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This
article appeared in Mini-World November 1996.
Like
many of us, Nathan Dobson began his driving career in a standard
1000cc Mini (reg GLK 114T). He learned the basic driving skills,
passed his test and then used the vehicle as his regular daily driver.
However, as he was, at the time, an apprentice mechanic - he is
now a fully trained Rover technician - it wasn't long before he
developed a thirst for more power. But, unlike most of his peers,
he didn't want to splash out on a GTi or XR3 in order to fulfill
his heart's desire. Instead, Nathan decided to endow his standard
Mini with the power equivalent of those faster and more expensive
cars.
Nathan's
first foray into tuning involved fitting twin SUs and a loud exhaust
system. Unsurprisingly, this didn't satisfy him for long and soon
he took the next steps towards acquiring more grunt. Consequently,
a Mini Sport 1293cc short motor was located and then he fitted a
544 cam, modified his own cylinder head and dropped it all on to
an Allegro box.
The end result was a cheap, but effective jump in horsepower.
Before
too long, the fourth spec was launched on the unsuspecting residents
of New Malden, in Surrey. By now, it was pretty much the ultimate
A-series stuff: the short motor wore a 649 camshaft, a stage 4 cylinder
head, belt drive systems for camshaft and auxiliaries, a steel flywheel,
a straight-cut three-synchro gearbox and straight-cut drops. Realistically,
little else could be done, but he hankered after more!
Nathan's
father introduced him to Mark D'Souza and, between the pair of them,
a definitive master power plan was devised - there would be no need
for further mods after this! The plan was big: the A-series would
be replaced with a Vauxhall motor, but a 1300cc or 1600cc version
didn't feature in their designs. No, it was the two-litre, 16 valve
lump that formed the basis of the 1995 British Touring Car Championship
winning Cavalier or nothing!
During
the winter of 1995, work began in earnest. To the consternation
of some of his friends and colleagues, the Mini was pulled to bits,
and the 1300cc motor was sold. The funds that he raised from the
sale enabled him to buy a very good low-mileage Vauxhall lump, with
plenty of change left over. Finding the gearbox was simple: a £60
Mk1 Astra model from a breakers yard. So, total spend so far was
£760, with £240 left in hand. In its standard form the Vauxhall
engine produces 150 BHP, but Nathan decided that modifications were
necessary. The fuel injection system was removed and was replaced
by twin Weber 45 DCOEs. This raised the power to 180 BHP and simplified
the installation too.
Now
it was time to make the engine fit. Nathan and Mark put the Mini
to one side and obtained a donor front sub-frame and the front section
of a scrap shell. The plan was to install the engine in the sub-frame
and repeatedly lower the front bodywork over the top to check for
clearances and any necessary bodywork shaping. This meant any mistakes
could be corrected before starting work on the real thing.
The
location of the engine in the sub-frame was governed principally
by drive-shaft angles. It was necessary to situate the engine as
far back as possible: everything in front of the towers was cut
from the sub-frame. This meant that all of the suspension mounting
points were still retained, with the exception of the front tie-bar
mounting. The sub-frame was reconstructed in box tube around the
Vauxhall lump, and the original front lugs were incorporated, so
that the front suspension geometry and drive-shaft angles were unaltered
from that of Minis in general. Despite having the engine so far
back, everything was still tight at the front when they lowered
on the body section.
With
the gearbox on the end of, as opposed to underneath, the engine,
the cam sprockets and drive belts were located partly under the
front offside wing. In addition, the alternator was fixed extremely
tightly against the front panel, as were the centre two branches
of the exhaust manifold. As there was very little space here for
the radiator, it was decided that this should be relocated to the
boot. All in all, Nathan and Mark were concerned about the practicalities
of such a tight installation and worked on an alternative scheme.
The
front wing had to be lengthened by two inches and raised by three-quarters
of an inch. This was done to ease the clearances and enable a front
radiator to be installed; by raising the wings and front panel,
the bulge caused by the timing belt end of the engine could be reduced
drastically too.
Now
the engine mounts could be made: they used Cortina front and Fiesta
rear rubbers and fabricated sub-frame mountings were produced. However,
the drive-shafts proved to be a problem as GM patterns were required
at one end and Rover at the other. It is possible to have these
items individually made but the expense involved dissuaded them
from that idea. Instead, Jim Weston, a former wartime engineer and
Nathan's neighbour, stepped in to help. After calculating the necessary
length, both shafts were cut, turned to a point and arc-welded together.
Then it was smoothed and straightened.
Now
it was time for the next big step and, fortunately, after such thorough
preparation the cutting went smoothly. The front bodywork modifications
and a full repaint were undertaken by Paul of KRD Coachworks, and
the clean and distinctive results speak for themselves.
Jim
Weston made up some solid front sub-frame top mounts and pre-1976
front sub-frame rear legs were used to keep things steady. An air
box was let into the front bulkhead to accommodate the 45s, and,
by machining an angle onto the face of the inlet manifold, the carbs
were inclined sufficiently to allow proper air filters to be attached.
Finally
after nine months, the work was complete and the car was a runner
again - and it was impressive. So I was invited to try the Mini
in its urban environment on the Surrey streets. Initially, Nathan
drove and I nervously attached the full harness belts and settled
into the Corbeau bucket seat. Moving off in second gear, the car
sounded nothing like a Mini: the induction noise was all Weber,
but the drive was smooth. On to the open road, and in a burst of
second and third gears at full throttle, we were literally hurled
up the street. I was petrified!
In
the driver's seat, a sense of calm returned. The interior trim is
sparse as the car is intended to be used for drag racing too. Moving
off in first gear, it was obvious why Nathan always chooses second.
With the Mini only having 10" wheels and such immense torque, second
is only really first and a bit, so it's the best gear to use. The
car drives well at moderate speed; its 180 BHP has been developed
in such a way that the idle and low revs performance is super smooth,
as you would expect of a modern road monster. The brakes are adequate,
and the handling and ride is that of the standard car, but a simple
quirt of the throttle propelled us to another planet. There was
no delay or lag, just instant propulsion.
For
a road car, the grunt is beyond comparison, but the brakes simply
don't measure up; this must be the next area for modification. For
this job, vented Metro Turbo discs with Metro iron four-pot calipers
can be made to fit beneath a 10" wheel and sourced from a breakers
yard. By the same token, the handling cannot be expected to cope
with this sort of power. If pushed hard, the Mini will become
an over-steering monster. So more precise control of the front suspension
is needed; rose-joints are the best choice, but even up-rated bushes
would give some improvement. However, Nathan has already taken account
of this: on the list behind brakes, suspension and the set up generally,
is the exhaust system, a beam axle for the rear and an LSD to deal
with traction. The exhaust down pipe has to pass under the sump
as it gets damaged by even modest bumps. Nathan intends to solve
this by removing the sump, and creating a passage for the pipe between
the sump and clutch housing. The beam axle is intended to reduce
the weight further, and the diff is aimed at performance on the
drag strip.
When
the Mini was in its A-series spec, it recorded 16.2 seconds for
the standing quarter-mile with a terminal speed of 82 mph. Now complete
with its Vauxhall engine motivated and 13" slick shod that has been
reduced to 14.6 seconds at 26 mph. These are credit-worthy figures
and, with suspension and brakes to match, this Mini will be able
to compete with anything it meets on the road.
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Look very closely
at the front of Nathan Dobson's Mini - a slightly raised blimp in
the Cooper bonnet stripe indicates something a little out of the
ordinary.
The Vauxhall 2
litre lump in a round-nose Mini!
Sparse interior
for drag-strip work.
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