The MGA With An Attitude
DEMONSTRATION DAY - July 14, 1958* - TC-130I
Launch of the MGA Twin Cam - (Pg 9)

(*various reports of the actual day of demonstration, 14, 15, 16, or 18).


High-speed run for two on the banking at Chobham.

Twin Cams for Performance
A brief assessment of the new Twin Cam MGA

S a preliminary to the announcement of the new Twin Cam MGA, the Nuffield Organization held a demonstration day at the Fighting Vehicles Research and Development Establishment at Chobham, the purpose being to allow journalists to make a brief assessment of the car on the closed, high speed circuit. IN addition there was provided an opportunity to renew acquaintance with those other cars of the Nuffield range who's "sporting" characteristics are generally acknowledged -- the MG Magnette, the Riley One-Point-Five, the Morris Minor 1000 and, of course, the standard MGA in Coupe form -- on a section most appropriately named the Snake Course: as if this were not enough a similar selection of cars was made available for the ascent of a series of Test Slopes.
In such a setting, and under conditions which might represent an approximation to the Paradise for many SPORTS CAR readers, the only snag was that time and demand meant that only three laps of the High-Speed Course could be completed in a "Twin Cam." Thus the highlight of the day was over in less than five minutes, which is hardly time to form clear and determined impressions of the car.
First and foremost, however, the Twin Cam MGA provides an exhilarating ride and has a performance which puts it in an altogether different category from the standard car -- which will continue in production unchanged. This is not to suggest that the standard is no longer worthy of


consideration. -- far from it; for most needs, and most roads, in fact, the performance of the 1489cc pushrod engine is more then adequate, and three laps of the Snake Course in the standard coupe' made it clear that this is an extremely good conventional design. Its road holding verges on the miraculous and even when the tail has been made to slide to an extent which in most other vehicles would automatically result in a spin, the car remains perfectly balanced, responding sweetly to correction but never losing its temper even under acute provocation. Whereas another car, of similar engine capacity and power output, weaved rather alarmingly when the foot was lifted in the middle of a corner, the standard "A" adjusted itself immediately to this bad driving and serenely followed its appointed line.
Thus in any comparison which may be made it is necessary to judge the "Twin Cam" not so much as an improvement on the original model but as an entirely different car. The combination of increased capacity (to 1589 cc) and double overhead camshafts not only results in a great increase of power and torque, but also gives the engine an entirely different character. At first it seems a little strange to find the engine of a production car running up safely to 7000 rpm, with the peak of the power curve at 6700 rpm. The recommended limit for gearchanging is 6500 rpm, and from a standing start this figure is reached -- the speed being just over 30 mph -- in about three seconds.



The gear change is one of the best in the world and the car maintains its headlong rush in second and then in third, reaching eighty in about half the time required in the standard model, while the maximum speed in third is about 85 mph. From 90-95 mph the frontal area of the touring windscreen begins to have a real affect on acceleration and that last 5 mph to the "ton" take longer than the first 50 from the starting point. Our brief test was carried out on a very short straight, however, and there were still over 1000 rpm to come when it was time to brake and change down for the long left hand corner.
The chief attribute of the new car is thus its ability to reach high speed very quickly and to maintain them through corners, thanks to the road holding qualities already extolled on the standard model.
The Dunlop disc brakes also play their part in the overall picture of high performance, a mere touch sufficing to slow the car and steady it on the approach to a corner, while firm application from high speed results in a smooth and progressive deceleration -- in a straight line -- the "feel" of the pedal giving the driver far more confidence in the car's ability to stop than is the case with almost all production drum brake systems.
Since use of the Ministry of Supply's track at Chobham is somewhat restricted (and most of those who have used it will not have done so at the wheel of a real sports car) it may be worth while to give a brief outline of the plan of the circuit, and of the "Twin Cam's" performance on it.
From the starting point the track curves away to the left and is banked towards the outside. A combination of shallow banking (designed for lorries to run "hands off" at 45 mph) and rough surface (too many lorries) results in a need for a

Twin cam head takes up much of the underbonnet space on the MGA. With a compression ratio of 9.9 to 1, the 1589 cc engine develops 108 hp at 6700 rpm. Stages of tune are being developed in the usual way. Because of the extensive modifications required, it is impossible to convert standard cars to the Twin Cam specification.


Dunlop disc brakes, with 11-inch diameter discs, are fitted to all four wheels.

more or less normal driving technique -- much as used on the well-cambered bend -- but this corner goes on and on through about 150 degrees. There follows a short straight, on which it is possible to get into fourth gear before a swerve to the right, preceded by a bump which tends to throw the MGA sideways -- from which the car recovers most admirably -- and then a kink back to the left which marks the beginning of a long wide-radius curve, again slightly banked. This turn can be taken virtually flat out in third, thanks to the car's excellent road holding and responsive steering. At 6800 rpm a straight-through change into top induces very little clutch slip, and the car goes on accelerating through the long, long left-hand curve which leads back on to the circuit's one short straight. There is just time to get the speed up to 100 mph before braking and changing down for the first corner, and that's two miles in just under one and a half minutes, a figure which could be improved upon quite considerably upon further acquaintances with both course and car.
A lasting impression of the Twin Cam MGA is its "fruity" exhaust note, combined with a hard and -- to the enthusiast -- joyous mechanical noise from under the bonnet. Outwardly it can be distinguished from the standard car only by its centre-lock disc wheels and TWIN CAM motifs on the scuttle and boot lid.
It remains purely two-seater, with rather restricted space in the luggage boot, and this alone will prejudice some prospective owners. However, the "Twin Cam" will initially be produced only in limited numbers and preliminary orders from the United States and Canada alone will account for the first seven months' scheduled production, earning well over a million dollars.
In international rallies (towards which its increased engine capacity is largely directed) and production sports car races (for which purpose the usual MG "Stages" of tune are being developed) the Twin Cam is certain to prove a strong contender. And on the road it will provide really exhilarating motoring.

AUGUST 1958  


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