In developing the Ford Focus RS WRC 07, BP-Ford World Rally Team's technical director Christian Loriaux and his team did not seek to take huge steps forward because such leaps are impossible under the regulations. Instead they concentrated on making minor, but significant, developments in several areas. Here are the key technical changes along with Loriaux's thoughts on the improvements that he and his team of engineers developed:
Engine
Although the Focus ST model on which the World Rally Car is based uses a 2.5-litre, five-cylinder engine, rallying rules do not permit an engine of that size. However, the regulations do allow teams to use another engine from elsewhere in the Ford Focus model range, so when designing the 2006-specifcation car M-Sport opted for the 2.0-litre Duratec unit, with the addition of a turbocharger and the mandatory 34mm inlet restrictor. That engine, which has an all-alloy block, remains in the 2007 car.
- The changes on the new car are mainly to save weight and to improve efficiency, driveability and performance at the bottom end of the range, said Loriaux.
It has a lighter flywheel while further machining of the engine block has removed unnecessary parts and weight has also been saved by lightening some internal parts of the engine. The car also contains a new exhaust manifold, the former two-piece system replaced by a single-piece unit.
Engine specifications:
- Ford 1998cc Pipo built I4 Duratec WRC engine.
- Four cylinders, 16 valves.
- Bore: 85mm. Stroke: 88mm.
- Pi electronic engine management system.
- Turbo: Garrett turbocharger (with FIA required 34 mm inlet restrictor).
- Air intercooler. Catalytic converter.
- Power: 300 bhp at 6000 rpm
- Torque: 550 Nm at 4000 rpm
Suspension
The Focus RS WRC 07’s suspension is virtually identical to that of the 2006 car. It continues to use Reiger dampers and the only change is a small weight reduction on various components.
Suspension specifications:
- Front and rear: MacPherson struts (front) and Trailing-Arm (rear)
- Reiger external reservoir dampers, adjustable in bump and rebound. Fully adjustable fabricated steel links.
- Front and rear anti-roll bars. Cast steel uprights. Ceramic wheel bearings.
Bodyshell
The bodyshell displays visible changes at both the front and the rear. The rear wing has been modified to improve the car's aerodynamic efficiency.
- It's a new wing and although it is not radically different from the 2006 car, it should reduce drag, said Loriaux.
At the front, the car sports a new bumper which has been raised to improve ground clearance.
- The previous bumper was too low, mainly because when we designed the previous car we didn't have enough time to test alternatives before homologation. As a result gravel was often scooped up onto the bonnet and windscreen which was irritating for the drivers. By raising the height we should eliminate this and also reduce the amount of damage we've suffered to the bumper, he added.
The other visible change is that the side exits to the front bumper for cooling are now vertical instead of horizontal. The shell has also been modified slightly to increase the protection offered to the co-driver.
- We've made a small change so that we can use a seat with safety ears for the co-driver. It adds a further degree of safety which has always had the highest priority in our design, explained Loriaux.
Transmission
The Ford Focus RS WRC 06 featured considerable changes to its gearbox from the previous model, not only in specification but also in layout. The original Focus WRC (introduced in 1999) mated a longitudinal gearbox to a transverse engine, an engineering feat in itself. But for the 06 car Loriaux used a transverse gearbox along with the transverse engine. He has made no alterations to that but has still achieved a weight reduction in the gearbox and more development is planned.
- We're working on trying to improve the gearchange speed. We have homologated new parts but have not done sufficient work to introduce them onto the car yet. That is for the future, said Loriaux.
Transmission specifications:
Permanent four-wheel drive with M-Sport designed active centre differential. Pi electronic differential control units. M-Sport / Ricardo five speed sequential gearbox with electro-hydraulically controlled shift. M-Sport / Sachs multi disc carbon clutch.
Weight distribution
Loriaux is renowned for his innovative design approach to lowering the centre of gravity in rally machinery. Many of the trends seen on today’s cars, such as the crew sitting particularly low in the cabin, can be attributed to his earlier designs. Having set new trends on the 06 car, Loriaux has continued to concentrate on saving weight and no element of the car has escaped intense scrutiny in this area. Weight has been saved in the engine, suspension and transmission.
- The engine is about 5kg lighter, which is a figure I'm really happy with. It's a lot to save. It's another 5kg that we can transfer to another area of the car to improve its balance and handling, told Loriaux.
Savings have also been made by redesigning the pedal box, the hydraulic jack and even the wheel brace.
Brakes:
- Gravel (front and rear): 300mm Brembo ventilated discs with Brembo four piston monoblock calipers.
- Asphalt (front and rear): 370mm Brembo ventilated discs with Brembo eight-piston monoblock calipers.
- Hydraulic handbrake; Adjustable front / rear bias.
Steering:
Power-assisted high-ratio (12:1) rack and pinion. One and a half turns lock to lock.
Wheels:
- Gravel: 7in x 15in (magnesium) wheels with BF Goodrich 650mm tyres.
- Asphalt: 8in x 18in (magnesium) wheels with BF Goodrich 650mm tyres.
Electronics:
Full Pi chassis and engine data acquisition for on-event diagnostics and performance development.
Fuel tank:
FIA FT3 tank, 94 litre capacity, located centrally.
Dimensions:
Length: 4362mm. Width: 1800mm. Wheelbase: 2640mm. Weight: 1230kg minimum.
Finland tests with Mikko Hirvonen
-Mikko Hirvonen/BP Ford World Rally Team
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