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Lancia Delta S4
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1985 |
Country: |
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Engine: |
4 cyl. Turbo/Supercharger |
Capacity: |
1759 cc |
Power: |
250 bhp |
Transmission: |
5 spd. man |
Top Speed: |
140 mph |
Number Built: |
200 |
Collectability: |
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Being one of the most high-tech cars ever built,
the Lancia Delta S4 had a legendary and dramatic fate.
It had actually no relationship with the production
Delta series (the most noteable difference being the
mid-engined design and tubular space frame chassis).
Designed for racing from day one, the Lancia clearly
had the Peugeot 205T16 and Audi Quattro Sport in Group
B world rally championship in its sights.
Lancia's Monte Carlo rally car was, by 1985, seriously
outgunned in performance by the Pug and Audi, giving
up some 60 bhp to its rivals.
Compounding the performance
issues was the fact that the Lancia was a 2WD competing
against 4WD rivals.
While the Delta S4 was styled and named to promote the
mass-production Delta, it was in actually a clean sheet
design.
Adopting the more popular mid-engined layout,
the S4 engine was longitudinally mounted behind the
front seats, directly driving the viscous-coupling LSD
which transfered 30% torque to front wheels and 70%
to the rear.
At each of the corners of the steel tubular space frame
chassis, the suspension used double wishbones with twin
absorbers. The body was a composite glass-fibre/epoxy
resin.
While its 4WD system was not as advanced as the Peugeot
205T16's (which had variable torque split between front
and rear axles), its engine far more advanced, employing
tboth a turbocharger and supercharger simultaneously.
A turbocharger is generally regarded as the most efficient
means of forced induction, but it requires higher revs
(hence a lot of exhaust gas) to operate. The result
is poor low-speed power and the presense of turbo lag.
A supercharger performs strongly and instantly right
from idle, but it is rahter inefficient at high rpm.
For a rally car, a flat torque curve over a wide range
of rpm is always crucial - and that is why Lancia spent
a lot money with Abarth to develop a system combining
both turbocharger and supercharger.
The S4 employed twin intercoolers, one for the turbo
and one for the supercharger. The supercharger worked
at low speed, and when the turbo cut in, a bypass valve
relieved the pressure from the supercharger so that
energy efficiency was lifted. The result of the combined turbocharger and supercharger
meant that the 1.8-liter engine produced a mind blowing
250 bhp and a healthy 214 lbft of torque, while the
rally car upped that to 470bhp and 333 lbft.
Like other Group B cars, only 200 units of road version
were made to fulfill the minimum requirement for homologation.
In WRC, the Delta S4 experienced a dramatic fate. It
won its debut race, then continued to dominate the following
races and was leading both the driver and manufacturer
championship standings. Such excellent results amazed
everyone, since it was a completely new car.
Sadly, during the 1986 Tour de Corse (Corsica Rally),
driver Henri Toivonen and navigator Sergio Cresto (who
were leading the race) crashed in their S4 and both
were killed. The team lost its momentum and eventually handed the
title to Peugeot. This accident led to the rethink of
Group B cars. Races went on but finally FIA annouced
the termination of Group B, because it was too powerful
and dangerous. Therefore, Delta S4 became the most outstanding
rally car in history not to win a world title. |