In 1985, the FISA (former ruling committee of the FIA) announced a possible replacement class to Group B that was referred to as “Group S”. The new regulations would require only 10 cars for homologation and was essentially a “prototype” class for rallying. The class was originally scheduled to make its debut on January 1st 1988, then as a heavily revised replacement to Group B for 1987, but both were ultimately cancelled. To learn much more about the history of Group S, please CLICK HERE!
THE DELTA S4 “EVOLUTION 2” / SE040 – Prologue
In early 1986, before Group B’s official ban, Abarth was already working diligently on a second evolution “E2” version of the Delta S4 (code-named project SE040) which would have brought further improvements to the rally car. The main goals were; better engine and gearbox reliability and performance, new front suspension design, better aerodynamic efficiency, and better handling specifically by shifting more weight towards the center of gravity.
To achieve this, new ideas were put forward towards the car’s aerodynamics. It would be improved with use of side skirts, (or “miniskirts”), fins added to the rear spoiler’s sides, and a rear extractor (diffuser). Furthermore, a flexible teflon flap fitted to the underneath of the front of the car would aerodynamically deform depending on vehicle speed and help with providing more downforce. The intercoolers (heat exchangers) were considered to be moved from the rear to a top mounted position (fed by a larger roof scoop), with the side air scoops (ears) now used only to achieve engine bay venting (which could allow them to be made smaller and more aerodynamic). Finally, the twin headlights setup would be replaced by a dual function single unit per side. All of these improvements were actually tested in FIAT’s wind tunnel between March and April 1986.
On the engine and drivetrain side, the twin-charged engine was meant to be improved with the possible use of a new toothed belt driven supercharger or the unit replaced altogether with a new sequential twin turbo setup made possible due to recent advances in electronic controls. These new electronics would also have permitted use of a new electronically controlled limited slip differentials. A F1-derived continued-variation “CVT” type transmission, developed by Dante Giacosa, was actually tested but was found to be inadequate due to the massive torque surges of the engine.
Sadly, the SE040 “E2” project was ultimately cancelled alongside Group B. However, for possible use in the Group S replacement formula, most of the SE040 technical advancements carried intact on to the new “SE041” project: the ECV (Experimental Composite Vehicle). The resulting car was displayed at the 1986 Bologna Motor Show:
ECV / SE041
The ECV had something entirely new to the Delta S4; an experimental chassis made out of a carbon fibre and aluminum honeycomb monocoque, which had actually previously been developed and produced as a design study in 1984. The new bodywork also incorporated carbon/kevlar, thermoplastics, and fiberglass body panels. Even the wheels were experimental Speedline composite units weighing only 6 kg (13 lbs) each. The chassis itself was claimed to be 20% lighter with equal torsonial stiffness than the standard steel space-frame unit of the Delta S4 and was one of the first to use computer assisted design in its conception. Such technology and materials were normally reserved for Formula 1. Engineers claimed that, if further the development of the chassis had continued, a theoretical target of 40% improvement in lightness would have been possible.
Another distinctive difference with the Delta S4 was the use of a “TriFlux” engine. While the basic 1759 cc engine block remained the same, the head was totally redesigned in conjunction with a new sequential twin turbo setup. The new design which had one exhaust and one inlet valve on each side of the cylinder head, with the resulting twin exhaust manifolds each feeding one turbocharger. At low engine speeds one turbocharger exhaust was shut-off, forcing all the exhaust gases through one unit and thus providing good low speed performance. As the engine speed rose, the second turbocharger was gradually introduced, until at high engine speeds both turbochargers ran in parallel. The more homogeneous heat dissipation means less chance of the head buckling under high loads as well as being far easier to cool through the standard liquid cooling system. The TriFlux was said to provide up to 600 HP with less turbo lag than the standard setup.
The aerodynamic features originally planned for the Delta S4 “E2” were implemented such as the single headlights, side skirts, rear diffuser, finned roof spoiler, smoother side scoops, and alongside a new front air dam. The intercoolers planned to be moved to the roof scoop were relocated in the side scoops instead. This new setup, paired with the new enclosed rear undercarriage, necessitated the rear screen to be replaced with louvers to aid in engine bay venting. However, this turned out to be less efficient at dissipating heat than the normal setup which was greatly aided by a natural low pressure zone under the rear edge of the car.
The ECV embodied the exact vision that the FISA had for the original draft of Group S back in 1985; new ground-breaking innovations in lightweight chassis design, exotic materials, aerodynamics, and advanced electronics. In theory, would Group B not have been banned, the ECV (minus its carbon tub) would most likely have first seen action as the Lancia Delta S4 E2 in 1987.
