Fué la sustitución del 037, y uno de los más emblemáticos modelos del WRC. Tuvo infinidad de evoluciones, respecto al 037, convirtiendolo en el rival a batir. Desgraciadamente fue a bordo de un Delta S4 donde murio H. Toivonen y su copiloto.
Era una auténtica máquina de correr, tenía toda la sabiduría y experiencia de Lancia, de tuvo que luego adaptar e ir suministrando poco a poco al Delta Integrale Gr. A (Deltona), hasta su desaparición como marca participante en el
Advanced planning of the DELTA S4 began in January 1983 with the production of 1:5 scale drawings. At that time no official decision about construction had been made, however on the basis of that initial study, senior Fiat management soon gave the project the green light. Full engineering planning began in April 1983.
Delta S4 - Group B Rally CarBy 1985 Lancia had produced the phenomenal Delta S4. In reality it was a completely new chapter in the family of four-wheel drive Deltas. The car was expressly designed for Group B rallying, and as such only 200 cars were constructed (for homologation purposes).
The S4 engine was the first rally unit to be built with electronic ignition and fuel injection, and even more important it was the first completely new engine to be specifically designed for this type of work. The engine was also the first to be constructed by the Fiat Group with an all new light-aluminium cylinder block and base. The aluminium cylinder barrels were set into the block and surface hardened by a special ceramic process.
Delta S4 - Group B Rally CarThe most amazing innovation was the adoption (for the first time in the world) of a simultaneous duel supercharging system, comprising both volumetric and turbo compressors. Structurally the S4 uses a tubular space-frame chassis in chrome-molybdenum steel; all round independent suspension with unequal-length arms; permanent four-wheel drive with central torque splitter and limited-slip viscous coupling; self-locking ZF differentials front and rear; brakes with ventilated Brembo discs, and rack and pinion power-assisted steering.
The 1759cc four in-line engine was longitudinally mounted, with four valves per cylinder, integrated I.A.W. Weber Marelli electronic fuel injection/ignition. It had electronically managed supercharging by a Volumex compressor and a KKK turbo. Two inter-coolers completed the system to lower the intake temperature.
A compression ratio of 7:1 with maximum power of over 400 HP at 8000 rpm and maximum torque values reaching 40 kgm at 5000 rpm, produced a top speed of 208 kmph, with acceleration from 0-100 kmph in 7.8 seconds!
Delta S4 - Group B Rally Car
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. In a set of tests carried out in early November, Lombardi stated that the S4 had been timed at 2.8 sec from zero to 100 kmph and other figures showed that the car accelerated as quickly as a Cosworth engined Formula One car up to 400 metres, despite the rally car weighing 990 kgs.
Lubrication
All Gammas need a good quality oil and it is recommended that synthetic oil is used. However, after a full engine rebuild, with new bearings etc, regular high grade mineral oil should be used in the engine for the first 1000 kms, and then changed to synthetic.
Most engine parts do not wear prematurely, but one exception is the camshaft lobes. When the engine is stationary, oil will drain from the camshaft into the sump, and there is a delay when re-starting the engine before lubrication returns. Synthetic oil has a greater film strength, but it should be changed every 10,000 kms.
A full oil change, including the filter, will need 6/1 litres of oil. It is preferable to use the dip stick rather than rely upon the dashboard gauge to check the level. After changing the oil it is a good idea to build up a little oil pressure by turning the engine over on the starter with the low tension lead to the coil pulled off (the lower one on the coil), as this fills the new oil filter, and saves a few microns wear from your camshaft lobes.
Cooling System
Another common Gamma ailment lies in the cooling system, as overheating and head gasket failures can recur frequently. The use of caste iron liners with an alloy block is not uncommon, but in the case of the Gamma, the liners tend to 'sink' into the alloy of the block causing gasket failure. This can occur not only at the head/block joint but also at the paper gasket joint at the base of the cylinder liners, allowing water into the sump. The usual signs are loss of water, often gradual at first, and a milky residue on the oil filler cap, and the oil in the sump looking like chocolate milkshake.
The Gamma takes 9 litres of coolant and it should be mixed 50/50, water/antifreeze. A good quality antifreeze containing corrosion inhibitors should be used. Remember before flushing and refilling to put the heater on beforehand with the engine running (to allow the vacuum-servo controls to work). After refilling, run the engine and top-up the expansion bottle as necessary as air is expelled from the system.
Note that all Gammas should have a T-Piece connector at the top of the radiator with small diameter hoses going to the top of the inlet manifold and to the expansion bottle, to allow air to escape. This was not fitted to early cars and air within the radiator became trapped. Blockages in the small diameter hoses can cause the same problem, leading to a build up of vapour in the system.
Also check the condition of the water pump, as these have a lire of around 10-12 years. Parts are available to overhaul these pumps. although they are difficult to get apart and take time and patience.
Ignition
The ignition timing should be 29 deg BTDC at 3000 rpm and 31 deg BTDC at 4500 rpm with the vacuum hose disconnected. The timing marks are stamped on the flywheel teeth and are visible (just) from the nearside of the car through a small aperture in the bell housing.
Spark Plugs : NGK BPR6ES
Bosch WDSC
Champion N6YC
Correct gap width is 0.6-0.7mm
The Bosch distributor and electronic ignition rarely give trouble, but rotor arms sometimes breakdown. Plug leads should be the original if possible, but if they have to be changed don't use heavily suppressed leads as this is measured as resistance per metre length.
Salu2
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