Mazda RX7 Group S Prototype
In 1985, the FISA (former ruling committee of the FIA) announced a possible replacement class to Group B that was referred to as “Group S”. The new regulations would require only 10 cars for homologation and was essentially a “prototype” class for rallying. The class was originally scheduled to make its debut on January 1st 1988, then as a heavily revised replacement to Group B for 1987, but both were ultimately cancelled. To learn much more about the history of Group S, please CLICK HERE!
Very few people knew that Madza had actually toyed with the idea of joining Group S, especially since their rear wheel drive Group B RX7 never was very successful (less its 3rd place finish at the 1985 Acropolis Rally highlight), that is until the car was widely seen at the Nostalgic 2 Days Japanese auto show in 2014. Built by Mazda Rally Team Europe (MRTE) in Belgium somewhere in 1986, the prototype features a space-frame chassis with a body very loosely based on the new generation FC3S RX7 of the time period.
Powering this car is a 3-rotor 13G naturally aspirated rotary engine (precursor to the 20B) sourced from the Mazdaspeed 757 LeMans racer which produced around 450 HP. Since the engine was very compact it was able to be mounted in a front-midship position for better weight distribution.
What may be considered as the biggest departure from the Group B car is that the Group S prototype features four wheel drive and most strikingly four wheel steering. Details about the 4WD system and differentials used are unknown. However, a small adjustment lever next to the shifter in the cabin seem to indicate it had locking and/or ratio altering capabilities. Suspension is handled by double wishbones and dual dampers at every corner.
The wide body features lightweight composite construction with front and rear opening clamshells. Very subtle air scoops can be found on both sides of the pillars which seem to provide air to small twin coolers (transmission / differentials most likely). A roof scoop provides air to a rather large engine oil cooler. The radiator itself remains in the nose of the car with cooling aided by a bonnet/hood vent/extractor. A scoop provides fresh air to the intake. The car also features a mono (single) wiper setup that looks very similar to units used on the Mercedes W210 CLK a whole decade later. It is unknown if the wiper system is in fact original to the car or was later added to it.
Two prototypes are rumored to have been built. It is unknown if they are identical or have different features. What is certain is that, if Group B & S wouldn’t have folded, this car would have provided the fans with a sight and sound spectacle like no other!
|Production||1986||# built: 2 (rumored)|
|Type||13B G3, Wankel 3 rotors, peripheral ported, gas||front mid-mounted|
|Output power – torque||450 HP @ 8500 rpm||289 lb-ft @ 8000 rpm|
|Materials||block: N/A||cylinder head: N/A|
|Aspiration||naturally aspirated||variable lenght intake|
|Ignition & Injection||
|Lubrication system||dry sump with rear mounted reservoir and roof mounted cooler|
|Type||four wheel drive||5-speed manual transmission (presumed)|
||driver controlled variable locking center differential ratios|
|Front suspension||Double wishbones, Dual shock absorbers, anti-roll bar|
|Rear suspension||Double wishbones, Dual shock absorbers, anti-roll bar|
|Steering system||rack and pinion||four wheel steering system|
||dual circuit with servo|
|length: N/A||width: N/A||height: N/A|
|wheelbase: N/A||front track: N/A||rear track: N/A|
|Rims – tires||
|Dry/Unladen Weight||950 kg (2100 lb) *estimated||Bias:N/A|
|Weight/power||2.1 Kg / HP (4.7 HP / lb)|
(C) Article by Jay Auger – website owner & author
- Images & videos are the property of their original owners
- Eifel Rallye Festival Pictures used under permission – McKlein Publishing
- This website is not affiliated with any entity listed in this page
- partial info & pictures: http://www.speedhunters.com/2014/02/nostalgic-2-days-spotlights/
- videos (edited): YouTube user “GAKU2WEB” / https://www.youtube.com/watch?v=Rqczp5kV5jM & YouTube user “maztec7” / https://www.youtube.com/watch?v=eI8IrSGYC2Q
SPECIAL THANKS TO:
- Phillip Kruger
- Leo Rossi
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