This is # 4 in the top ten Performance Saloon cars of the 1963 – 1973 era. The Cooper S range of Minis opened a new world of performance for small saloon cars and set in motion a track and rally heritage shattering previous convention.



PDM Clark - Mini Cooper S

ALEC ISSIGONIS the brilliant designer of the Mini could never have imagined the impact his creation would have on the world. This was not only something that up-ended the motoring environment from a tech perspective but the tumultuous years of the 60’s provided the Mini with a springboard to what a post war icon was all about.  As had become the norm, small cars were transport for the masses… and ‘little cars’ were but an interesting footnote… until the arrival of the Fiat 500 that is…a car that brought a good level of practicality in such a tiny package. In a way it could be said that the Mini became a reality in good part as a result of the Fiat, not because there was necessarily a logical business imperative to do so but largely because the BMC (British Motor Corp) chairman Leonard Lord  “disliked those horrid things” amongst other bubble cars around at the time…. and directed Issigonis to do a better job of a little car. Lord went so far as to give Issigonis the physical measurements (Length/Width) of the package to be penned.




That is very simply how the ADO 15 (Austin Drawing Office # 15) project commenced…and about 2 years later, there arrived a unique package… a very ‘big’… little car. The original Mini as we know it today.

Cross sectioned side view - PDM CLark


We could go off at a tangent and try to cover the complete history of this machine which would take multiple volumes but amongst this mass of info there were many things brewing which were destined to result in the S range of Mini Coopers…. There are two aspects we will look at, firstly we have to take a peek at what was happening in the UK towards the end of the 50’s and what lead to the creation of the Cooper S. Next, we look at the competition prowess of the cars in both racing and rallying.

Mini Smoking the outer wheel


Monte Minis



Issigonis was every bit a smart engineer… but like most at the time, functioned in an understandable 50’s mindset. He had set himself the task of producing a spacious (relatively speaking of course) inexpensive small car for the masses. He lived and breathed that philosophy and the original 850 Austin ‘Seven’ / Morris ‘Mini Minor’ looked to fit that role perfectly. Once launched to a largely unsuspecting public however, he soon found that market forces were to drive the little car in directions never before imagined.… This machine was going to write it’s own history…and do so with the help of another player writing an equally unique biography.

The early 60’s was a molten lava of tech folk getting into the world of modifying saloon cars and with BMC holding almost 50% of the UK market there was huge activity around the product.  More significantly, by the time the Mini was launched in 1959, 1.7 million cars were powered by that other player mentioned earlier… the somewhat archaic four cylinder BMC ‘A’ series engine…the machine that now powered the Mini.

A Engines BMC products


Riding this wave, the sheer volume and availability of this powerplant drove the tuning environment and as a natural spin-off, Morris Engines, under Eddie Maher developed the ‘XSP’…the officially sanctioned racing version of the ‘A’. Starting in 1958 and designed originally for longitudinal installations in Formula Junior, F2 and later F3 in open wheeler racing, these engines were also used in racing Austin Healey Sprites.

1961-Cooper T56 - PDM CLark


The point I make is that with both the aftermarket busy and BMC themselves involved in the quick engine business, the natural marriage of tuned “A” engines and the Mini happened as soon as the little car hit the ground. Involvement by the active BMC competitions department was significant and the Mini in racing and rallying mushroomed. The ‘go kart’ like feel and handling of the car along with those readily available quick engines were exactly what the doctor ordered.

We return to 1959 and the activities happening in Downton, Wiltshire. The small tuning firm of Downton  Engineering who, during the late 50’s had been upgrading a wide range of engines in the rapidly growing business of modifying cars, had decided to shift their tuning speciality to BMC ‘A’ engines exclusively. This decision was not directly related to the launch of the Mini but…as we were to see soon, the timing was perfect. Daniel Richmond the owner (& gifted engineer) had become one of leading tuners of A engines in the country… Downton Engineering turned their attention to the Mini immediately.

Downton Engineering - Mini Cooper | PDM Clark

THE EARLY 60’s DOWNTON OPERATION…somewhere in that lot are two names we were to later
acknowledge as leaders in tuning in their own right…Jan Oder of Janspeed and Richard Longman.

