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December 18, 1957 THE
MOTOR
THE
LOTUS XI LeMans "85"
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A Two-seater with Racing Performance which can be Run on the Road |
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RECORDING
a maximum speed of 125 m.p.h., as an average of timed two-way runs with a
passenger as well as a driver being carried, the Lotus XI provides a vivid
illustration of the huge gain in small sports car performance which has
taken place during the past decade.
Able to accelerate the same two-man load from a standstill to 100
m.p.h. in only 23.6 seconds, this car invites incredulity as to its modest
1,096 c.c. engine size, until almost equally miraculous fuel economy
figures (which range from 32 1/2 m.p.g. at a sustained 100 m.p.h. to 55
1/2 m.p.g. at a steady 40 m.p.h. on the level) are also observed. What
sort of a car is it that Colin Chapman’s brilliant team of young
engineers and aerodynamicists has endowed with such astonishing
acceleration, speed and economy of fuel? It is, in the form in which we
drove it, a somewhat Spartan car in many respects, built to have Spartan though it is by conventional standards, however, the Lotus XI with its background of success in long-distance races comes to be appreciated after a little while as an oddly comfortable car. Suitably clad and shod, a driver settles down to become very much at home behind the leather-covered steering wheel, with all the controls very conveniently at hand, and comfortably supported by the bucket seat, the curved rear wheel arch which forms a shoulder-rest on the right, and the high transmission tunnel which serves as an armrest on the left. Waste space around the passenger is even more scarce than around the driver, because of the handbrake, an unsymmetrical gearbox cover, some lateral frame tubes, and on the test car some all-too-accessible mountings of the electrical fuse and regulator boxes: yet a passenger also can learn to settle down and really enjoy being motored around with astonishing rapidity. Luggage space is scanty, there being room for a parcel above the enclosed spare wheel and for two more thin parcels just inside the doors, but as tested this was a car to carry its driver and either a passenger or some luggage, fast enough to win awards in racing yet able to run on the public roads without exciting the disapproval of the law. Available variations on the basic body include on the one hand a single-seat windscreen giving extra top speed, and on the other hand a glass windscreen giving two people slightly greater protection from the elements. For
experts on ordinary touring cars to assess the merits of the Lotus Xl as a
racing machine would be a foolish impertinence, and is unnecessary since
results already achieved speak for themselves. Victories all over Europe
and in America have confirmed that the speed and handling qualities of
this model match one another. During 1957, a wishbone type of l.F.S.
replaced the divided-axle layout used on earlier Lotus cars, and the
result has been a great gain in ease of control at three-figure speeds on
imperfect surfaces by drivers of no more than normal competence, without
any offsetting loss of ultimate cornering power being evident. Several
engines can be used in this Lotus. from the 40 b.h.p. Ford 1,172 c.c.
side-valve through 1,098 cc. overhead- camshaft Coventry Climax engines in
75 b.h.p. and 84 b.h.p. forms to single-camshaft and twin-camshaft 1
1/2-litre units of limited availability developing up to 145b.h.p.
Our test car had the 1,098 c.c. Coventry Climax engine in stage 2
tune, developing 84 b.h.p. at 6,800 r.p.m. but giving less torque below
4,000 r.p.m. than does the 75 b.h.p. stage 1 engine. Wheel adhesion was
improved because a ZF spin-limiting differential supplemented the deDion
rear axle layout on the test model, but this individual car's racing
history penalized it to the extent of a 20-gallon petrol tank and
extra-heavy gearbox as weight-increasing relics of past service with a 1
1/2-litre engine and in long-distance races. With
only slight silencing of the exhaust and a fair amount of mechanical
clatter, the stage 2 engine does not invite hard driving around towns.
