Mini – classic : The tuned cars

Minis are fun – such fun that most people think they need more power.

Ian Nicholls guides us through some of the tuned Minis offered for sale in the UK over the years…

THE arrival of the BMC Mini in 1959, with its roller skate handling, was of great benefit to the British performance tuning industry. Firms which had cut their teeth on the A-series engine, when installed in the Austin A35, soon applied their know how to BMC’s new baby. The best known firm was Downton engineering, which soon became the BMC approved tuners, and then became involved in official BMC engine development.

The following is a summary of tuned Minis tested by the motoring press. It is interesting that many conversions employed much wilder camshafts than would be recommended today, and many tuned Mini 850s retained drum brakes.

Many tuning packages were aimed at Mini 850 owners who wanted Cooper performance on a budget. The sheer volume of Mini road tests indicate what a fashionable car the Mini was in the Sixties.

Tests of competition cars have not been included, only tuning packages that were commercially available to the public.


12 February 1960, ARDEN AUSTIN Se7en

THIS was an Austin Mini 850 modified by The Arden Racing and Sports Cars Ltd, Penn Lane, Tamworth in Arden, Solihull, Warwickshire. Arden had been founded by Jim Whitehouse. The cylinder head was polished, the ports cleaned up and the compression ratio was increased from 8.3:1 to 9.5:1. The car employed twin 1.25-inch SU carburettors on a pre-fabricated inlet manifold, as well as a new exhaust manifold and performance air filters.

Total cost £38 5s. This conversion boosted maximum speed from the standard car’s 74mph to 85mph, and the 0-60mph time dropped from 26.5s to 20s.

Sports Car World

July 1961, Downton Engineering Conversion

THE July 1961 issue of Sports Car World, featured a test of a Morris Mini Minor 850 fitted with a £40 Downton Engineering conversion. The car was owned by Biggleswade BMC dealer Ian Mantle. The conversion consisted of a modified cylinder head, with an increased 9.0:1 compression ratio, larger inlet and exhaust valves, twin 1.25-inch SU carburettors on a new manifold, and an exhaust manifold fitting onto the standard exhaust system. The 0-60 time was 19s and a top speed of 95mph was claimed.


4 August 1961, Yimkin Conversion

IN its August 4th 1961 edition, Autocar tested a more modest conversion.

Yimkin Engineering Ltd, 73-79 Cadogan Lane, Sloane Street, London, SW1, for the pricely sum of £18, sold its ‘Stage 1’ kit. The kit consisted of a modified cylinder head and a new SU carburettor needle. The 0-60 dash was attained in 21.3s, and top speed was 77mph.


November 1961, Downton Engineering Conversion

AUTOCAR’s December 8th 1961 road test, headlined “Mini-Ton-Bomb”, was one of the most significant road tests of all.

The test of a 997cc Mini Cooper, 860 MW, modified by Downton Engineering in Wiltshire. The engine block had been bored out to 1088cc, the cylinder head gas-flowed, fitted with larger valves, the camshaft re-profiled, and added to this mix were twin 1.5″ SU carburettors and a performance exhaust. The 0-60mph time was reduced to 9.6s and top speed was a remarkable 103mph.

Autocar commented: “A direct result of this is a marked gain in torque,but the chief object of the conversion as a whole has been to provide outstanding tractability and top gear acceleration over a wide engine speed range, rather than the ultimate in top speed. ”

Autocar journalist Ronald ‘Steady’ Barker was so impressed with this car that he phoned Alec Issigonis at Longbridge. Issigonis demanded to see the car, and after a test drive sent for Downton boss Daniel Richmond. Richmond was appointed as a consultant to BMC with an office at Longbridge.

Daniel Richmond was to contribute towards BMC engine development for the rest of the Sixties.


27 July 1962, Downton Engineering Conversion

IN its July 27th, 1962 edition, it tested 860 MW the Downton Mini Cooper. The magazine achieved even better figures than Autocar, obtaining a top speed of 108mph and a 0-60mph time of just 8s.


