sporting cars on test
SPORTING CARS ON TEST. THE 4 LITRE INVICTA. By HUBERT H. S. KEOGH.
SPECIFICATION. 41/2 LITRE INVICTA.
Engine.—Six Cylinder, bore 88.5 mm, stroke 120-64 mm, capacity 4,467.26 c.c., Treasury rating 29-12 h.p., tax £30, overhead valves operated by push rods.
Gearbox.—Four forward speeds and reverse, ratios : 11.3 to 1, 7.5 to 1, 5.2 to 1 and 3-9 to 1.
Suspension.—Semi-elliptic springs front and rear controlled by Hartford Duplex Shock Absorbers.
Brakes.—On all four wheels. Six sets of brake shoes, two on each of the rear wheels and one on each of the front wheels.
Lubrication by Enots Autoram gun.
Wheels.—Rudge Whitworth detachable wire wheels are fitted shod with 30 x 5.25 Dunlop tyres.
Chassis Weight.-25 cwts.
Electrical Equipment.—Rotax 12 volt. Exide twin starter batteries. Accessories.—Clock, speedometer, radiator ther
mometer, cigarette lighter. Klaxon and Bosch horns. Full kit of tools.
Speeds on Gears :— 2nd, 45 m.p.h. 3rd, over 70 m.p.h. according to
4th, top, over 85 m.p.h. type of body, etc.
Price.—Chassis £985. Manufacturers.—INVICTA CARS, LTD.,
11 Albermarle Sreet, W. I.
Though not sold as a super sports car, the 4/2 Litre Invicta, with its exceptionally high performance, can hardly be classed as a touring car, yet it is probably one of the most ideal cars made for this purpose, owing to its wonderful top gear performance, but at the same time if full use is made of the gearbox and the car's terrific acceleration, there are few super sports cars which can equal its performance. It will accelerate from 10 miles per hour to 90 miles per hour in top gear in 33 seconds ! and yet in spite of this, with a /9 to 1 top gear it will climb Netherall Gardens, Hampstead at 10 miles per hour with a rolling start of about 4 miles per hour in top !
This staggering performance is not due by any means to the fitting of a super efficient engine in a very light chassis, since the chassis weight, 25 cwts., is only slightly below the standard for a car of this size, and the car which we tested was fitted with a four door Weymann Saloon body, which brought the total weight up to 31 cwts.
105 H.P. AT 4,000 R.P.M. The six cylinder monobloc engine has a bore of 88.5 mm and a stroke of 120.64 mm, which give a cubic capacity of 4,467 c.c. Its effective speed range is from about 200 r.p.m. to 4,000 r.p.m. when it develops 105 h.p. The crankcase, which is made of light alloy, is a stiff rigid casting, and acts as the engine frame. The valves, which are set in the detachable head are operated by push rods and fitted with duplex concentric valve springs. The sump is
ribbed for cooling purposes.. The crankshaft is mounted in four bearings and its journals are of extra large dimensions.
SPORTING CARS ON
Twin ignition is fitted; coil and magneto, with of course two plugs per cylinder. The distributor and make and break are driven off the end of the generator and are very accessible. The generator, camshaft and magneto are chain driven.
Two carburettors are fitted and fed from an autovac tank which draws the petrol from the 12 gallon tank mounted at the rear. There is an auxiliary 2 gallon tank mounted in the scuttle which acts as a reserve and is gravity fed.
The gearbox has four forward speeds and reverse, and is fitted with right hand change. The steering mechanism is of manes design and the steering wheel is I 7ins. in diameter.
Transmission is by means of an open propellor shaft to the back axle which is of the half floating spiral bevel driven type. Semi-elliptic springs are fitted front and rear. The brakes, six in number, are interconnected to the pedal which operates one set of shoes on each of the four wheels. The hand brake operates one set of shoes on each of the rear wheels only.
ON THE OPEN ROAD. After climbing Netherall Gardens we proceeded to see what speed the car would attain and were amazed with the acceleration which the car has in top gear. When once the engine is sufficiently warm the throttle pedal can be suddenly depressed to the full when the car will immediately surge forward as if it is being pushed from behind. The car will accelerate from 10 m.p.h. to 60 m.p.h. in top gear in
S seconds, and if third gear is employed this time can be reduced to 121/2 seconds. At 50-60 m.p.h. the engine is vibrationless and the transmission absolutely noiseless. On touching 70 m.p.h. for the first time the car developed slight steering wobble, but after having stopped and tightened up the front shock absorbers and steering damper we had no further trouble on this score even
when this speed was exceeded. The maximum speed attained shortly after was just over 80 m.p.h., more could easily have been accomplished had opp ortunity presented itself, but it was necessary to close the throttle while the engine was still picking up. At this speed the car held the road very well indeed, in fact, I had no idea we were doing anything like eighty. The suspension at all speeds is beyond criticism, and in spite of the saloon body very fast cornering can be indulged in. The silent gearbox permits a very fast slip change to be made without in any way stressing the transmission. There is no need to double declutch when changing either up or down. The lowest speed at which the car will run in top gear is 6 m.p.h. and this without transmission snatch or judder. There is no need whatever to use any gears except second and top since the car will go practically anywhere in top, including traffic, and if brought to a dead stop the most rapid acceleration can be obtained in second, and top gear can then be again engaged.
As one would expect on a car of this calibre, With such a good turn of speed the brakes are excellent. Though not servo operated, they are very easy to apply and are progressive in action. When applied to the full either on the straight or on curves there is not the slightest tendency for the car to deviate from its course. The handbrake which operates on the rear wheels only is really more for parking than anything else, but at the same time it is quite efficient. At all speeds the steering is very light and accurate, but the lock appeared to us to be on the small side for a car with such a short wheelbase.
The car which we tested had been used for some time for everyday road work, and this must be taken into consideration when its performance is considered.
SPORTING CARS ON
FULL RANGE OF COACHWORK. The manufacturers do not supply standard types of coachwork as they maintain that compromise bodies intended to suit all tastes will probably fail to satisfy any, which is quite true with a car of this description. The prospective purchaser can therefore obtain just
the type of body he wishes, the manufacturer's only stipulation in this respect being the weight, since they will give no guarantee with their normal chassis if the complete car weighs more than 31 cwts. The makers usual guarantee is for three years or 20,000 miles and the chassis costs £985.