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- Melbourne, Australia
Following the victory in the 1908 French Grand Prix, Mercedes suspended the company's competition program. Instead, the Paul Daimler-led engineering team focused on the development of aero engines. During this period valuable lessons were learned about light weight materials and construction. These were applied when the German manufacturer decided to ready brand new cars for the 1914 French Grand Prix at Lyon.
Considering the new-for-1914 displacement limit of 4.5 litres and maximum weight of 1100 kg, Mercedes figured a four cylinder engine would suffice. In Mercedes' absence, Peugeot had come to the fore with hugely sophisticated twin-cam, four valve per cylinder engines. These cutting edge machines had taken victories in the 1912 and 1913 French Grand Prix and were certainly the cars to beat in 1914.
Using aero engine technology, a brand new straight four was developed. It was built on an aluminium crankcase with separate steel cylinders. Welded on the cylinders, the individual heads sported four valves. Keen to do things their own way, Mercedes used just a single overhead camshaft to actuate the valves. The camshaft was driven from the crankshaft by a shaft that was fitted at the rear of the engine. The crankshaft itself was counterbalanced and was forged in the highest grade of Austrian steel.
Designed to run at twice the speed of any Mercedes engine that had come before, lubrication of the new 'four' was vital. An intricate system was fitted that combined a wet sump with a high pressure pump. No piston rings were fitted so, by the design, the engine used oil. Additional oil could be fed into the system by a manual pump, to be operated by the riding mechanic. To prevent the plugs from fouling, up to four plugs could be fitted, although the cars raced with three. With an eye on reliability these were powered by two separate magnetos.
The 'M 93654' engine was fed by a single Mercedes up-draught carburettor. The first competition engine to rev over 3,000 rpm, the 'four' produced it's peak power of 106 bhp @ 3,100 rpm. This was quite an achievement considering no other Mercedes/Daimler engine built up to that point could safely rev over 1,500 rpm. A separately mounted four speed gearbox was used. This was connected to the rear wheels not through the chain previously used but by a propellor shaft for weight saving reasons.
The chassis of the new Grand Prix racer followed convention with a cross-braced, pressed steel frame suspended by semi-elliptic leaf springs and solid axles. One of the things carried over from the 1913 experimental cars was the V-shaped radiator and lightly wrapped aluminium body complete with belly pan. To reduce drag even further, even the front axles were 'streamlined'. Unlike most of the rivals the Mercedes '18/100' only featured brakes on the rear axle and an additional transmission brake.
Touted as the most important race yet, the entrants of the French GP not only represented the respective manufacturers but also their countries of origin. Considering the political tension that was quickly building around Europe, the nationalistic feelings reached boiling points. Mercedes entered five cars and in addition to three Peugeots further high level entries were fielded by Fiat, Opel and Sunbeam. Among the Mercedes drivers was the company test pilot Christian Lautenschlager, who had surprisingly won the 1908 Grand Prix for Mercedes.
Mercedes' Max Sailer took an early lead in the race but his 18/100 only lasted six of the planned twenty laps. In his wake Peugeot lead driver Georges Bouillot have chase but his style and front brakes required additional tyre changes. The very efficient Mercedes was much kinder non it's tyres and required only two sets of tyres for the entire race. Already passed by Lautenschlager, Bouillot's Peugeot failed on the final lap. This freed the way for a spectacular 1-2-3 victory for the new Mercedes. Lautenschlager was once again the winner, leading Louis Wagner and Otto Salzer home. The fifth Mercedes had retired early with gearbox problems.
Shortly after the French GP, war spread across the continent and all racing was suspended. One of the cars had been rushed out of the country for Ralph DePalma to race in the United States. He did so with great verve, winning several races, including the 1915 Indy 500. Pressed for money, Mercedes sold several of the other Grand Prix racers to privateers after the War. Constantly updated by their owners, these were raced with great success until the late 1920's. Among the many victories scored was an outright win in the Targa Florio in the hands of Giulio Masetti.
With wins in the French GP, the Indy 500 and the Targa Florio, the 1914 Mercedes 18/100 ranks among the finest racing cars ever built. Of the six examples built, at least three are known to have survived.
ENGINE
Configuration
Water cooled, M93654, Straight four
Location
Front, longitudinally mounted
Construction
Steel block and head
Displacement
4483 cc / 273.6 cu in
Bore / Stroke
93 mm (3.7") x 165 mm (6.5")
Compression
5.4:1
Valvetrain
4 valves per cylinder, SOHC
Fuel feed
Mercedes carburettor
Ignition
Triple spark
Lubrication
Wet sump
Aspiration
Naturally Aspirated
Power
105 bhp / 78 kW @ 3100 rpm
Torque
283 Nm / 209 ft lbs @ 2000 rpm
Redline
3200 rpm
DRIVETRAIN
Body
Aluminium panels and belly pan
Chassis
Pressed steel ladder frame with cross-member
Front suspension
Solid axle, semi-elliptic leaf springs, friction dampers
Rear suspension
Live axle, semi-elliptic leaf springs, friction dampers
Steering
Worm and nut
Brakes
Rear drum brakes
Gearbox
4 speed manual
Ratios
3.00:1, 1.50:1, 1.20:1, 1.00:1
Top speed
185 km/h
DIMENSIONS
Weight
1082 kg / 2385.4 lbs
Length
4100 mm / 161.4"
Width
1700 mm / 66.9"
Height
1400 mm / 55.1"
Wheelbase
2845 mm / 112"
Front track
1330 mm / 52.4"
Rear track
1350 mm / 53.1"
http://www.conceptcarz.com/z20369/Mercedes-Benz-115HP.aspx
http://www.roadandtrack.com/motorsp.../?mag=rdt&list=nl_rdt_news&src=nl&date=091115
http://www.supercars.net/cars/1187.html
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