Lancia Delta S4 Road Car

- After the advantages of 4WD became apparent, Lancia seeked to overcome the limitations of the front-heavy Quattro, and at the same time more fully exploit the new Group B rally class, by designing a 4WD mid-engine lightweight rally car from scratch.

- Only 200 were made as per Group B Rally homologation requirements.

- The car utilized a turbocharger in series with a positive-displacement supercharger.

- This was to combat the un-niceties of the peaky torque curve which was the usually the result of fitting a high-pressure turbocharger in a low-compression engine.

- Custom tubular chromium-molybdenum (chromoly) steel spaceframe and box-section chassis.

- The engine radiator was mounted at the front?

- The cooling air for the large rear-mounted intercoolers was directed in from the rear quarter windows and from the roof scoop. The air proceeded to flow through the horizontally mounted intercoolers on its way to the low pressure zone underneath them.

- The race version scooped breathing air from the roof, while the road car sucked air in from the side panel.

- The race version had a top mounted oil cooler?, to take advantage of the efficient roof-mounted air scoop. The air filter and intake pipe also extended upward into the roof-scoop. In order to improve the rear visibility of the road car, the oil cooler was relocated, and the air filter was lowered, with the intake pipe now leading toward a hole in the left rear side panel.

- The fuel tank was saddle-shaped, with half on each side swallowing the space under the seats, and the other half just behind them. The fuel filler was located just in front of the right rear wheel, and could only be accessed by lifting the rear hatch.

- Of the two exhaust pipes protruding from the rear of the race version, one was the conventional exhaust outlet, and the other came directly from the wastegate. In order to reduce noise in the road car, the wastegate outlet was fed through the racing (type?) muffler.

- Pneumatically assisted power steering.

- Epicyclic centre differential to deliver torque anywhere from 25% front, 75% rear to 40% front, 60% rear.

- EVO 2 featured water injection.

- Suede (actually alcantara) interior for the road car.

- Electronic fuel injection and ignition.

- Aluminum block and ceramic (nitrided?) aluminum cylinder liners.

- Two intercoolers; the left one for the turbo; mounted transversely, and the right one for the supercharger; mounted longitudinally (as seen from behind).

- 7:1 (or 7.6:1 ?) compression even for the road car, and this meant power could be easily lifted from 250hp to ~400hp.

- Quote from http://www.walkersgarage.co.uk/s4_new.htm "The transmission system was very interesting. The gearbox (in front of the engine) transmitted drive to a central differential through step-down spur gears. Transmission from the central to the rear differential was by rigid axle and to the front differential by a second axle with homokinetic couplings. The torque split by the central differential could vary from 75/25 rear/forward to 60/40 - to suit different traction conditions.".

- The whole rear section lifted up like a clamshell to expose the mid-mounted inline 1800cc 4-cylinder engine, which drove a central differential through a forward mounted transmission.

- The front section also tilted forward dramatically to expose the front suspension, spare wheel, and at the front, the radiator.

- Titanium axles on the race version, but conventional steel ones on the road car.

- Road car equipped with (one of the first?) asymmetrical Pirelli tires.

- The cockpit could get very hot, due to the engine being just behind the front seats, and heat also leaked from the transmission, which sat between them.

- Lightweight plexiglass? slide-type side windows.

- The 4WD system was fairly conventional; in layout it appears similar to that of the Jensen Ferguson Formula; only backwards, considering the Lancia is mid-engined.

- Although there appears to be some useable space above the engine, in practice, in order to provide adequate airflow to the intercoolers this whole area was pressure fed by the top and side mounted air scoops, and was therefore sealed off from the cockpit by a plexiglass? window. There were also additional slots to provide air into the engine bay from this high-pressure zone.

- Instrumentation was generous, and featured a centrally mounted boost pressure gauge, between the speedo on the left and tacho on the right.

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All text copyright of Michael J. Bloxham.

If you would like to use any of these materials, contact me first at michaeljbloxham@yahoo.com

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