10 August 1962, VW Derrington Conversion

THE tuned Morris Mini 850 modified by V.W. Derrington Ltd of 159-161 London Road, Kingston-upon-Thames, Surrey.

The car tested, 754 PBB, was a 1960 car owned by Vic Derrington, the firm’s boss. The cylinder head had been gas-flowed while retaining the standard valve sizes, and the compression ratio raised to 9.3:1. The camshaft was the hotter 88G229 as used on the 997cc Mini Cooper, and a performance exhaust system was used. Carburation was provided by a twin choke Weber.

754 PBB also had another period accessory: an SPQR remote gear change.

The performance parts added around £52, but gained the buyer a 0-60 time of 14s and a 90mph top speed – yet retained a flexible engine.


14 September 1962, Alexander Engineering Conversion

ALEXANDER Engineering Co. Ltd was based in Haddenham, Buckinghamshire, where it sold car accessories until 1997.

The 997cc engine block was bored out to 1122cc, and a wilder camshaft was fitted. The cylinder head was extensively modified with a 9.5:1 compression ratio, carburation was provided by twin 1.5-inch SUs on a modified inlet manifold, combined with a three branch exhaust manifold. The 0-60mph time was reduced from the standard car’s 18s to an impressive 10.7s, and top speed went from 85mph to 100mph.

It cost £125 in kit form.

Motor Sport

August 1963 Nerus Engineering Conversion

ACCORDING to the article, the Nerus Engineering Company was an offshoot of Rother Ironworks, and was based in Rye, run by Frank Webb.

The magazine tested a Mini fitted with a Nerus modified Stage 3 cylinder head, with a raised 9:1 compression ratio and larger inlet valves, gas-flowed manifold and a straight-through exhaust system, all for £35.

The car could do 80mph and the 0-60 time was 20s. Motorsport felt that the kit was good value as the standard Mini was then £120 cheaper than the Cooper variant and only a little more expenditure was needed to exceed the performance of the Mini Cooper.


13 December 1963, Speedwell Clubman Mini Cooper

SPEEDWELL Performance Conversions Ltd was based at Speedwell Centre, Cornwall Avenue, London, and included Graham Hill among its directors (he appeared in its press adverts). The car Autosport tested was fitted with the higher 3.44:1 final drive instead of the then standard 3.765:1. The 997cc engine block was bored out to 1152cc, and fitted with Speedwells own design of aluminium cylinder head which had a compression ratio of 11:1.

The twin 1.5-inch SUs and exhaust manifold were also fitted. The camshaft was Speedwell’s own design the CS6 which was similar to the BMC AEA544 used in Formula Junior single seat racing cars. Speedwell claimed a power output of 82bhp at 6800rpm and 70lb ft torque at 4500rpm. Autosport achieved a 0-60 time of 8.4s, and a top speed of 109mph.

The total cost of the engine conversion was £200 or one could pay £800 for a complete car. This was at a time when a Mini Cooper 997cc cost £568 and a 1071S £695.


November 1964, Taurus Mini Cooper 1275S Conversion

TAURUS Performance Tuning Ltd hailed from 14a Thorpe Mews, Cambridge Gardens, Ladbroke Grove, London, W10. Taurus claimed 100bhp for this car, which featured a gas flowed cylinder head with a 10.5:1 compression ratio, bigger twin 1.5-inch SU carbs. The surprising thing about this car was that it was fitted with a BMC AEA648 camshaft, commonly known as the “649”. This was a racing camshaft and certainly not one that would be recomended for a roadgoing Mini today.

Autosport wrote rather confusingly: “The car is not as flexible as it might be with, all the power between 4000 and 6500rpm. However, it gives no trouble if used as a shopping car, and can be driven round town all day without oiling or wetting the plugs. For road work, I would have thought the AEA731, a much milder cam would have sufficed at the expense of slightly less performance”.

With this engine build the Taurus 1275S clocked up a 0-60 time of only 7.6s and a top speed of 112mph.

