BX 4TC story
As a support car for the BX, Citroen launched the BX 4TC in the world championship rallies. Unfortunally the career of this lovely white car lasted only five months. A victim of a misadventure.
1986, the world championship rallies. For the last year, the rules set up by IFAS, the International Federation for Automobile Sports in 1982 allowed the famous B class cars to run. Extrapolated from a minimum series of 200 vehicles, these were wonderful racinf beasts said some, excessively dangerous monsters said others. Peugeot, the reigning champion already lined up an evolution 2 of its 205 Turbo 16 with an explosive weight-power ration, just like the Audi Quattro Sport, next to lancie with it's Delta S4, Ford with its RS1 and Ausin Rover with the Metro 6R4. In order to win the cocktail required, for twenty or so cars from the series 200 cars, is explosive: weight under one ton, 450 to 500 bhp on a racing car chassis. In 1986, the BX was at the end of its commercial maturity. Launched at the end of 1982 the BX met with quick succes thus ensuring Citroen's future following the 2CV, Visa and now declning CX. With its 7% of the market for this one model alone, the BX represented, in 1985, half of all firm sales. Thus encouraged Citroen launched the BX 4TC that threw itself into the world championship rallies. It passed the federations standards commission on the 1st january based on a series of 200 cars built by Heuliez along with 20 racing models. The career of this beautiful white car only lasted 5 months. As for those in the 200 series, they came to a discrete finish at the end of the next year.
B class and Citroen
1st january 1982..
The ne 'J annexe' created by the IFAS now came into force. It replaced the old class 2 and 4 categories with class A and B. The former, still in use today, concerns production line cars with at least four places made to a minimum series of 5000 cars in one year and restricted to limited modifications. The second class was much more liberal and only imposed a construction of 200 cars. This new classification pushed the big car manufacturers, wishing to win these rallies, to study a real race car that they could make as a series of 200. The first manufacturer to do this was Lancia with its 037 Rally with a Volumex compressor engine which lined up the first year with reconverted models from Class 4: R5 Turbo, Opel Ascona 400, Audi Quattro. With different means Guy Verrier, the head of Citroen's Competition department, launched the Visa Trophy. It came in as the poor mans B. Class' with its 1,285 cc engine with 100 bhp and standard feather weight of 730 kg, and managed to notch up quite a few honourable places in the hands on numerous drivers. Clearly this car was just the first step. Called to head the Competition Department by Jacques Wolgensinger, the head of Citroen's information and public relations, Guy Verrier was invested with a medium term objective: prepare the company for full participation in the 1985 world championships.
Februay 1983...
After Lancia and its 037 Rally which had just won the Monte-Carlo rally, Peugeot entered the scene with its unforgettable 205 Turbo 16. They had taken a leaf out of Lancia's book — central engine, suspension and structure of a race car — but with the added efficiency of four wheel drive. Its success was not only of a technical order: Peugeot managed the simultaneous launch of its production line 205 and its racing models, both these cars had certain advantages going for them. From their side, Citroen watched with satisfaction as the BX started its brilliant commercial career. At Trappes, 23 people worked constantly for the Competition Department. They insured the maintenance of the official driver's B Class Visas, support for the two Visa trophies, and the tests and tuning of a dozen different prototypes!
Unlike the choice made by Peugeot and other car manufacturer, Citroen engaged researchers from a whole range of racing staples. Lotus, Politecnic, Danielson, Strakit, Mokrycki, Dangel and Mathiot all played a part in the construction of the prototypes which were tested by the specialist company Philippe Wambergue. All the possible ways of installing the engine and transmission were tried, including a Visa with a PRV 6 cylinder engine with hydropneumatic suspension!
The choice of model which finally won the day at the end of 1983 wasin fact the simplest model, an evolution of the Visa Trophy modified with four wheel drive by D. Mathiot. Baptised Visa 1000 Pistes, this model was easy to industrialise and the construction of the 200 standardised cars undertaken by the coach builder Heuliez. In its 'evolution' version, it shone on the race tracks for several years. One could believe that during the year of 1983 Citroen focused all its efforts on the choice of one of its Visa prototypes. This is not so, because at the same time, the Competition Department had launched studies of two BX prototypes...
BIRTH OF THE BX 4X4 PROJECT
Why was there such a rush of studies and development of prototypes, especially in the two different branches with the Visa and the BX? Guy Verrier, explained Citroen's reasons in the magazine L'automobile in August 1983: 'In all sincerity, I must admit that we are still hesitating between the two. We could, in effect be different from our competitors by lining up with a small light car with 210 bhp (that could be the Visa). Or follow the fashion set by the other manufacturers and line up, like the others, with a car in the region of 960 kg (like most of the B Class cars). It would certainly be a BX 'To tell you the truth, our indecision is so strong that we have not ruled out the possibility of eventually manufacturing two different Class B versions.' The two BXs developed, exchanged the original U engine for a Chrysler 180 which, because it couldn't be installed transversally due to its size, was installed lengthways.