Downton Rocker Cover


At exactly the same time, John Cooper, already experienced in using the XSP BMC ‘A’ engines in his Formula Junior Coopers had spotted the potential of the Mini as a performance/race car and had bolted a derivative of an XSP into a Mini. He approached BMC to build his creation as a performance model…something Issigonis was not too happy about…

At this stage, these three participants Issigonis, Richmond and Cooper (unknown to one another at a business level at that point) were not to know that their collaboration was going to create one of the more significant performance cars of our time. Cooper remained pretty persistent about his quick Mini and essentially bypassed Issigonis, with eventual approval given by George Harriman, then the new BMC Chairman… so the first production  Mini Cooper happened in 1961, albeit in very moderate 997 twin carburettor form. This was a really significant event, being the first use of an established racing car brand linked directly to a performance saloon car in the UK…. beating Lotus to the punch with the Cortina by two years.

Downton Engineering, not missing a trick, purchased one and set about waving their magic wand over the little car.

Mini Cooper Mk 12

The First Mini Cooper… apart from badging and two tone
Paint virtually identical to a stock Mini.

What happened next is my assessment of the more significant events that resulted in the creation of the ‘S’ range of Minis.  Amongst much activity in the aftermarket, Richmond had been hard at work and made a modified 1098cc version of his Cooper available to Autocar.  Links between the Editor and BMC resulted in a telling telephone call to Issigonis (who by this time had warmed to the basic idea of a quick Mini) being told that Autocar had just tested a perfectly driveable ‘100 mph plus’ Mini…

The mindset of having a 100mph saloon car outside of a Jag at the time was exceptional stuff … that it was a Mini can only be described in more modern parlance as a bit of a ‘star wars’ moment. The Autocar event was not only a surprise to folk in general but highlighted the fact that within less than two years, the market was now dictating that unexpected direction for the little car … and, significantly, got the attention of Issigonis good and proper.

1961 became the watershed year…. Firstly the 997cc Mini Cooper had been launched as a production model… next, that first road test of a ‘Ton Up’ Downton Mini… and to top the year off, the first shot across the bows of established tin top racers…Sir John Whitmore won the British Saloon Car Championship in a Don Moore prepared 850cc Mini.


And so it soon became a three cornered effort with both John Cooper and Downton Engineering (Richmond) directly involved as consultants to the Morris Engine team and Competitions divisions. Somewhere else in my writings I have touched on the occasional rocky relationships which existed between the outside boffins (or as some engineer types refer to them as ‘hot rodders’) and motor company tech folk in these early days. This is one of the first the ‘modern’ era in the UK and BMC navigated these unchartered waters surprisingly well…

Things were heating up in 1962 and pressure from motorsport activities around the Mini in both racing and rallying were highlighting the potential… but also the weaknesses in design associated with top level competition. John Love was leading the UK Saloon car Championship driving a 997 Mini Cooper that year (he eventually won the title) and the Mini had bagged a good few rally wins as well. In the process it became abundantly clear that the long stroke 997cc engine, fragile in tough environments, now needed an upgrade to withstand the rigours of the competition to which the car was being exposed. The A engine needed some upgrading in the Mini application.

I will at this point deviate from the basic story and become a bit of a propellerhead. For those not aware of the cost pressures in car engineering environments, I can tell you that cost escalations are the enemy of the state. To justify increases as a result of design changes requires serious motivation and these are generally driven by the need to resolve field tech concerns or gaining market advantage by introducing new tech innovation. Traditionally the latter is done on as wide a range of product possible so as to amortise the investment. The S range of engines duly developed were neither, the mods were substantial, very costly, used on a very small % of vehicles and apart from the FIA homologation, required to achieve only two goals. Firstly, to allow the engines to produce as much power in competition form as could be achieved from the basic configuration and secondly, to prevent the A engine from showering the scenery with shrapnel…in a word be ‘unbreakable’. BMC were clearly serious about involving the Mini in motor sport….