Cars & Car Conversions

December 1964 Speedwell Courier

THIS was AMH98A, an Austin Mini Traveller fitted with an 1152cc engine, similar to that used in the Speedwell Clubman Mini Cooper. In the Speedwell Courier power was up from 82bhp to 91bhp at 6600rpm, and torque was now 77lb ft, nearly the same as a standard 1275S.

In addition to the performance goodies, there were various interior trimmings including Restall front seats. CCC did express some reservations about the drum brakes, something that would not be tolerated now on such a powerful car. The Speedwell Courier was only available as a complete car, costing £850.

The top speed was 106mph and the 0-60 time was 9.8s.

Sporting Motorist

March 1965 Radford Mini Cooper de Ville based on a 997cc Mini Cooper.

ALL the luxurious coachwork added some 120lb to the car’s weight so Downton Engineering was assigned the task of giving the car some more zest. Daniel Richmond’s Wiltshire firm increased engine capacity to 1162cc, modified the cylinder head and lightened/balanced the engine to boost power to 76bhp at 6500rpm. While this was not as much as rival firms, Downton concentrated on providing useable low down torque instead of creating a stratospheric revving screamer, something that the testers commented on.

“The bored out power unit starts easily and it is immediately noticeable that torque delivery is excellent from the bottom end of the rev range.”

Downton liked to use a camshaft profile similar to that later used on the MG Metro. The engine conversion cost £190, the whole car costing £1498 and “Sporting Motorist” thought it was worth every penny. The 0-60 time was 12.7s and top speed was 87mph, not as much as expected, perhaps due to the extra weight carried.

Cars & Car Conversions

July 1965 Taurus stage 1 tuned Morris Mini Cooper 1275S

LESS extreme than the car tested by Autosport in November 1964, this car, CMO 859B, merely had a gas-flowed cylinder head and twin 1.5-inch SU carburettors, all for £53 10s. Top speed was 103mph and the 0-60mph time was 8.8s.


24 September 1965, Downton Engineering Conversion

THE magazine gave a glowing review of the factory approved souped-up Cooper S. The car tested, 777 MCG, was a Downton Engineering converted car fitted with extra soundproofing and lowered suspension. A modified cylinder head, twin 1.5-inch SU carburettors, performance exhaust, all the usual trimmings. Power output was reckoned to be 99bhp between 6000 and 7000rpm, and torque was 86 lb ft at 5000 rpm.

The maximum speed was 110mph, (it could do 100mph in third gear) and the 0-60mph dash was dispatched in a mere 7.8s.

Autosport concluded: “This well behaved touring car is more fun than most sports cars. It’s remarkably smooth and by no means noisy, while it travels easily at speeds which are normally in the province of costly GT models. Nothing could be more fun to drive,and a smooth engine must last longer than a rough one.”

Praise indeed, but Downton was the factory approved tuner because it was the best.

Cars & Car Conversions

January 1966, Broadspeed Cooper 1275S

MODIFIED by Broadspeed Engineering Ltd of 101 Stratford Road, Birmingham, the Cooper, 5 NOB, was owned by Birmingham solicitor Mr P. Perrey.

Broadspeed was founded by Ralph Broad, and had scored success on the race track using Minis. However by the time this article was published, irked at the lack of BMC support, Broadspeed had defected to the Ford camp to run Anglias and, later, Escorts. However it continued to supply tuning goodies to road going Minis. 5 NOB had Broadspeed’s ‘One Hundred Pound Conversion’, which consisted of the usual gas-flowed cylinder head, with 10.5:1 compression ratio, twin 1.5-inch SU carburettors and performance exhaust system. The camshaft was described as “road/race”. CCC described the tickover as being around 1100 rpm, and the power kicked in around 3000rpm – and then just kept on coming. The maximum speed was 113mph and the 0-60mph time was 8.5s.

In conclusion CCC stated: “One way or another, it seems that the hundred quid asked by Broadspeed is well worth spending. You get a car which is faster than standard and, at the same time, is a damn sight more pleasant to drive or ride in.”

