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Alvis Speed Twenty 1932 - 1936

our thanks to the Alvis owners club

 

The SA Speed 20, the first new post-vintage design, is for many the most desirable Alvis: fast and handsome with tremendous performance and a low, purposeful appearance. As the thirties wore on, weight and complexity set in, resulting in ever larger engines for only slight increases in performance. With the first Speed 20, introduced in 1932, Alvis went wholeheartedly for exceptional performance allied to dashing, low-built coachwork. A new double-dropped chassis frame of 10'3" wheelbase lowered the whole car. Standard 4 door tourers were by Cross & Ellis, with the 4 door saloon from Charlesworth,but new London distributor Charles Follett offered a two door tourer, a two door sports saloon and a drophead coupé by van den Plas at greater cost. Maximum speed was 90 mph.


1932 SA Speed 20 van den Plas tourer

The chassis attracted other coachbuilders as a basis for small series or "one-off" production. Superficially the engine resembled previous designs, especially the 19.82 Silver Eagle, with its cast iron head and block bolted to a separate aluminium crankcase, but in fact very little was interchangeable and the mounting method was different, using bearers at the front and mounts under the gearbox at the rear. No longer was the engine used to add rigidity to the front of the chassis. It was a 6 cylinder of 73x100 mm, 2511 cc, with pushrod overhead valves, three SU carburettors and dual magneto/coil ignition. Output was 87 bhp.


1932 SA Speed 20 Mayfair saloon

A unit mounted centre change "crash" gearbox was used, in conjunction with a clutch stop to speed upward changes. Suspension was by conventional semi-elliptics all round. This was a car of a very sporting character, taught and responsive, albeit with a rather hard ride. The steering was outstanding and the brakes, with 14" drums, carried on from the Silver Eagle 20, stopped well provided the driver could push hard enough on the pedal. A handwheel protruding through the floor allowed the driver to adjust the brakes with the car in motion, a device of somewhat dubious value. Later versions of the Speed 20 were definitely "softer" and more luxurious in nature. Around 400 SA models were made.


1933 SA Speed 20 Bertelli tourer

Alvis engineers saw the need for greater refinement and more luxurious coachwork: from now on the proportion of cars with (originally) saloon or drophead bodywork became ever higher. The standard of roads was beginning to improve, albeit slowly, and driving speeds to increase. Motoring was being used for business and social purposes rather than as a pastime in its own right, and these factors combined to increase the proportion of buyers opting for closed, comfortable bodywork. The rear seats of an open car were a cold and breezy environment, unpleasant at anything above 40 mph. The later Speed Twenties reflected these developments; the emphasis changed from speed alone to speed with comfort, refinement and ease of control.


1934 SB Speed 20 van den Plas tourer

The SB 19.82 model introduced at the 1933 Motor Show used an engine practically identical to that of the SA, but in a new 10'4" wheelbase chassis. This featured independent front suspension similar to that introduced the previous year on the Crested Eagle, using a transverse leaf spring and wishbones. The steering linkage was complex, using twin drag links from a track rod mounted behind the engine. For the first time, Alvis fitted a proprietary clutch from Borg & Beck in place of their own unit, and all subsequent Alvis designs use units from this maker except for a few from the delightfully named Roper and Wreaks.


1934 SB Speed 20 van den Plas DHC

A completely new gearbox introduced synchromesh on all the forward ratios; this unit reverted to being mounted separately from the engine. The all-synchro box was a tremendous advance and made the car much easier to drive, with the considerable performance more accessible. Brakes remained much as on the SA, and built-in jacks eased wheel changing until they rusted up. The bonnet grew to considerable length on the SB, and this, combined with the low chassis, made it easy for the bodybuilders to achieve great elegance of line. Lucas P100 lamps were fitted as standard, with smaller pass lights below providing illumination on dipped beam. A front bumper formed part of the specification.


1935 SC Speed 20 Charlesworth saloon

Further improvements were made for the 1934 Motor Show; these appearing on the SC 19.82 model. An increase in stroke to 110 mm raised capacity to 2762 cc, without apparently increasing the bhp, but presumably with more torque to cope with the ever more luxurious bodies. Multiple "cluster" valve springs, 9 in a circle around each valve were used, 108 springs in all. This system continued until the war on the Speed 25, 3.5 and 4.3 Litre cars. The front suspension was improved in detail, particularly the damping, now by André Telecontrols with their attendant piping, pumps and dashboard gauges adding to the plethora of pipes for the lubrication system running around the chassis.


1935 SC Speed 20 Charlesworth DHC

At the same time the steering linkage was simplified somewhat and the chassis side members now ran both above and below the rear axle for extra strength. The bonnet on this model was not quite so long as on the SB.

Last of the Speed Twenties was the SD 19.82 introduced for the 1936 model year. A longer, 10'10" chassis was optional. Main changes were a wider scuttle and a revised fuel tank. Total IFS Speed 20 production was approximately 750 cars.


1936 SD Speed 20 Charlesworth saloon

1933 Alvis Speed 20 SB

dimensions & weights
Wheelbase 3124 mm 123 in  
Track front 1422 mm 56 in  
rear 1422 mm 56 in  
Length 4572 mm 180 in  
Width 1689 mm 66.5 in  
Kerb weight 1372 kg 3025 lb  
Type S-6
OHV
12 valves total
2 valves per cylinder
Bore × stroke 73.00mm × 100.00mm
2.87 in × 3.94 in
Bore/Stroke ratio 0.73
Displacement 2511 cc
(153.231 cu in)
Unitary capacity 418.5 cc/cylinder
Compression ratio 6.33:1
Fuel system 3 SU carbs
Aspiration Normal
Max. output 88.2 PS (87.0 bhp) (64.9 kW)
@4000 rpm
Max. torque
 
Coolant Water
Specific output 34.6 bhp/litre
0.57 bhp/cu in
performance
0-50mph (80 km/h) 13.50s
0-Quarter-mile 21.00s 
Top speed 143 km/h
Power-to-weight 63.41 bhp/ton
chassis
Engine location Front
Engine alignment Longitudinal
Drive RWD
Top gear ratio 1.00
Final drive ratio 4.55