History will show that this singular event was to change the fortunes of the little car forever. The above two objectives were more that met. In hindsight, given the very basic design of the original engine and the work that has been done over the years by the ‘A’ engine tuning fraternity, these upgrades were to result in the most effective production-based engine development during the period. Here I include the other two fabulous efforts in my top three…the Ford Kent/Lotus/Cosworth and the Chevy Small block.

For those that would disagree and put the Cosworth development of the Ford Kent ahead of the “A” transformation, I would just point out that whilst on a pure tech level the Cossie developments were far and away more sophisticated and ground-breaking…the “S” engine work was, to put it simply, far more effective in  getting competitive cars to tracks and rallies in huge numbers. The significant issue being that the performance and durability gains were made without changing the basic architecture of the engine.

Mini Collage


There was another serendipitous happening in 1961 and that was the arrival of Stuart Turner as the BMC Competitions manager. This was the man who would become one of the most respected in this field and who, after the heyday of BMC in motor sport in the 60’s, joined Ford to create the legacy of Escort dominance in Rallying during the early 70’s. We cover this to a good degree in Part two

My earlier comment will be understood well by those who have been in the engineering melting pot… because engineers can be a difficult lot and do not readily share responsibilities with peers. To do so with relative ‘unknowns’ was a landmark event. Yet very soon we had Richmond doing the cylinder head optimisations for the revised 998cc Cooper and the S range…. John Cooper providing support and direction in addition to the Cooper branding…. the BMC engineers (Maher) upgrading the A engine mechanicals and Turner rejuvenating the motorsport division.

All this activity resulted in the improved mechanicals being installed in a new range of performance Minis. The Cooper S hit the floor in 1963, the start of our ten year window and did so with the 1071cc engine first. The 1275cc version followed and finally the most interesting power unit being the 970 ‘S’ …all of which were produced to achieve the required homologation requirements for competition.


In previous posts I covered much of the story around the BMC A engine and the fact that I have never been a fan. The machine has all the hallmarks of a ‘clunker’…the basic specification littered with design issues that would, in a sane world, drive an otherwise experienced tuner to drink.* In fact when the first of these engines arrived in the Downton workshops in the 50’s, Bunty Whitaker (Daniel Richmond’s long-time partner, common law wife and fearsome workshop manager) instructed the technician concerned to remove ‘that piece of rubbish’ from her workshop and finish the repair under a tree in the yard….My thoughts were pretty similar when first laying eyes on this lump of cast iron…along with a lingering memory having to do with suitability as boat anchors…

*The ‘A’ engine in its basic arrangement relies on a Five Port cylinder head with inlet ports siamesed, one port each feeding Cyls 1&2 and 3&4 respectively. In addition, the centre cylinders 2&3 share a common exhaust port. The basic design is a long stroke with relatively small bores limiting valve sizes and relying on long pushrods for valve actuation. Due to port and camshaft location, Inlet Port size and shape are affected as a result of pushrod positioning. No rational engine tuner seeing this specification for the first time would have given a thought to the engine eventually becoming a force in motor sport.  


My view of the design has not changed…however… respect and admiration for those involved in the magical transformation of this machine is unbounded and testimony to the ingenuity and determination of the engineers and tuners involved.

The work done on the ‘S’ engines is almost matter-of-factly covered in the written works of the time and I get the feeling that much of the significance has been lost. Work completed on the XSP competition engines involving modifications to rotating components and cylinder block strength were transferred to the new road going ‘homologation spec’ S range along with the addition of changes to bore spacing.

Below is a list of the major changes made.

Typical 997, 998,1098 Bore spacing & S engine Bore spacing

  1. Engine Bore size enlarged to 70.63mm from the previous maximum of 64.58. This required the S engines to have ‘even’ bore spacing, moving away from paired bores and the gap between cylinders 2 and 3 on 997, 998 and 1098cc engines.
  2. The 970/1071 and 1275 ‘S’ versions had dedicated engine blocks, strengthened to improve rigidity, particularly around the centre main bearing as well as the removal of lifter side covers.
  3. Cylinder head sealing and rigidity was improved with the addition of an extra cylinder head fastener (a bolt and stud) at each end of the head.
  4. XSP knowhow resulted in crankshafts manufactured from EN 40 B steel & nitrided.
  5. XSP based connecting rods EN24V steel & stress relieved.
  6. Larger inlet and exhaust valves made possible through the larger bore area with the Exh valves manufactured from a Nimonic steel similar to the material used in jet engine turbine blades.
  7. The Downton Cylinder head port and combustion chamber designs incorporated into production engines.