Broadspeed would later return to the BL fold, it prepared the Triumph Dolomite Sprint that won the 1975 British saloon car championship in the capable hands of Andy Rouse, and in 1976 the ill-fated Jaguar XJ12 racing effort. Ralph Broad has since retired to Spain.


May 1966, Speedwell 1300TC

BASED on the Cooper 1275S, the Speedwell was an unknown quantity. The engine was bored out to 1293cc, the cylinder head gas-flowed, and the usual twin 1.5-inch SU carbs added to the mix, along with a Supertone 85 exhaust system and Speedwell’s own camshaft. The claimed power output was 90bhp at 6500rpm, and maximum torque 85lb ft at 5000rpm. Top speed was 109mph and the 0-60 time was 9.5s.

At £994, Motorsport thought it was good value for money.


16 September 1966

TAURUS Austin Mini 850 fitted with a big bore exhaust system and a Japanese Nikki carburettor and appropriate manifolds. Top speed was a dissapointing 75mph and the 0-60mph time was 24.3s. At £23 the magazine did not consider it good value for money.

Cars & Car Conversions

July 1967, Oselli 1200 Mini GT.

OSELLI, then based at Baynards Green near Bicester in Oxfordshire, but is still very much in the tuning business, although it now concentrates on tuning classic cars.

For £176 the Mini 850 owner could have his engine exchanged for something more potent. The 850 engine block was bored out and fitted with a 998cc crankshaft to increase capacity to 1198cc. This was common practice to enlarge the capacity of the smaller A-series engines to attain 1275S performance levels economically. The cylinder head was fully modified,being fitted with bigger valves and gas-flowed. Carburation was by twin 1.5-inch SU’s and a performance exhaust was fitted. The camshaft was “road/race”.

CCC recorded a 103mph top speed and a 0-60 time of 8.8s. Despite the Cooper S-beating performance, drum brakes were retained all round.

Cars & Car Conversions

January 1970, Mini Clubman fitted with BL Special Tuning parts.

CCC listed the parts complete with the part numbers, so the enthusiast knew what to ask for. The car tested, SOH 886H, was fitted with what seemed to be a race engine, complete with twin 1.5-inch SUs, AEA648 camshaft, and low 4.1:1 final drive. Despite this power available, reckoned to be 90bhp, drum brakes were retained. 0-60mph was reached in 10s, and top speed was reckoned to be 100mph.

CCC concluded: “To summarise, I can say that the 998 is very far from ‘old hat’ and, suitably modified with the Special Tuning gear tested, it’s really good. When this sort of outstanding performance and power output is available for the owner of a new Mini Clubman,then such a combination deserves very serious consideration indeed.”

Of course the Special Tuning components could also fit any other 998cc Mini, as the engine had first appeared in the MK2 Riley Elf/Wolseley Hornet in 1963.


1971, date unknown, Mini 1275GT, tuned by Downton Engineering.

DETAILS of the car are sparse, but we do know is it was nicknamed ‘Tiger Tim’ and had higher-than-standard gearing. The engine was described as being a bored and stroked 1370cc block, with twin carburettors, and a near full race camshaft, which produced 109bhp. ‘Tiger Tim’ did 0-60mph in 8.4s, and reached 104mph.


21 August 1971, Mini Cooper S, fitted with an eight port crossflow cylinder head.

THE car, VOH 347J, was loaned by BL Special Tuning of Abingdon. The block was bored out to 1293cc, fitted out with an aluminium eight-port head, with four Amal motorcycle carburettors, a full race camshaft, and a close ratio straight-cut gearbox. The car was also fitted with the low 4.267:1 final drive. The eight port cylinder head had been developed in the late Sixties by Jim Whitehouse of Arden in response to the competition from Ford’s crossflow engines.

The standard A-Series engine cylinder head, is of the less efficient five port variety, with the exhaust and inlet ports on the same side. By 1968, Cooper and other Mini teams were using the eight-port head on the racetrack, and the works rally cars used it as well. There were two versions, a fuel injected type and the Amal carburettor one Motor magazine tested.

