The Ford Focus WRC - Part 3

As mentioned earlier the Cosworth power unit has been dropped and replaced by a turbocharged (with no street equivalent) version of the Ford Zetec E 16V engine. Many interesting features are included in the new unit. Unlike its predecessor the Focus WRC uses a transversal engine layout. To improve weight distribution and air intake conditions the engine is inclined by 25° to the rear as compared to the street versions of the Focus. This of course is allowed by WRC class car regulations. The turbocharger used is a TR30 R Garrett AiResearch unit (the Escort WRC used an IHI) which was developed specifically for this application. The TR30 R is a race derivative of the "old" Garrett T3 turbocharger but uses an extremely expensive Mar-M 247  (this nickel-based super alloy is a trademark of Martin Marietta Corporation which became part of Lockheed Martin Inc. in 1995) turbine wheel instead of the INCONEL alloy turbine of its predecessor and has revised geometry to better accommodate the 34mm intake restrictor. All turbo calculations and dimensioning were done with an integrated 34mm restrictor as specified in FIA regulations. The previous Ford contender, the Escort RS Cosworth was using an earlier generation Garrett turbocharger. The Focus WRC car specs are here.

The Focus Zetec turbocharged unit

As you can see from the picture above the exhaust manifold is specific to the Focus WRC application and is quite long, reminding the one used in the RS500 homologation special of the 80s. Long exhaust manifolds allow for a greater quality of gas flow to the turbocharger but have the inconvenience of introducing a relatively important amount of turbo lag. Surely Ford took care of this downside by using the latest generation of turbo anti-lag systems (ALS) on their engine. The exhaust tubing is made out of the precious INCONEL alloy which is very light and heat resistant. Note also that ALS systems seem to be disappearing from the rallying world. Many new teams avoid using them for reliability reasons. These include Toyota and Seat. The engine and more specifically its water pump is what caused major trouble on the first official entry of the Ford Focus. The commissioners of the 1999 Monte Carlo rally refused to accept the car because its water pump was located off the engine in a remote location and was providing independent water flows to each cylinder. This configuration was not part of the FIA homologation sheet Ford had submitted and the team was allowed to race the car after appealing and getting the support of all the other major competitors except Subaru. During the 1999 season the Focus WRC engines were prepared for racing by Mountune. As of the 2000 season the engines are be built and prepared at the Cosworth Racing premises. Many of the Focus WRC engine, transmission and suspension parts are manufactured by the Italian specialist L. M. Gianetti, the choice of an Italian company is certainly related to Steiner himself being Italian.

The Focus follows the current trend in World Rallying which is the "smaller the better". Most of  the latest contenders in the WRC introduce very compact cars. This is the case for both Toyota and Peugeot. The Focus is a very compact car with a relatively important wheelbase compared to its length and thus very reduced overhangs. The front and rear tracks are at the limit of what the WRC class allows which is 1550mm. We already spoke about the rear suspension previously so lets have a look at what the front suspension holds. A classic McPherson strut is used with lower wishbones. The layout is pictured below. As you see the strut is very compact and leaves more space to fit other car components around it.

Although this design does not seem revolutionary at first glance it is interesting to note that the dampers have more than the classic adjustable parameters. Usually rally cars use dampers which are adjustable separately for compression and rebound. This is the also the case for the Focus WRC. Ford, however, added new adjustable parameters in their latest dampers. Dampers can now be adjusted depending on the frequency of their piston's movement in the damper core. To put it more clearly the dampers have different damping characteristics when low frequency movements of the suspension occurs (these are typically related with chassis to damper core vibrations) and different damping characteristics when high frequency movements occur (typically wheel to damper core vibrations). This feature allows for a much more precise handling adjustment. The Reiger dampers used on the Focus WRC use a separate, remote, nitrogen tank which you can see in the picture above (in purple color).

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