Ford Escort RS1700T – Group B Prototype

Published on: Jan 18, 2016 @ 18:00
Originally Published in: 2015 (old website)
(C) Jay Auger - website owner & author
Notice: Any form of duplication methods (including but not limited to copy/paste of text and screen capture) of the website's content is strictly forbidden.

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In the late 1970s, talks by the FISA of major upcoming sporting regulations changes, especially the Group B proposition, made Ford seriously re-evaluate their future in rallying. Their venerable Escort, albeit a mainstay in competitive rallying, was on the verge of a major change. As such, after winning the WRC titles in 1979, Ford surprised everyone and sold everything to the privateer David Sutton team so they could concentrate on developing a brand new rally car that would be up to snuff with the upcoming Group B regulations. After a short lived study with a much modified Fiesta, Ford would base their definitive new rally weapon on the soon to be launched third generation Escort.

1981-ford-escort
The third generation Ford Escort (MkIII) World Car “Built to take on the world”

Contrary to its predecessors, the new generation of the Escort was to be front wheel drive from the factory. However, the team at Boreham knew that front wheel drive wouldn’t handle the power needed to win international rallies. However, Group B’s much looser rules, which were planned to take effect in 1982, would allow new design opportunities. The engineers came with a “silhouette” rally car by dropping the MkIII Escort body on a custom designed rear wheel drive chassis. Ford can be credited as being the first to go in such a route for a rally car.

The project, originally code-named as “Columbia”, was thus born and timetables quickly set; Ford’s upper management had planned for the car to begin testing as soon as mid-1982 and tackle a complete WRC programme for 1983. However, unbeknownst to Ford, all the meanwhile Audi introduced their four wheel drive quattro rally car. After the Audi’s first outings, Ford weren’t too worried since the quattro turned out to be unreliable and clunky to drive despite its traction advantage. Thus, the Boreham team still continued building their rear wheel drive Group B rally car.

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Technical view

The previous MkII Escort was a highly successful rally car so the engineers designed the new chassis to share many underpinnings with that model. It was common practice to start with something familiar and proven. Similarly, again in partnership with Cosworth, Ford went back and used the 2.0 BDA engine from the previous rally car. However, the new unit would undergo several revisions such as reducing the displacement to 1778 cc and adding the very critical turbocharging system. This was explicitly done to maximize the 2000~2500 cc class of the new Group B regulations, which demanded a multiplication factor of 1.4 for forced induction engines (1778 cc x 1.4 = 2489 cc), and would allow the car to weigh as little as 890 kg (1960 lb). In doing so, Ford had created the powerful BDT engine: a unit that was originally expected to reliably achieve anywhere between 250 to 350 HP. Although the engine was officially a 1.8L, Ford decided to use the “RS1700T” moniker to differentiate the new rally car from the previous generation RS1800 model.

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The BDT engine

Later on, the team considered using an alternate “RS2300” powerplant: a 300 horsepower, normally-aspirated, 2290 cc 420R-code F2 engine developed by Formula engine designer Brian Hart.

Since the engines were to be mounted in the front and longitudinal position, weight distribution became a huge concern, so the engineers had the idea to use a rear transaxle system to better the weight bias. This is where the experience of John Wheeler came into play since he had previously worked in the development of the Porsche 928: a car also sporting a front engine and rear transaxle. Wheeler’s expertise would also see that the long driveshaft between the engine and transaxle be replaced by an aluminium torque tube which greatly helped in overall chassis rigidity. Other important improvements to the rally cars featured central locking wheels, like a circuit race car, to allow for quicker tire changes. Such new technologies and different setups considerations meant that the project was plagued with a lot of technical problems and delays.

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Forefront : “Hart” powered prototype / Background: “BDT” powered prototype

There was a lot of pressure on the Boreham team to start showing results of the project so, six weeks before the planned first test at the 1982 Tour de Corse, they rushed preparations of two cars (one RS1700T and one RS2300 “Hart”) to begin testing in the Portugal rally instead. That event would also allow Ford to pit the car in direct competition with the four wheel drive Audi quattro and compare stage times on gravel.