Amal Carburettors were a tight squeeze under a Mini’s bonnet. The kit retailed by Special Tuning cost £545.11, and produced an impressive 124bhp at 7000rpm.

Motor magazine described the car as incredibly quick and very noisy, courtesy of its straight cut gearbox, and one of the testers had to wear earplugs!

Motor commented: “The temptation to blast round the countryside at full bore in this car was absolutely irresistible, an experience that no boy racer should miss. Of course we’re not saying you’ll find boy racers at Motor: it’s just that nobody with the slightest enthusiasm for driving could possibly step into VOH 347J and drive off without getting that leadfoot feeling within 50 yards.”

With 124bhp on tap, VOH347J could do 0-60mph in 8.6s, but the low final drive restricted top speed to 100mph. Eight port cylinder heads are still available from the Mini Spares Centre.


28 October 1971, Mini Cooper S, fitted with an eight port crossflow cylinder head (see above).

This picture gives a good indication of an Eight-port cylinder head and Amal motorcycle carburettors. At £545 the Special Tuning package was more than half the price of a Mini Cooper 1275S.

BY now the 4:267:1 final drive had been replaced with the higher 3.9:1 ratio. The top speed measured was 106mph and 0-60 in 9.1s.


October 1971, Sparrow Cooper S

THE magazine tested a more conventional way of improving a Mini’s performance – enlarging the engine capacity.

Will Sparrow Ltd, 2 Redditch Road, Studley, Warwickshire showed off BAC 700J, a Mini Cooper S fitted with an engine bored out to 1390cc.

The 0-60mph time was 10.5s, and top speed was 101mph. Will Sparrow’s approach was to prove the most cost effective way of making a Mini go faster – as second hand 1275cc engines from more mundane BL cars became available in the Seventies.


4 December 1971, BL Special Tuning kit for the Mini 1275GT.

THE Cooper 1275S had been axed in the summer of 1971, something which Lord Stokes has been critisized for ever since by Mini enthusiasts. What is not well known is that the much maligned 1275GT could be brought up to ‘S’ performance levels with a BL Special Tuning kit, C-AJJ 4082. This consisted of a polished cylinder head, additional 1.5-inch SU carburettor, and a twin carburettor inlet manifold and air cleaners, all for £125.

At the time a 1275GT cost £898 new, and a 1275S (in May 1971) cost £1058, a difference of £160. So “S” performance was available if the buyer so desired. Motor magazine felt the 1275GTS (as it was dubbed), was as competitive as the old Cooper 1275S, they just didn’t think it felt the same. Top speed was 94.9mph, not quite as fast as the 1275S. This was probably down to the less aerodynamic Clubman nose, but acceleration was superior, with the 0-60mph being dispatched in 10s.


1973 – date unknown, Downton tuned Mini 1275GT.

In the article, Autocar decribed the recently deceased Mini Cooper S as being overpriced and under-equipped in comparison to the 1275GT, and described the latter’s performance as only “slightly down” on the 1275S.

So much for the contemporary press viewing the 1275GT as a pale shadow of the Cooper S. The 1275GT Autocar tested had been fitted with a Downton Touring conversion, which involved changes to the top end of the engine. The cylinder head was modified and fitted with larger inlet valves and the compression ratio was raised from 8.3 to 9.5:1. An ADO16 1300GT distributor was used along with a Downton long centre branch exhaust manifold and system. The car was fitted with twin 1.5-inch SU carburettors and retained the standard camshaft.

The cost of this was £146.79 (excluding VAT).

The result of this tweaking was seen on the road. The standard 1275GT Autocar tested in September 1971 struggled to 90mph and accelerated to 60mph in 13.5 seconds. The Downton 1275GT attained a more impressive 105mph and did the 0-60mph dash in 11.5 seconds, only marginally less than the defunct 1275S.