I give the detail not only to illustrate the sophisticated materials used in order to ‘Bulletproof’ the engine, but to highlight the inclusion of outside engineer knowhow. These engineers were serious, damned good at what they were doing and again this was 1962…ground-breaking work for the period.

For a moment we need to digress and cover an aspect of the original Mini that is as much part of the character of the car as is the uniqueness of the package…the “torquey” engine response. My first ever experience of a ‘hot’ Mini was a visit to a Mini convert in around 1969. Barry still faithfully races Minis today in Port Elizabeth but this was his first venture into the realm of ‘Modded Minis’ and I had paid a visit to his home in Target Kloof. The car was typical of our machines of the day, all engine and not much else. A run in the car, with Barry driving, proved to be intoxicating. How I remember this I do not know but the engine was a 1098 (the ‘A’ engine with the longest stroke of all at nearly 84mm) fitted with the good hardware of the day, a ‘731’ cam, modded cylinder head and the Weber sidedraught ram tubes poking through a hole in the dashboard replacing the speedo.

Visceral would be an understatement, very, very noisy yes…but the most impressive feature was the way the engine responded to the loud pedal. From my early years I am fortunate to have a natural mechanical feel for things and it did not seem to matter at what rpm Barry hit the accelerator …there was an instant shove in the back. Shifts to the next gear resulted in same thing, even at moderate rpm.

This was/is part of the magic of the car and all original Minis had this gutsy feel to them ….except one…the “970 S”. The ‘970’ being the only ‘A’ engine to have a substantially oversquare config (much bigger bore than stroke (@ 70.63 X 61.9) and became an interesting study into the whole long stroke/big bore debate. Fewer than a thousand 970 engined S Minis were built, the production terminated once the Homologation for racing had been approved. The reason was pretty simple, the small engine had become something of a screamer with excellent performance if one used the rev band… but it had lost the “grunt.” Prospective customers voted with their feet and opted for the 1071 and 1275. We will cover the exploits of the 970 in Chapter Two under racing, because in that form it became formidable.

The Basic Specs of the engines along with in-vehicle performance figures using the 998 Cooper as a reference follow:

  998 Cooper 970S 1071S 1275S
Bore 64.53mm 70.63mm 70.63mm 70.63mm
Stroke 76.28mm 61.9mm 68.28mm 81.3mm
Capacity 998cc 970cc 1071cc 1275cc
Max Power 55 Bhp/5500 65Bhp/6500 70Bhp/6200 76Bhp/5800
BHP / Litre 55 67 65 60
0 to 60 Mph 15.5sec 13.5sec 13.0sec 11.2 Sec
Max Speed 87Mph 91Mph 93Mph 97 Mph

From these figures we can see that the S range of engines provided a healthy rather than spectacular performance improvement ….that was in road trim… the secret was to be what could be achieved once the top tuners got hold of them….The scene was now set for the Mini to write a chapter in motorsport that is quite unique and…amazingly… remained alive for an inordinate amount of time.

To close this part one of the Cooper ‘S’ story, I thought it appropriate to include the following Downton advert covering the tuning of both the 998 and 1275 packages available to enthusiasts in that wonderful mid 60’s period. Can you imagine just how exciting this was for all those involved at the time. Put simply, for a fraction of the total cost, here was a package (the 1275) that could comfortably destroy a Lotus Cortina in acceleration and match it on top speed. Saloon cars had gone from ‘humdrum’ to ‘explosive’ in a flash….

Downton Tuning Advert

Typical 997, 998,1098 Bore spacing

…We get to this fabulous world of ‘A’ engine tuners and racing/rallying in part 2 of the Mini Cooper S story.