For this, they enlisted the help of drivers Ari Vatanen and Pentti Airikkala to test the cars. After the event, Vatanen gave a negative review of the “Hart” powered car. On the other hand, the BDT equipped version ran 1.5 seconds per kilometre faster than the Fiat Abarth 131 that had won the previous year, which would give the final “thumbs up” to develop the definitive rally car around the BDT engine. The final review of the event was seen as positive, although the cars seemed to struggle to match pace with the Audi quattro’s times, so morale within the Ford team was still high and optimistic.

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In fact, plans to begin production of the 200 homologation units at the Saarlouis plant in Germany were in the final phase when the news came from Ford’s upper management that they now wanted a four wheel drive car. Upon advice from the engineers, Ford originally approved a two-step program for the RS1700T; for the 1983 season, they would go forward competing with the rear wheel drive version while developing a four wheel drive system, then produce a second batch of 200 homologation cars (these would be four wheel drive) which should be ready to compete in 1984. A few months later, Ford appointed a new motorsport director, Stuart Turner, who would scrap all the plans for the RS1700T in favour of developing a brand new car from scratch.

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For the Ford RallyeSport team, this meant losing over two years of hard work on the RS1700T (of which 18 prototypes were already built). This prompted much frustration within the Boreham based team. However, not all efforts were in vain as many of the RS1700T’s features would carry over to the new car, including the Cosworth BDT unit (the 200 homologation engines were already built) that went on to power the replacement car, the now famous RS200. It is easy to argue that, if not for the new four wheel drive standard, the RS1700T would have definitely been the car to beat in the WRC.

The remaining RS1700Ts and spare parts were sold to Ford South Africa for use in the country’s rallies (which did not require homologation) and were rebranded as the “Escort RST” (RallyeSport Turbo). Even there, the rear wheel drive Escorts were hardly able to match the fleet of local Audi quattros, but some did manage to “steal” a few podiums.

RST on display at the 2016 Eifel Rallye Festival

SPECIFICATIONS

Group/Class B/12 PROTOTYPE
Conception/Production 1980~1982  # built: 18
Engine
Type
  • RS1700T: Cosworth BDT, I-4, DOHC 16v, gas
  • RS2300: Hart 420R, I-4, DOHC, 16v, gas
located front longitudinal
Displacement
  • RS1700T: 1778 cc
  • RS2300: 2290 cc
WRC x 1.4 forced induction factor

  • RS1700T: 2489 cc
  • RS2300: no change
Compression ratio
  • N/A
Output power – torque
  • RS1700T: 320 HP @ – rpm
  • RS2300: 300 HP @ – rpm
  • RS1700T: 380 lb-ft @ – rpm
  • RS2300: 241 lb-ft @ – rpm
Materials block: aluminium (RS1700T) cylinder head: aluminium (RS1700T)
Aspiration
  • Garrett T3 turbocharger (RS1700T)
  • Normal/Natural (RS2300)
  • Bosch Jetronic fuel injection (RS1700T)
boost: N/A
Ignition electronic / firing order 1-3-4-2
Cooling system water-cooled
Lubrication system N/A
Transmission
Type rear wheel drive Hewland 5 speed transaxle
Gearbox ratios
  • N/A
  • N/A
Differential ratio N/A
  • self-locking differential
Clutch N/A
Chassis-body
Type Modified Escort XRi3 steel monocoque chassis, converted from FWD to RWD, MkIII Escort bodywork composed of steel and fiberglass, widened fender flares, rear spoiler
Front suspension McPherson type struts, Bilstein shocks
Rear suspension McPherson type struts, Bilstein shocks
Steering system rack and pinion N/A
Brakes Front and Rear: AP 4 pot calipers, vented discs adjustable F/R brake ratio
Dimensions
length: 3970 mm (156.3 in) width: 1740 mm (68.5 in) height: 1385 mm (54.5 in)
wheelbase: 2395 mm (94.3 in) front track: N/A rear track: N/A
Rims – tires centre-lock wheels
  • N/A
Dry/Unladen Weight
  • RS1700T: 890 kg (2260 lb)
  • RS2300: 910 kg (2310 lb)
Weight/power N/A
Fuel tank N/A

VIDEOS


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(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

Special Thanks:

  • Bill Munro (picture)

NOTE: An older & abridged version of this page’s article was proudly featured in the February 2017 issue of Pacenotes Rally Magazine!

feb-2017-issue

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