Autocar said of the car: “The cross country performance of the Downton converted car is quite amazing, and the ability of the car to regain its high cruising speed after any sort of hold up gives remarkable journey times… There were no signs of any temperament from the converted car,and this conversion should appeal to anyone looking for the handiness of a Mini and the performance of a much larger engined car.”

However the days of Downton engineering were numbered.Founder Daniel Richmond died in 1974 and his widow committed suicide in 1975 and the firm closed down.

Mini in abeyance

BY the early Seventies, the Mini was no longer fashionable, and the flood of tuning gizmos stopped. Some tuning firms disappeared or diversified into other fields. In August 1979, Motor magazine caculated that a Mini ftted with the then-standard 3.44:1 final drive needed to rev to 6250rpm to attain 100rpm. The peak power of the standard Cooper 1275S was 76bhp at 5900rpm, which pushed it to 97mph.

In the late Eighties, demand for hot Minis again built up.


7 March 1987, Sussex Performance Engineering modified Mini

THE test car, D951 WRP, was a Mini Mayfair fitted with a 1400cc engine. By the Eighties, tuning fashion had turned against multiple carburettors and very wild camshafts. Carburation was provided by a single SU HIF44, or 1.75-inch SU (in old money). The performance figures justified this approach as 0-60mph was attained in 8.5s, and top speed was 104.5mph.

Motor wrote: “In truth, I’d forgotten what a Mini’s handling was like: now I’ve remembered, I’m unconvinced that all the dynamic progress made in small car design has been positive.”

The Mini SX retailed for £5862 plus £185 for Minilite-style wheels. 35 were made before SPE closed.

Autocar & Motor

14 June 1989, Mini Racing limited edition (John Cooper Garages kit)

DESIGNED to boost power from the 998cc engines measly 40bhp to 64bhp, the kit previewed the birth of the SP Cooper. The power increase was achieved with the help of Janspeed Engineering, which supplied a modified cylinder head with bigger valves, a performance exhaust system, twin 1.25-inch SU carburettors and manifold, and performance air filters.

The higher 3.1:1 final drive of late Eighties Minis probably restricted top speed to 88mph, but the 0-60 time of 13.2s was much superior to the 18- to 19-seconds of the standard Mini.

Even in the late Eighties, the Mini had a habit of winning over journalists, who probably expected to condemn it as a relic of a bygone era. Autocar & Motor thought the John Cooper Garages kit at £1275 (plus VAT) was worth every penny. By now, John Cooper was back in the Rover fold, so the kit was available at all Rover dealers, and included in the warranty.

Popular Classics

January 1990, three tuned Minis.

THE BAC M-30 was a limited edition of Mini Thirty Special Edition. BAC was based in North Perrott, Somerset. The interior was luxuriously trimmed – all leather and walnut veneer, while the exterior ‘improved’ by the addition of a KAT Designs bodykit. Motive power was provided by a 1275cc engine, mated to a Sprintex supercharger, to provide 115bhp. This propelled the car from rest to 60mph in 8.7s, and on to 111.6mph. The original asking price of the BAC M-30 was a staggering £30,000, later lowered to £23,390.

The ERA Turbo which retailed at £11,950 at selected Rover dealers, was developed by ERA at Dunstable. The car was basically a Mini fitted with 13 inch wheels, a bodykit designed by Dennis Adams of Marcos, and fitted with a 94bhp engine, as fitted in the MG Metro Turbo. With this power unit the ERA Turbo could do 0-60mph in 9.9s and reach 101.7mph. Some 400 were built between 1989 and 1991.

The cheapest car tested was the Avonbar Mini 30. Avonbar was founded by Ian Hargreaves in 1975 and based in Addlestone, Surrey (it still exists). Its conversion, known as the ZX, involved boring out the 1275cc engine to 1380cc, gas-flowing the cylinder head, and fitting larger valves. Traditional stuff then, but it did produce a useful 104bhp. For this, Avonbar charged £1994 for the conversion. The 0-60 time was 8.8s, and top speed was 100.6mph.