The first of the two BXs was prepared by Politecntc and presented very sophisticated solutions: 16 valve ROC cylinder heads. Hewland gear box using some of the cabin space in order to reduce to a minimum the weight of the engine at the front of the car. On the other hand, it had traditional McPherson suspension. The second, which was Guy Verrier's baby came from the Citroen workshops at Trappes. It had a turbo version Chrysler engine like the Peugeot 505 from the superproduction championships, SM gear box and hydropneumatic suspension. From then on the decisions started to come together in quick succession: Citroen lined up its Visa and Politechnic BX at the 1000 pistes rally (July 1983). The latter had to abandon in mid race and its future already written: the development of this model was stopped after its second race (the J-F Piot Trophy) and the prototype destroyed. While this was happening, the 'in-house' BX's development was being accelerated.
Studies quickly showed the impossibility of reliably developing a Visa 1000 Pistes whose supercharged engine would have provided the 250 bhp necessary to win the world championship trials. All on 1984 was consecrated to developing the BX 4x4 with the construction of three successive prototypes, one of which was exhibited at the Paris Motor Show that year under the name BX 4TC. Maybe because they had wanted to develop and test the different solutions, they did not meet their objective pf being ready for the 1985 world championship rallies. Another entire year was needed to industrialise and manufacture the series of 200 cars along with the 20 'evolution' models and get them through the IFAS standards commission, just in time, before the 1st of January 1986.
DEFINITION OF THE BX 4TC
An engine in longitudinal position at the front
When the choice was being made for installation of the parts, the car which would become the BX was the 11th model of the prototype launched by the Competition Department since 1981. Of the ten earlier models, seven had a central engine, identical to the installation which would be retained by most of Citroens competitors (Peugeot, Ford, Lancia, Rover). Why did Guy Verrier return to a more traditional front mounted engine? There are several explanations for this. Test results of the Visa 1000 Piste prototypes showed that an engine at the front was much more effective. Then, consideration had to be made for the manufacture and commercialisation of the 200 cars required by the Class B rules. Peugeot came a cropper over this stumbling block with its 205 Turbo 16. A BX 4 TC which kept the capacity of the original model offered a clear advantage. Choosing the body of the BX (with close front and rear mountings) made construction of a small series of 4 TC easier. This was an important point for the Competition Department's budget which was greatly less than that of Peugeot Sport. It must also be remembered that in 1984 the Audi Quattro was still - but for the last time - the reigning champion of the World Championship Rallies, with its longitudinal, front mounted engine and that Guy Verrier, a keen enthusiast of Citroens in rallies since the DS, then with the SM, was going to stick to his guns. There was however, a fundamental difference between a DS or SM engine behind the wheels or a Visa transversal engine and that of the BX 4 TC with an engine placed longitudinally at the front. Later on we will look at the disadvantages which would limit the choices of installation and the body.
AN ENGINE FROM POISSY
In 1984, there were three engines from the PSA organ bank which developed the 300 bhp and more required by a car hoping to win the trials in the world championship rallies. Firstly the V6 PRC, the installation of this engine in the BXs engine housing was structurally impossible. Then there was the XU family of engines which equipped the BX 1.6 litre and from which Peugeot had extrapolated the engine for the 205 Turbo 16. However, this engine was still being perfected so Guy Verrier was not too keen as he felt that it lacked the required cylinder capacity. Due to the image and identity of the make, Guy Verrier preferred to limit himself to choosing Citroen solutions - a controversial subject still going on today!
So, the only engine left was that of the good old four cylinder engine born to Simca in 1970, then mounted in the Chrysler 180, Matra Murena and then in the Peugeot 505 Turbo. Right from the start this was a modern engine, efficient and reliable. Overhead camshaft, light, well designed alloy cylinder head, cast iron engine housing. Several years earlier the preparation company ROC had made a successful development for Formula 2 racing: grafted onto a 16-valve cylinder head, this engine gave 300 bhp at 800 rpm! From 1983 it was used in the Peugeot 505 Turbo where it developed 150 bhp and performed brilliantly. Rumour has it that the turbo-compression version was perfected by Porsche. Still with its cylinder head with two valves per cylinder, this engine neared the 400 bhp mark for the Superproduction championship raced. The existence of this engine, available, not requiring special development for the BX 4 TC for the 200 series and apparently easy to soup up for the racing models was one of the deciding factor in the final choice.
The bore and course were however modified, to lower the cylinder capacity from 2,155 to 2,142cc so that is would not be higher than that of a 3 litre, once the variator corrector was linked to the turbo-compression. One original item is the electric compressor mounted on the turbo. This is a bit like the system presented by Lancia on the Delta S4 (Volumex compressor plus turbo). This installation make the turbo-compression more efficient by reducing the reaction time. Although the idea is very appealing in theory, in improvement is minimal as it is simply a CX heating ventilator. This system was used on all of the 200 production line cars but did not find its way to the race cars.
To be continued...
Credits:
Story by: Jean-Francois Pierre for Citropolis
Photos by: Communication Citroen, Euro-automobiles Heuliez, Laurent Bourengo
Thanx to: Mrs Mireille Gardon and Sylvie Bader (Citroen Phototec), Mr D Escarmant (Citroen's technical centre at Velizy), Patrice Roulois (President of the Euro-automobiles Heuliez directory), Marie-Therese Trouve (Euro-automobiles Heuliez) and Citroen drivers Dominique and Philippe Wambergue