Numerous journeys in and out of central London at busy times showed a
tendency for the coolant to heat up somewhat in traffic jams, and a firm
clutch combined with splined rear wheel drive shafts, invited juddery
starts from rest, but despite ragged carburation at low r.p.m. there was
no plug-oiling or other serious temperament. Even when driven hard, the
engine used very little oil. In the absence of choke controls, winter
starting from cold required two hands to cover the carburetor intakes
while the starter was operated, but the engine soon warmed up enough to
pull normally. In
rural surroundings, the stage 2 engine begins to awaken at 3,000 r.p.m., develops its best torque
at 5,000 r.p.m., and is still pulling very vigorously indeed at the
suggested limit of 7,500 r.p.m. beyond which a risk of harmful contact
between valves and pistons soon arises. The cry of a Lotus being driven at
high r.p.m. and a wide throttle opening is decidedly audible, but less
anti-social than it might be because a Lotus driven in this fashion
disappears over the horizon and out of earshot in a brief space of time. Eight
different rear axle ratios are available for the car, covering a range
from 3.73/1 to 5.375/1, and our test was made with a 4.22/1 ratio with
which almost exactly the maximum permitted r.p.m. were indicated at the
timed maximum speed of 125 m.p.h. with full-width windscreen. For our
usual standing-start acceleration tests with two people in the car, this
axle ratio was too high to give best results, engagement of the clutch at
even 5,000 r.p.m. being followed by a drop in r.p.m. to a figure at which
there was momentary hesitation, and no wheel- spin or clutchslip being
evident. But, if a rest-to-30 mph. time of 4.6 seconds and a standing
1/4-mile time of 17.3 seconds do not represent the best that a Lotus can
achieve in two-up trim (without a l 1/2-cwt. passenger, this 9 3/4-cwt. car
becomes substantially livelier) such figures as rest-to-60 m.p.h. in 10.0
seconds and rest-to-100 mph. in 23.6 seconds are remarkable for a car of
any size and would until recently have seemed wildly impossible for an
un-supercharged 1,100 c.c. car carrying two people and using pump petrol.
Most people will find that, in the lower gears, they have more power than
they know how to use from this 1,100 c.c. Lotus, but once familiarity with
the car is acquired the average speeds put up on away-from-towns
cross-country running are astonishing, a reminder that the congested state
of popular routes on summer week-ends has not eliminated all opportunities
to go motoring for fun. Perhaps
partly because the coil springs had settled slightly (Lotus road-holding
is based upon flexible springs controlled by exceptionally firm damper
settings) the ground clearance of our test model was quite inconveniently
small, especially below the disc-type inboard rear brakes but also below
the sump and elsewhere, so that moderately rough going or the landing on a
normal smooth road after crossing a hump-back bridge at just below
take-off speed would produce grating sounds from beneath the car. On rough
going, there was a considerable amount of rattle from the doors,
wrap-around screen section and elsewhere, the light-alloy body being
functionally simple and without a scrap of superfluous weight, but
ignoring this sound effect the riding comfort over most surfaces was good.
The Lotus does, however, show up to best advantage (in both riding
and handling qualities) on reasonably smooth roads. Built
so low to the ground and designed for racing, the car naturally corners
without any perceptible roll or sidesway. The rack-and-pinion steering has
comfortable self-centring action, yet is so precise and light that in
ordinary road driving up to and beyond 100 mph.. it suffices to hold the
wheel rim between the thumb and forefinger of one hand. Whereas earlier
designs of Lotus chassis cornered well but needed handling with a very
delicate touch order to run truly straight at speed, this model can be
placed precisely without conscious effort by the driver at speeds up to
more than two miles a minute. Not pretending to be racing drivers, we
confined our explorations of the ultimate limits of cornering speed to
occasions when there was spare room for any resultant excitements, and
whilst clumsy use of the power in a low gear on a very sharp corner could
flick the tail outwards quite quickly, the Whilst
a car weighing under 10 cwt. as it stands at the kerb does not demand
great retarding forces from its braking system, a top speed of 125 m.p.h,,
and wind resistance so low as to let the car run very freely on the
over-run, make good brakes extremely important on a car such as this. We
did not have a chance to sample this Lotus in the wet, but past experience
suggests that the Girling disc brakes would have been as reassuringly
adequate in wet weather as they were on dry roads during this test. The
pedal pressure needed actually to lock all four wheels is fairly high
(there is no servo assistance) but the proportionality of braking response
and the sustained firm feel of the pedal in repeated stops from high
speeds give a driver great confidence. The handbrake It
is not to be expected that the Lotus Xl will be bought as an economy car,
but the astonishing mpg. figures which it can record are a testimony to
its low air resistance and high engine efficiency. At any speed likely to
be used outside towns, over the range from 50 m.p.h. to over 100 mph.. it
would be difficult to find another car able to show equal economy of
premium-grade petrol. Built
for the extremely specialized purpose of winning sports-car races, for
which present-day requirements of roominess and weather protection are not
very onerous, the Lotus XI Le Mans does not represent the average
motorist's idea of an everyday car. But, it is a car which can provide
extremely fast day or night travel on ordinary out-of-town roads, and can
at the same time give immense enjoyment to suitably minded drivers and
passengers. As an engineering tour-de-force, this race-proved two-seater
of such astonishing speed and roadworthiness certainly suggests that the
forthcoming coupé model from the same designers is likely to be worth
waiting for. Click here for the test results table.
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