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On the 13th of January at Ford's Engineering and Research Centre in Essex the covers were pulled off the Stewart team's 1998 challenger, the SF-2. While it bears a superficial resemblance to the SF-1 the new car represents a significant advancement over its predecessor in terms of its aerodynamics and under-the-skin technology.
The SF-2 features a number of innovations designed to combat the disadvantages of the new regulations for slimmer chassis, not least being a ground-breaking, super-slim carbon-fibre gearbox which allows a narrower "Coke bottle"-shaped rear end. The team have optimised weight distribution by situating the oil tank in front of the engine and the car also features all-carbon-fibre suspension, mounted on knife edges and multi-linked at the rear to offset the effects of the narrower track under acceleration and braking. The housing of the torsion bars also gives the car a distinctive "horned" appearance.
| Chassis | Composite monocoque structure, designed and built in-house, carrying Ford V10 engine as fully stressed member. |
| Engine | Ford Zetec-R V10 |
| Transmission | Stewart carbon-cased six-speed gearbox, longitudinally mounted. High-pressure hydraulic system for power shift and clutch operation. AP Racing triple-plate pull-type clutch. Integrated oil system. |
| Front suspension | Upper and lower carbon wishbones and pushrods. Torsion bar springing. Triple Stewart/Penske damper lay-out. |
| Rear suspension | Upper and lower fabricated steel multi-link. Torsion bar springing. Triple Stewart/Penske damper lay-out. |
| Brakes | AP Racing lithium alloy six-piston caliper. Carbone Industrie carbon fiber discs and pads. |
| Front wheels | 12" x 13" BBS forged magnesium |
| Rear wheels | 13.4" x 13" BBS forged magnesium |
| Tyres | Bridgestone |
The reliability of the Zetec-R V10 engine was definitely the weak point of the package in 1997, and Ford and engine builder Cosworth have collaborated closely with Stewart to produce a completely re-packaged engine which they are confident will compare favourably in terms of power and driveability with the likes of Peugeot, Ferrari and Mecachrome. The next step will most likely be to run the engine hotter and allow the use of smaller radiators, a development a couple of other engine manufacturers are taking on board. The new engine also features gear-driven systems in place of the chain-drive that caused such problems last year.
| Cylinders | 10 in a 72-degree V |
| Valves | 40 |
| Capacity | 2998cc |
| Length | 605mm |
| Width | 520mm |
| Height | 460mm |
| Weight | 120kg |
Once again, the Stewart team will be running their cars on Bridgestone tyres, grooved to comply with the new regulations. Plans for the new Stewart test team include a deeper collaboration with the Bridgestone development programme.
