A lot has changed through the years of development. As fitted to the 1974
Extreme custom Upgrade of a RX7 Rotary Turbocharged engine.
The fire in the
downfall of other sequential twin turbo systems is the
transition from single to double operation. This is due to the
second turbo not spinning fast enough when its called on,
resulting in the engine “coughing” momentarily. Mazda solved
this problem by spooling the second turbo to a pre-boost speed
of around 100,000 rpm with exhaust gas circulation. When the
time comes for the second turbo to cut in, a by-pass valve is
shut to “surge” the compressor, spinning it to over 140,000 rpm.
This then assures a smooth coupling with the primary turbo. Once
at the required speed, it receives a full share of exhaust flow
to add its boost with the primary turbo. The twin turbo
chargers are fitted to a “dynamic pressure” cast iron exhaust
manifold shaped to minimise the gap between the exhaust ports
and the intake of the turbos, improving boost by as much as 35
per cent. The 13B-REW was fitted standard with an air-to-air
intercooler mounted above the radiator with separate ducting.
controlled fuel injection system uses air density measurement
instead of the common air flow metering to allow a smoother air
flow and more precise fuel management. Coupled with the precise
shape of the plenum chamber and inlet tract length, the added
benefit of the increased power and throttle response is the
additional improvement in fuel consumption for the city/highway
cycle. Two injectors
per rotor look after the varied engine loads. The primary
injector takes fuel from the side of the injector body instead
of the top. The resulting reduction in fuel travel through the
injector body gives a quicker and more precise engine re-start
after high speed/load applications. The secondary injector is
mounted upstream of the inlet tract operating during mid and
high rpm. Change over to twin injector operation takes place
around 2,750 rpm or lower if the load commands it. Ignition timing
of the four platinum tipped spark plugs (two per rotor) is
controlled via the ECU which will automatically retard timing if
detonation is detected. Light weight high energy coils are
utilised to take advantage of the rotary’s unique combustion
characteristics. Ensuring the
emissions are lower than required, the use of a two stage
catalyst system were the main three way converter gives the
lowest flow resistance available. A single muffler is used for
noise reduction and the whole system weighs considerably less
compared to the series V RX-7.
RENESIS – The
|At the Tokyo
Motor Show in October 1999 Mazda Motor Corporation unveiled the
RX-Evolv, a concept vehicle which later evolved into the RX-8
four door, four seat sports car which was unveiled in January
2001 at the North American International Auto Show (NAIAS) in
Detroit and then into the production model that appeared at the
October 2001 Tokyo Motor Show.Both the Evolv and
the RX-8 had many things in common, not the least of which was
the latest version of the rotary engine called “RENESIS.”The RX-8 with
its RENESIS rotary engine made its debut on Australian roads in
naturally-aspirated engine revs eagerly to extremely high engine
speeds while producing racecar-like power and performance. “RENESIS”
stands for “The RE (Rotary Engine)’s GENESIS”, or the rotary
engine for the new millennium.The RENESIS
engine is improved from the 13B rotary engine used in the RX-7.
Refinements include positioning the exhaust and intake ports on
the side housing, separate from the rotor housing. This reduces
overlap between the opening of the intake and exhaust ports,
stabilizing combustion. At the same time, it enables the intake
port to be enlarged, increasing engine rotational speeds and
power output to levels never-before achieved with a naturally
aspirated production rotary engine. Other refinements, including
thinner, lightweight rotors, thicker eccentric shaft, and a
three-port, three-stage variable intake system, contribute to
the engine’s maximum power output of 177kW at 8,200 rpm, maximum
torque of 211Nm at 5,500 rpm and a 10,000 rpm redline for the 6
speed manual and a maximum power output of 141kW at 7,000 rpm,
maximum torque of 220Nm at.5,000 rpm for the activematic.A new, compact
wet-sump oil lubrication system, making use of the unique layout
of the output shaft, and a thin oil pan contribute to the
engine’s lightweight compact design, which allows the engine to
be located lower and further to the rear than ever before. For
rotary engine enthusiasts, the next exciting phase in the great
engine’s history has already begun.
|New 929 and
facelifted MPV models released. 12 hour endurance race moved to
Eastern Creek and RX-7 again wins, beating Porsche.
|Eunos 800 with
unique Miller Cycle engine, new 323 range including Astina Hatch
and Hardtop and Protegé released. RX-7 again beats Porsche in 12
Hour race at Bathurst.
|RX-7 wins 12 hour
endurance race at Bathurst beating arch-rival Porsche. MPV
“people mover” with 3.0 litre V6 engine, and facelifted MX-5
with 1.8 litre engine released.
|New twin turbo RX7
released and wins 12 hour endurance race at Bathurst. V6 626
Sedan added to the range. Eunos division and stand alone dealer
network launched and offers Eunos 500 and 30X models. 500 is 2.0
litre V6 Sedan and 30X 1.8 litre V6 sports coupe. Jack High
recommences and is telecast on national Nine Network. 250,000th
|New 121 series
Hatchback, B2600 series utilities and pick-up, 929 3 litre V6
Sedan and Hardtop, 626 and MX-6 Turbo Coupe and RX-7 Convertible
released. Mazda Australia begins component export programme with
shipment of Ballarat-made Timken bearings to Japan.
|The 300,000th Mazda
imported to Australia, a new RX-7 rotary.
The distinctive note of
the Mazda rotary engine has been heard along pitlanes as far afield as
Daytona, Nurburgring and Mount Panorama. This compact, light but
powerful engine has proven to ideally suited to the high-stress
environment of track and road racing.
However, Mazda has also tasted success with other models, with its 4WD
323 winning the Australian Rally Championship in the late 1980s.
Targa Tasmania 2002
Mazda’s rotary engine technology was again in the spotlight with an RX-7
SP tackling the gruelling Targa Tasmania 2002 rally.
The RX-7 SP, which competed in Targa with exotic cars from around the
world including the latest generation Porsche turbos, was the same car
that won the 1995 Eastern Creek 12 Hour production car race.
An all-new generation rotary engine, dubbed RENESIS, will power the new
four-seat RX-8. The new RENESIS engine, which will meet the world’s
toughest emission standards, develops 184kW at 8500rpm and 220Nm at