Ford developed a car based on the Sierra Cosworth chassis and mechanics but housed in an Escort looking outfit. Of course the Escort shell could not fit all these extra attributes i.e. north-south engine, four wheel drive, etc. so the chassis were sent from England to Germany were Karmann would cut, fit and re-adjust them so that Ford were able to put the Sierra parts in the Escort. Small changes were brought to the engine management system and a new, hybrid, turbocharger was fitted. You can check the street version's specs compared to the competition version here. Also available are the specs of my Escort RS Cosworth's compared to the street version here. You can also find lots of pictures of my car starting here. A grand total of 7'145 vehicles, all practically hand built, were produced between 1992 and early 1996. That's to say the Ford Escort RS Cosworth is a relatively rare car. The total production figure is equivalent to 4 days production of the Volkswagen Golf... Escort RS Cosworth production numbers (Kindly provided by John R. Bull of Ford's SVE division):
Two versions of the street Escort RS Cosworth were produced. The initial 2500 units were pure "homologation specials" used to get the FIA accreditation in group A and were fitted with an oversized Garrett T3/T04B turbo (this turbocharger is a hybrid consisting of a Garrett T04B compressor wheel combined with a Garrett T3 turbine and is also known as T35). This is the same device as the one fitted to the Ford RS200 GroupB car of old. These units displayed significant turbo lag due to the huge inertia introduced by the T35 unit and the detuned nature of their competition derived engine. The cars equipped with the T35 turbocharger cars used the YBT variation of the Cosworth engine (a total of 5'186 YBT engines were made). You can take a look at the YBT engine here . Among these initial units some, the ones denoted "Motorsport" versions, lacked the otherwise standard sunroof and rear tilting windows and had water injection equipment packed in a bag in the car's trunk (i.e. not mounted) so that the race cars could be fitted with it. A funny anecdote is that cars which would race in group N (production cars) could be checked to see if the water injection device was in their trunk (i.e. not fitted on the engine). Some competitors were not allowed to race in group N Escort RS Cosworth cars due to the absence of this non-functional equipment! The second generation of the Escort RS Cosworth was a bit more "civilized" than the first. The only exterior difference, compared to the "big turbo" version, was an HTT (High Torque Turbo) logo on both front doors. These cars, starting from late 1994, were fitted with a Garrett T25 turbo (much smaller than the huge T35, the T25 is using a T2 turbine and a T03 compressor wheel), the same turbo that was mounted on Fiat Uno Turbos! This engine was code named YBP. You can take a look at the YBP engine here and here. Note however that one could still order a "big turbo" Escort RS Cosworth while the HTT versions were in production. Major engine and engine management changes were also implemented. The Weber-Marelli IAW P8 management system was replaced by a Ford EEC IV unit which is much less versatile. The ignition system now had one coil per cylinder compared to the static ignition system found in the original version (no distributor is used). Bigger oil projectors were placed under the piston heads for cooling purposes and a new engine head design was applied. By applying all these modifications Ford hoped to be able to sell more cars since in the HTT version the turbo lag time was dramatically reduced as compared to the T35 based version and the cars were easier to drive in everyday traffic conditions. Note, however, that not only the T25 turbocharger's output drops significantly above 5'500 RPM but that the aftermarket modifications, so common on Marelli based ECUs, were much harder to implement properly on the much more restrictive EEC-IV unit. I think the shift from the big turbo to the small turbo version was a pure marketing trick which, as always, does not take into consideration the motivations of the real buyer base. This breed of car is bought by enthusiasts to whom turbo lag, engine responsiveness in low revs, or even harshness are not very relevant. The Ford
Cosworth series of cars (Sierra, RS500, Sapphire, Escort) share a number of components and
technical solutions that grant them a common family feeling. The front McPherson struts use a lower track control arm which, although adequate in less powerful cars, quickly shows its limits in the Cosworth series. A lower wishbone would have been a much wiser choice here. Note that the front anti-roll bar is also connected to the strut and is thus used as a secondary control arm but still one feels the need for more precision and control in sudden direction changes. The competition versions used a similar design with titanium parts (hubs and control arms) but the relocated attachment points and altered geometry allowed for better control and feel of the front drivetrain. At the back we find another classic Ford solution of those days with the use of a McPherson strut this time using trailing arms, transversally mounted, which provide adequate wheel control. Here the main problem lies with the design of the control arms and whole suspension structure which are made in steel tube, of variable almost square section. The tubes are made of seam welded steel sheets. The whole rear suspension is connected to the car's chassis through another steel tube structure which is fitted on the chassis by rubber bushes. As you see the main rear suspension problems are: rigidity (its absence rather, especially when the bushes are used) and its tendency to deformation (under extremely high stress or when hitting curbs the steel tube structure may bend). In short, although no revolutionary solutions were used in the suspension of the car, the standard Cosworth will provide adequate handling and control in all but the most extreme situations. ©Copyright 1996-2008 Tryphon Georgallides, all rights reserved; |
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