In conclusion, the testers dismissed the BAC M-30 as too expensive – it cost the same as a BMW 535 or a Rover 827 Vitesse – and decided between the ERA Turbo and the Avonbar Mini 30. In the end they plumped for the Avonbar, as it was the best value for money.

Autocar & Motor

May 1991, RSP Mini Cooper (Cooper garages ‘S’ Pack)

THE testers experienced deja-vu with a car that died two decades before, and then returned from the dead. In July 1990, the Rover Group had re-introduced the Mini Cooper, by the simple expedient of fitting the Mini with a detuned catalysed MG Metro engine, producing 61 bhp. In 1991 John Cooper garages introduced the ‘S’ pack and made it available through Rover dealers.

The kit itself was manufactured by Janspeed Engineering, which had produced JCG’s previous kit for the Mini 1000. Janspeed had been founded by Hungarian refugee Jan Odor, after he left Downton Engineering in 1962, and by the late Sixties, was contributing to the BMC 1800 works rally cars. Jan Odor proved to be an excellent businessman, as well as a brilliant engineer. His company thrived to the present day, while his rivals wilted.

Janspeed’s kit consisted of a big valve gas flowed cylinder head, exhaust system, twin 1.25-inch SU carburettors, and high lift rockers. This little lot boosted power to 77bhp. The feeling of deja-vu also extended to the road test results, which bizarrely echoed that of 1964 and the original 1275S. Top speed was 97mph and 0-60mph was reached in 11s.

Autocar & Motor commented about the undead Mini Cooper S: “Judged by most rational criteria, the Mini Cooper S fails as a car for the Nineties. It’s noisy cramped, uncomfortable, unrefined, and yet over the top with its plethora of badges. By today’s standards, it’s not even particuarly quick and, of course, it’s astronomically expensive. Are there any other cars out there with sporting pretensions that only have four speeds?

“But in one respect at least, the Mini succeeds brilliantly. Its a magnificent car to drive, responsive in a way that nothing for a comparable price can equal, never mind surpass. You don’t take the Cooper S to work, you drive it, and if you’ve forgotten the fun that can be had from driving then you need a car like this to remind you.”

What Car?

October 1992, Mini Cooper Si

THE testers were less enthusiastic about the 77bhp Cooper Si, which they thought was for enthusiasts only. The latest version of JCG ‘S’ Pack was for the fuel injected Mini Cooper introduced at the end of 1991 to meet tightening emission regulations. What Car? could only attain 93mph, although the 0-60 time was reached in 11.2s, the same time as Autocar magazine achieved with the 1275S in 1964.


September 1995, Mini Cooper Si

THE magazine looked at the latest Mini Cooper Si. By now, the car was only available from John Cooper Garages, although it was still covered by Rover’s warranty.

By now JCG was selling the car to Formula 1 personalities who could afford much faster toys. The latest Cooper Si boasted 83bhp, which at last pushed the factory backed Mini Cooper to a three-figure top speed. Maximum speed was 101mph, and the 0-60 time was down to 9.9s. Car magazine liked the car, but thought that at £9975, one could buy an old Mini and tune it to around 100bhp.

Current scene

By the Nineties, the tuning scene, which the Mini had helped to foster, had changed. The “Cruising” culture has seen demand concentrate on loud exhausts and even louder car sound systems.

With so many turbo cars on the market, tuning is a simple case of fitting a dump valve and water injection. Many tuners make their living from tuning classic cars from the Sixties and Seventies, (Oselli is a case in point; its 1950cc MGB conversion is highly regarded). The Mini tuning boom was in part caused by poor BMC product planning.

One had to modify the engine because there was no cheaper alternative. Nowadays, engine interchangerbility is more common between models. Many a slow Vauxhall Nova/Corsa has been transformed by the transplant of a two-litre engine from its bigger GM brothers. And a K-series Metro can be fitted with a 1.8-litre version of the engine.

Fitting a 1798cc B-series engine into a Mini was never practical!

By the current decade, the Mini tuning scene had drifted towards Vauxhall, Honda and Rover K-Series transplants, complete with modern 5 speed gearboxes. These came with subframes supplied by firms such as Watsons, Rally and AMT.

