COOPER POWER FOR THE B.M.C. 1100
MOST modified cars which come our way have had alterations made to the existing power unit, and while this is normally satisfactory there are sometimes drawbacks, such as inflexibility, harshness or a much higher noise level. Janspeed, who share the Salisbury region with another exalted company to do with B.M.C., have introduced a version of the Austin or Morris (Riley or Wolseley, come to that) 1100 fitted with a standard Cooper S 1,275-c.c. engine. In our opinion the result is most pleasing, quite transforming a rather gutless pudding into a rapid grand touring model.
Just why B.M.C. don’t do this themselves is surprising, now we have sampled the effect. There is an old saying that there is no substitute for litres, and if an extra 177 c.c. doesn’t sound much, it makes a heck of a difference when another 24 b.h.p.— just 50% extra—is available. When men grow out of their Mini-Coopers, as inevitably happens, they have really been forced to go to Dagenham for an effective GT replacement, but the Janspeed 1100 does offer the advantages of front-wheel-drive and B.M.C. compactness allied with 94 m.p.h. top speed and brisk acceleration to 60 m.p.h. in 14 seconds.
The cost price of this straight engine change is £195, plus a brake booster if you want it at £18. Without doubt the 1100 engine could be made to give this sort of power at less cost, but it certainly would not be such an untemperamental, effortless car to go around in.
Performance is far better than that of an M.G. 1100, for instance, and practically as good as a Cortina GT. Comparative prices are £755 for the M.G. four-door, £820 for the Janspeed 1100, and £825 for a Cortina GT.
There are no special problems attached to dropping a Cooper 1275 block into the engine space, though the gearbox had to be altered slightly in respect of the change mechanism. The standard gearbox casing and ratios are retained, but a 3.77 final drive is taken from an ordinary Mini-Cooper to counteract the overall ratio increase due to the larger wheels. As a result the speedometer and odometer are slightly haywire, reading 8.5% slow, and this has to be taken into account if the Law appears in the mirror.
The driveshafts are not modified, and any reservation about the engine-change goes to this department. There is room in front of the block for the big brake servo unit, and another extra on the test car was a pair of Maserati twin-tone air horns.
A normal Cooper 3-branch exhaust manifold is coupled to 1,4 large-diameter exhaust system, and naturally the Janspeed car is noisier than the ordinary 1100, but not unpleasantly so. The two 1½-in. S.U. carburetters have pancake filters to deaden the noise and extra soundproofing is fitted under the bonnet and on the bulkhead. As soon as the engine is started it is obvious that this car is out of the ordinary, having the characteristically “heavier” and rougher engine note of a 3-bearing 1275.
The performance much more than compensates for this. As the ratios are fairly widely spaced the performance is fairly constant right through the range, starting with spectacular wheelspin on dry roads and ending with quite restful cruising in the high 80s, the torque of the bigger engine taking the car comfortably through the potential flat-spot regions after each gear-change.
With this engine the 1100 becomes a very different car, tremendously responsive to throttle pressure. A heavier steady-bar between the engine and bulkhead does not prevent torque tremor being felt through the car when it is gunned in bottom gear, but as the Cooper clutch is fitted (having stronger springs) there is no protest from the transmission. Except for the non-synchromesh 1st gear the gearbox is quite delightful, whipping through quickly and easily from one ratio to the next, though care has to he taken rushing from 2nd to 3rd as the spring against reverse gate is too weak. It is the extra power available to counteract the fall-off as a higher gear is selected that makes the Janspeed especially pleasant for people used to the 1100.
Of course the 1100’s Hydrolastic suspension is ideal for extra performance; it works so much better than on a Mini driven in anger! With more power to pull the car out of the corners it feels very safe to drive quickly, and even the rather low-geared steering does not call for adverse criticism. Some enthusiastic driving on winding roads at night made the front (disc) brakes smoke, but the power-assisted system remained light and responsive. Better lighting would be called for in keeping with the higher performance, and the lack of support in the seats is especially pronounced.
Apart from the slow speedometer, the conversion seems to have a disadvantage in that the exhaust booms loudly on over-run at about 70 m.p.h. The fuel consumption, working out at 25.3 m.p.g., was no worse than we would have expected during a modified car test. We also found that the throttle had a sticky movement, this being simply a case for slight adjustment on the throttle spindle; nylon cables always seem better for these cars.
It was something of a surprise to us that the Janspeed could comfortably exceed 90 m.p.h., although the performance does tail off after 80 m.p.h. Presumably the extra weight of the 1100 is partly counteracted by suitable gearing and possibly a more efficient frontal shape. Maximum speeds in the gears, except for 1st and perhaps 2nd, were definitely dictated by breathing rather than valve-bounce, and there was no point in going beyond 30, 55 and 75 m.p.h. in the intermediate ratios when taking acceleration figures.
The workmanship was a credit to Janspeed, whose immaculate competition cars are driven by Geoff Mabbs with success this year—John Fenning used to drive for the company.—M. L. C.