex seal lubrication has become a critical issue.  In a race engine, oil supply to the rotor housing by means of injection was precisely monitored and controlled, whereas in  the production unit, a larger amount is supplied, just to be on the safe side.  Some of the lubricant is fed into the trochoid chamber through a metering nozzle.  The previous nozzle's oil passage was 2.0 mm (0.08 in.) in diameter.  Negative pressure created in the rotor chamber would cause all the oil within the nozzle to be sucked out.
When the engine accelerated rapidly, oil supply could not keep up with the speed.  To prevent oil starvation, the previous system supplied a larger amount of oil to be on the safe side.  In the new metering nozzle, the passage diameter has been reduced to 0.08 mm (0.003 in.), halving its volume of 0.0005 L (0.03 cu. in.).  A new rubber seal is also inserted to fill a gap within the nozzle body where oil used to be sidetracked.  Now, there is still some oil left within the nozzle after each suction, so that the lubrication system responds to the apex seal's requirement.

In the exhaust system, the front tube gauge has been reduced by 0.5 to 1.0 mm (0.02 to 0.04 in.) so that flow passage is increased while retaining the tube's outer diameter.  The main silencer has also been redesigned.  These changes result in about a 10% reduction - about 13kPa (1.9 psi) - in exhaust gas resistance.

The third-generation RX-7 had come off Mazda's rigorous development test programs on the bench and on the demanding Global Road Circuit section of the Miyoshi Proving Ground with flying colors.  Yet, there was one arduous test left undone.  When the car was taken to a race track near Tokyo known
for its tight turns requiring short bursts of speed followed by fierce deceleration, the pride of Mazda's rotary rocket team quickly cooked its powerplant when pushed to the limit.  Subsequent investigation revealed that air temperature at the entry area had risen as high as 50 C (122 F).  Fresh air for the engine's consumption was taken from the single intake that also fed to the air-to-air intercooler.  On wide-open driving, air flow reversed its course from the intercooler and went straight into the engine's intake.
The intercooler was acting as an inter-heater!  In the updated RX-7 with a designed fascia, fresh air is taken through a separate, dedicated duct guided by a newly installed air-guide.  Air temperature at the engine's intake entry area has been halved to about 25 C ( 77 F), which adds about 7 kW (10bhp) to the output.

The front-end's opening areas have also been increased by factors of 2.1 for the radiator opening, 1.8 for the intercooler duct, 1.8 for the oil cooler, and 1.6 for the front brake cooling duct intake over the previous RX-7.  The radiator's core depth has been increased to 27 mm (1.1 in.) from the previous one's 25 mm (1 in.).  The 209 kW (280 bhp) engine had its fin-pitch changed from 1.1 mm (0.04 in.) to 1.3 mm (0.05 in.).  Twin cooling fans' blades have also been increased, one from five to seven blades and the other four to five blades, while the high-speed electric motors' consumption has been changed from 160W to 120W.

The central computing unit operates on the same logic;  however, its data parameters have been greatly increased.  The CPU centrally and precisely controls air/fuel ratio, ignition timing and boost pressure.  Mazda continues to offer the 194 kW (260 bhp) (and 190 kW (255 bhp) with automatic transmission) version of the 13B-REW, on the rational that not everybody wants 209 kW (280 bhp).  All external modifications are shared with the higher-power engine, except the turbos and oil metering nozzles.

On the chassis side, the updated RX-7's suspension has been recalibrated. There are three settings:  the RS, powered by the 209 kW (280 bhp) engine, the intermediate R, and the touring-type RB.  The RS is equipped with special Bilstein mono-tube shock absorbers.  Spring rates are shared by the three versions.

The RX-7 may now be fitted with an adjustable-rake rear wing with five alternate angles.  At the standard one-degree rake, the front lift coefficient is 0.045 and the rear 0.000.  At the extreme fourth setting of
14.5 degrees, The car generates a front lift coefficient of 0.053 and a negative rear lift coefficient of -0.075, pushing the rear end firmer onto the road surface.

When Kenichi Yamamoto, retired Mazda Chairman/President, began developing Felix Wankel's rotating piston engine in the early '60's, his Rotary Engine Research Department had 47 "samurais" (the number is the same as that in the group of real samurais revenging for their disgraced master in feudal Japan).  Over the decades, the division grew and then shrunk to a small team, now consisting of a handful of die-hard enthusiast-designers and engineers - all ten of them.

Would the faster RX-7 return to the American and European shores?  Unlikely, as the car has been absent from these markets where emission standards have been tightened, and in its current state, could not hope to realistically achieve.  Nevertheless, the rotary movement within the Hiroshima company, now a member of Ford Motor Co.'s global family, is showing signs of more management attention, and likely revitalization, as a symbol of Mazda's technological prowess.  Already, the development of a naturally aspirated, side-intake and exhaust port version of the engine is progressing well.  It will power a concept sports car to be revealed at the forthcoming Tokyo Motor Show.  The rotary is very much alive.

(The author of this article is Jack Yamaguchui, SAE Asian Editor.)
 

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