Unfortunately no-one has seen fit to roadtest and gather some actual performance data…

Keith Adams


  1. Mmmm…
    Takes one back.
    I remember fitting a 12G295 (or was it) head, an AEA648 cam, two HS4s and a manifold from where?
    I got the gearbox – straight-cut a scraper from Morris Engines in Coventry!
    It all worked well until one day I floored it off the lights in Cox Street, Coventry and the timing chain gave in!!!
    A duplex chain solved that one.
    It ran well for a year or so then I hit a cow on my way home one night!
    I have no idea who bought the power unit, the body 8208UB was scrapped.

  2. More power! Always remember the wisdom of the saying, “Too much is barely enough!”

    Don’t forget about the vasious bike engine conversions. Some of those a very well done. And then there are hybrid affairs wherein allow dohc heads are grafted onto the Mini’s cylinder-block.

    Still, by far the best Mini conversion I have seen lately is the one done by those wild Australians at “Mighty Car Mods”. Look them up on youtube and follow the multi-episode series as Marty and Moog transplant a Honda B-series VTEC engine and transmission into a Mini to make it work as it ought to. Best of all, they eliminated that appalling whining Mother-in-Law sound from the transmission. Peace at last!

  3. Were you aware of the photograph of 860 MW competing at the WECC Stapleford Hill Climb on 8 October 1961? It’s in Autosport 13 Oct 1961 p497. The reporter suggested it was the first competition appearance of “the new Cooper-Austin”. It finished second in class behind a “hot Anglia”.

  4. It is interesting to compare the seemingly varying figures for the 83 hp Cooper Si and other versions with the 1999 90 hp Cooper Si (or apparently known as the Cooper LE S Works), since the latter reputedly managed to achieve 0-60 in 8.9 seconds and maximum speed of 101 mph (other sites claims 0-60 in 9.3 seconds and 108 mph).

  5. If the Classic Mini tuning boom was caused by poor BMC product planning that entailed modification of the engine in the absence of a cheaper alternative, combined with the inability of the A-Series to grow beyond 1275cc.

    Would it have been possible for BMC to develop an indirect 1000-1600cc replacement for introduction in the early/mid-1960s based on A-Series principles (plus South African engines and A-OHC prototype) with a bore range of 70.6-76mm and a stroke range of 62-88mm (larger 1400-1600cc versions appearing first followed later by smaller 1000-1300cc variants), as embodied in the Nissan A OHV later Nissan E OHC engines (both being in production from 1966-1996) in place of the unbuilt narrow-angle V4/V6 engines?

    Especially one that not only slots between the A-Series and B-Series, but is lighter (or at minimum roughly the same weight) compared to the A-Series (unlike the E-Series) yet still able to easily slot into the engine bay of the Mini as well as used by other BMC models like ADO16, MG Midget, etc?

  6. Not mentioned would be the John Cooper Garages 1400 Conversion Kits that appeared from 1992 and ranged from a 1400 Injection kit putting out 108 hp to allow a Mini to reach 60 in 8 seconds / top speed of 108 mph as well as a 1400 Carburetor Kit putting out 115 hp to allow a Mini to reach 60 in 7.95 seconds / top speed of 110 mph.

  7. That photo of UHR 850 Mini above, reminds me of my first 1967 Mini 850. Paid £275… Same colour and grille etc. (though not tuned). Happy first steps into car ownership.

  8. When i was at Longbridge 1966-68 Alec Issgonis had a 1275 Cooper S fitted with a reworked Downton engine and AP auto transmission, it used to snap the main shaft until a strengthened unit was fitted.

  9. In the early early 70’s I fitted a 1098 cc engine to my 1962 Mini. The engine/ gearbox included 12G295 head, single 1 1/2″ SU, duplex timing gear, 3.44 diff.
    This all worked very well, car would easily pull over 6000 RPM in top gear. equating to over 100 MPH That was regarded as a rev limit as it is a long stroke engine. I still have the car.

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