Vehicle Description
With an ever changing staff in Porsche's experimental department,
there was no shortage of fresh ideas, but at the expense of
continuity and experience. Much of the experimentation done in
Zuffenhausen concentrated on constructing racing cars, which not
only won many races, but also served as rolling test beds for new
developments. Under the guidance of Ferdinand Piech, Ferdinand
Porsche's young grandson, a dedicated racing department was set up
as part of the experimental department he headed. In his brief
stint at Porsche, Piech had already worked on the development of
the six cylinder engine of the 911 road car and the competition
904/6, before he officially took charge of the experimental
department early in 1966. In the preceding months he already made
his mark by developing the first of a line of highly successful
racing cars all designed along the same lines.
In 1965, the works were still developing new six and eight cylinder
version of the 904 GT racer. From the start the 904's design was
compromised for ease of construction as a run of at least 100 cars
were required for homologation purposes. The simple steel frame
chassis construction was very rigid, albeit a bit heavy. In its
first two seasons of racing this flaw was disguised by the car's
excellent road holding characteristics and powerful engines. By the
summer of 1965, Ferrari's radical and very light V6 engined Dino
racer had exposed the 904's weak point and had rendered it obsolete
on the spot in the European Hillclimb Championship. Piech's team
sacrificed the traditional August break to develop an instant
answer to the bright red mountain stormer. The 904's ladder frame
was discarded in favour of a lighter spaceframe construction that
had previously been used for many of the successful road racers. To
lower the car, 13 inch wheels were planned to be fitted, but
Porsche had no wheels of this diameter or suitable uprights
available. In a unique deal the required bits were purchased from
Lotus who used a similar setup for their Formula 1 racers and were
than happy to ditch some of the spare parts after the German Grand
Prix. Fitted with a lightweight spider body and a flat eight Grand
Prix engine, the new racer made its debut at the end of the month
in the Swiss Ollon-Villars hillclimb. Simply known as the
Ollon-Villars Spyder, it showed its lack of development and
testing, and Ferrari again took the better of the Germans.
Although the European Hillclimb Championship was a popular past
time for the continent's racing car manufacturers it was not the
top priority. The Ollon-Villars Spyder was not a winner out of the
box, but did show great potential and its design would form the
basis for the 904 replacement. All work on the larger engined
versions was dropped in favour of the new spaceframe car. The
sport's governing body, the FIA, had brought the homologation
requirements down from 100 to 50 for Group 4 GT racers. The
spaceframe chassis was still too complex for Porsche to construct
in such a short time, but this was overcome by outsourcing the work
to Karosseriewerk Weinsberg. Much of the development work
concentrated on getting the light chassis up to the rigidity levels
of the 904's. Once that was achieved a lot of time was saved by
fitting the front and rear suspension that had contributed much to
the old car's success. Many of the parts had already been ordered
for the cancelled second 904 production run. The remaining time was
spent on tuning and lightening the six cylinder engine found in the
904/6. In production form the new flat six already used lightweight
materials like aluminium, but for the competition version Piech's
team replaced the aluminium parts with magnesium and the steel bits
with titanium. Magnesium was already used in the flat-eight Formula
1 project, but the use of titanium was previously restricted to
space-ships only. The end result of the extensive diet was an
engine that was lighter than the 904's four, yet still durable
enough to survive endurance racing. Officially the engines produced
210 bhp, but a figure of 220 bhp was closer to the truth. This was
almost twice the amount available in the similarly engined 911 road
car. The very efficient shape was the result of 'Butsy' Porsche's
intuition, but for the new racer the team relied on the windtunnel.
The resulting fiberglass body was slightly lower and considerably
wider that its predecessor's. Despite the increased frontal area,
the drag was only slightly increased and the long nose provided for
more downforce at high speeds.
The six cylinder engined 904/6 model received chassis numbers
starting with '906' to distinguish them from the previous version.
The 906 name was never publicly used so it was adopted by the
factory as the cars official name. Not only did it follow the
traditional naming policy, the last digit was also a true
indication of the engine fitted. The PR department continued
another tradition by referring to it as the 'Carrera 6', much like
the 904 had been known as the 'Carrera 4'. Within a month after the
first example of the 906 was completed, it made its competition
debut in the January 1966 Daytona 24 Hours. Compared to the local
racers, the tiny size of the navy blue Porsche became apparent.
With a sixth place finish and a class victory, Porsche's latest
racer immediately showcased its potential. Within a few weeks of
the announcement of the new car, all 50 were spoken for. Before the
car could be fully homologated the completed examples were forced
to race in the prototype class where it again faced the similarly
petit Ferraris. The Italians never planned to homologate the car
and only one or two were usually present at any race and they
quickly faced an armada of Porsche's latest. The two six cylinder
racers were equally quick, but the quantity and durability of the
906 usually gave it an edge over the Dino. By the end of April the
required 50 cars were completed and from May 1st it was homologated
as a Group 4 GT. This was celebrated a week later in the Targa
Florio where the 906 scored an overall victory. Porsche could
comfortably leave the privateers to defend their honours on the
track where it easily outran the competition. Not only did the new
racer perform great on the track, it was also well received by the
motoring press who quickly nick-named it 'Batmobile' because of its
gullwing doors.
Back in Zuffenhausen no time was wasted and immediately after the
fiftieth car was completed, work was already started on
improvements. Throughout the racing world the fueling system old,
Carburetors, was replaced with Fuel Injection. In the preceding ten
years much experimentation was done with injection, but it was not
until the second half of the 1960s that a setup was developed that
was really superior to the good old 'carbs'. For the 906 engine
Porsche turned to fellow German's Bosch to replace the Webers with
a state of the art system. Equipped with the Bosch injection the
engine's performance did not increase, but it was much easier to
fine-tune and offered better throttle response. Together with the
new engine, a slightly revised bodywork was introduced, which
brought drag levels back to the 904's figures without sacrificing
any downforce. The evolution was dubbed 906E for Einspritzung, or
injection, and was forced to run in the prototype class. One of the
first outings for the injected 906 was the 1966 24 Hours of Le Mans
race where they filled places four to six behind three Ford GTs. It
also secured a top spot in the Index of Performance. A second
evolution was the installation of the advanced eight cylinder
engines in the chassis with hopes of creating an overall winner at
the twistiest of tracks like the Targa Florio and the ...for more
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