primotipo…

Donald Healey in his supercharged Austin Healey 100S ‘Streamliner’ at Bonneville in November 1954…

Late in 1954 Healey’s introduced the 100S, its power output was up to 132 bhp over the standard 100’s 90 bhp. A four speed gearbox was fitted, suspension modified and Dunlop disc brakes installed to all four corners of the attractive car. Reshaped panels in aluminium both made the car lighter and slipperier.

What better way to promote sales of the marque generally and of the 100S specifically than a further spot of record breaking?- hence the construction of the Shorrock supercharged car with its swoopy body designed by Gerry Coker.

The top speed the car achieved in Donald Healey’s hands was 192.6 mph, whilst on the Bonneville Ten Mile Circuit Carroll Shelby took further records including the 25-200 kilometres plus the one hour mark at 157.92 mph.

The Healey team considered building a special car but time did not permit so a standard BN1 body/chassis unit was used to which was added a new nose and tail and bubble-type perspex cockpit cover. The workmanship of the snout and body were reported as being exemplary.

The mods were determined after wind tunnel tests on a scale model by Sir WG Armstrong of Whitworth Aircraft Ltd. ‘The Motor’ reported that the completed car was later tested in Austin’s full-scale ‘tunnel- the technician’s estimate of the machines top speed was only 0.6 mph shot of Healey’s best effort. Who needs computers?!

In terms of the engine, prepared by Dr JH Weaving of BMC Gas Turbine Research, the 100S had in standard form a nitrided crank running in trimetal bearings and ‘the special cylinder head with enlarged valves and special porting which are the outstanding features of the new unit’.

Changes from the standard S engine included lapping the head to the block to avoid head gasket problems, the water flow also was slightly modified. A stock Shorrock C250B supercharger was coupled direct to the nose of the crank by two ‘Layrub’ couplings- maximum boost was about 8 psi. A special radiator core was used and a Tecalemit combined oil filter/cooler was incorporated. The engine produced 224 bhp @ 4500 rpm whereas the standard 100S was quoted at 132 bhp @ 4700 rpm.

The Motor advised a ‘special’ five speed gearbox was fitted with overdrive which gave a top gear ratio of 2.2:1 with the standard 16 inch Dunlop disc wheels fitted.

So slippery was the Streamliner that it ran for six miles (!) when the engine was cut at 180 mph.

Safety features included an onboard Graviner fire extinguisher system which was directed at both the engine bay and boot where the 25 gallon fuel tank was located- both impact and driver operated switches were installed. A ‘crash arch’ was behind the driver, two levers allowed the Perspex screen to be jettisoned, a switch in the lubrication system shut off the fuel supply if oil pressure fell below a set level. Donald found the standard steering wheel interfered with his vision so a rectangular one was made.

When completed the Streamliner was tested at an airfield circuit by Geoffrey Healey to speeds of about 130 mph before shipment to the US.

Healey did the straight line runs at Bonneville raising the International Class D Records for 5 Km 182.2 mph, 5 miles 183.87 mph, 10 Km 183.8 mph and 10 miles 181 mph. The 192.6 mph measured kilometre time was an American national record but not a world mark- it was held by a Mercedes at 248.3 mph, a time set by Rudy Caracciola in 1939 on the eve of the War. The Healey on one run did better 200 mph.

Carroll Shelby then took over the wheel on the 10 mile circle course and set an International Class D Record for the hour at 156.7 mph.

Donald Healey achieved the 200 mph mark he sought in 1956 using the same BN1 Streamliner chassis (SPL227B) in which he was successful in 1954 but fitted with a supercharged C-Series engine which in normally aspirated form was soon to be fitted to the new 100-6.

Bill Leyland modified the engine at Austin’s to produce 292 bhp @ 5000 rpm. Wind tunnel work and the advice of Dr John Weaving resulted in the removal of the cars tail-fin, Geoff Healey thought this ruined the look of the car but stability was aided- Austin engineers estimated a top speed of 217 mph.

 

The removal of the tail fin is interesting as it was commented favourably upon in ‘The Motor’ report of the 1954 successes on the 10 Mile course ‘The car proved very stable, which was indeed fortunate, for conditions were by no means ideal, gusts of wind up to 30 mph sweeping across the Salt Flats.’

‘Moreover owing to the complete absence of trees or any other vegetation, the driver receives no advance warning of a gust before it strikes the car. The tail fin proved of real value in such circumstances, the general opinion being that it would even have been more helpful if it had been made larger.’

Whatever the case, the car ran sans tail-fin in 1956.

Healey tested the car at Bonneville on 9 August and after repairing a sheared supercharger drive took it out on 21 August, his two way average speed was 201.10 mph, Donald was the nineteenth person to exceed 200 mph.

The Healey Team Bonneville 1956 trip included another very sexy machine.

‘The Endurance Car’ was a long-nosed BN2 fitted with a six-port head to which three Weber 40DCOE carburettors were attached.

The Eddie Maher prepared, standard capacity 2639 cc, OHV six cylinder engine produced 164 bhp @ 5500 rpm burning a mix of one third each methanol, benzole and petrol using a compression ratio of 10.2:1.

The very swoopy, curvaceous body was designed and constructed by Jensen Cars- a mighty fine job they did too.

Testing of this car on 9 August revealed vapour lock problems which were solved and continued on the 14th where a misfire diagnosed as due to lack of compression on #1 cylinder due to a poorly seated inlet valve occurred.

All of the valves were replaced but it was discovered that the water passages did not line up. The gasket was predicted to have a short life so runs on the Ten Mile Circuit started early in the cool of the day, the driving chores shared by Carroll Shelby and Roy Jackson-Moore.

The car kept going for six hours before the gasket failed, long enough to capture International Class D records for 200 miles, 500 Km, 500 miles, 1000 Km, 3 hours and 6 hours at speeds of between 145.96 mph (6 hours) and 153.14 mph (500 miles).

The endurance car was Healey Blue and White and featured the oval grille and horizontal bars that were soon introduced on the 100-Six in September 1956, Healey being a believer on the win on Sunday sell on Monday dictum…

Carroll Shelby, Roy Jackson-Moore and Donald Healey beside the Endurance Car with the Streamliner in supercharged six-cylinder guise behind at Bonneville immediately after the successful record attempts in August 1956.

Etcetera…

Carroll Shelby beside the BN1 100-6 modified engine Endurance Car in August 1956. Isn’t it just a lovely looking thing sans bumpers with head-fairing and the Dunlop disc wheels?

 

 

Stirling Moss at the wheel of the BN1 100-6 modified engine Endurance Car during practice over the 1956 Nassau Speed week. He tested the car, but did not race it, winning the Nassau Trophy in a Maserati 300S.

 

Arcane and Irrelevant…

I’d never heard of a Layrub Joint so I figure some of you other non-engineering types may be equivalently ignorant as my good self.

This little jobbie, originally developed by the Laycock Company, is a number of moulded rubber blocks with specially shaped cavities at their ends sandwiched between two steel pressings. Each shaft is connected by means of a fork to alternate rubber blocks.

The construction of the device allows the rubber blocks to deform and drive to be transmitted through a small angle, small axial and angular movements for shaft length alteration can be accommodated as well as torsional damping.

So, there you have it!

Credits…

Getty Images, http://www.healeysix.net, ‘The Motor’ November 1954, ‘Hillier’s Fundamentals of Motor Vehicle Technology’ Victor Hillier and Peter Coombes

Tailpiece: Donald Healey, AH 100S Streamliner November 1954…

You can just see the perspex screen over Healey’s head as he drives beside the line.

Finito…