PROJECT SE042 / Group S Prototype
For the much stricter revised Group S rules set to replace Group B, Lancia actually abandoned the idea of using the ECV in favor of developing a smaller Delta S4 variant: project SE042. This new Group S rally car would be directly based on the Delta S4’s tubular chassis with mostly identical mechanical and transmission systems. The biggest change would come in the use of a smaller 1430 cc turbo engine to be included in the “up to 2000 cc” class and would have complied with the 300 HP limit set by the new regulations.
The new smaller engine, since it would have produced less heat, provided for unique opportunities to improve on the Delta S4; the front-mounted radiator could be made smaller, which in turn could be used to improve the car’s frontal aerodynamics, and allow room to fit dual shock absorbers. Use of a single (instead of two) top mounted air/air intercooler fed by the side scoops would have eliminated the need for the roof scoop, help make the car more compact, hence improving aerodynamics. No actual prototype has been built and the car only existed in theory since Group S was ultimately cancelled outright alongside Group B.
However, while the SE042 project was stillborn, Lancia did not stop the development of the ECV and would give Abarth the task to improve the design even further:
In 1988, as another design study, Lancia unveiled an even more radical version of the ECV; Simply dubbed the “ECV 2”, it featured the same carbon / aluminum monocoque chassis and TriFlux engine as the ECV, but it made way with the Delta S4 traditional appearance in favor of a better flowing aerodynamic design. The front and rear of the car were made as compact as the chassis and mechanical elements allowed, which also necessitated moving some of the engine’s ancillaries to the front of the car to improve weight distribution. The twin intercoolers had to be made smaller so they were moved lower for a better center of gravity. However, since airflow was limited the intercoolers now featured water cooling.
It is worth to mention that the ECV2 literally used the very same chassis and TriFlux engine as the ECV, which means that the latter was completely dismantled for the fabrication of the ECV2. As such, the original ECV does not exist any more. However, in 2010, Giuseppe Volta, with the help of many former Abarth team members, rebuilt a replica by using a standard tubular Delta S4 Stradale (road car) as its base and by using original ECV parts left over. To complete the work, a new TriFlux engine was painstakingly recreated with the help of the unit’s original designer: engineer Claudio Lombardi. The car was first publicly displayed at the 2010 Rally Legend event.
Both ECV cars were deemed as “impossible to drive” by Abarth’s test drivers due to the TriFlux’s very small torque figures at low RPMs and the huge blast of power when the turbos reached unison. To try and fix this problem on the ECV2, the turbos were reduced in size but with increased boost levels which resulted in slightly better drivability for the same amount of horsepower. However, all agree that the potential of the engine and the cars themselves would have been greater if enough development had been put in. Sadly, since Group S was annulled, this never happened. So, even though the ECV and ECV2 would never race, the exercise was a favorable showcase of technology for FIAT/Lancia/Abarth, pioneering many technologies 20 years before their actual debut in production cars, and providing an all important glimpse at the ultimate iteration of the Delta S4’s engineering.
It is worth to mention that the very last bit of engineering done to the Delta S4 platform was the testing of a four wheel steering system that was fitted on a Stradale (road car) version in 1988. At the end of these tests, the car was returned to factory form and sold, thus closing the final chapter of the Lancia Delta S4’s development.
ECV 1/2 SPECIFICATIONS
|Group/class||S – never raced|
|Type||Abarth 233 ATR 18S “TriFlux”, I-4, DOHC 16v, gas||located middle longitudinal|
|Capacity||1759 cc||WRC: x 1.4 = 2463 cc|
|Output power – torque||600 HP @ 8000 rpm||398 lb-ft @ 5000 rpm|
|Materials||block: aluminium alloy||cylinder head: aluminium alloy|
|Ignition||firing order 1-3-4-2|
|Lubrication system||dry sump|
|Type||four wheel drive||Hewland 5 speed gearbox with magnesium housing and straight cut gears (dogbox)|
|Differential ratio||N/A||central Ferguson FF epicyclic differential with 30% – 70% F/R distribution and automatic viscous coupling. Front: free. Rear: locked 25%|
|Clutch||dry – double plate|
|Type||Load-bearing structure made of carbon fibre & aluminum honeycomb with steel tube screen front structure. Bodywork mostly made of carbon and Kevlar resins, thermoplastics, and fiberglass.|
|Front suspension||double unequal wishbones, coil springs over Bilstein hydraulic shock absorbers, anti-roll bar|
|Rear suspension||double unequal wishbones, coil springs, twin Bilstein hydraulic shock absorbers, anti-roll bar|
|Steering system||rack and pinion||2.5 turns|
|Brakes||front and rear ventilated disks 300 mm diameter, 4 piston calipers all around||hydraulic pumps in parallel with manual balance adjustment|
|wheelbase: 2.440 m (96.1 in)||front track: 1.500 m (59.0 in)||rear track: 1.520 m (59.1 in)|
|Rims – tires||Composite Speedline Experimental
|Fuel tank||25 litres|
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