1977 Mercedes-Benz C111-III

The success of the C111 and of the sparsely modified C 111-II in Nardo spurred the developers on to new heights. But it wasn’t enough. They wanted to break the 300 kmh barrier. For this to happen, the engineers knew that they had to “transform” the road-going version of the C111 into a “proper” racing car.

In 1977, the C111-III was built. The new car was designed in Sindelfingen under the direction of Prof. Hans Scherenberg. This car, which had little in common with C111-II, had a longer wheelbase, a narrower track, concealed wheels, a very low front end with recessed, powerful headlamps and a very long and tapering rear end with a central fin that was to enhance the car’s straight-line stability under side wind conditions. The aerodynamic features were refined down to the smallest detail giving the car a Cd = 0.183 (drag coefficient), the lowest rating ever achieved up to that point in time.

The long and narrow driver’s compartment featured a single seat: the front passenger’s space was occupied by a fat pipe conducting air into the intercooler. And there was also room for the telemetry system, specially developed by Mercedes-Benz for automatic data transmission during the record runs, as well as for radio equipment, enabling the driver to communicate with the team on the move.

A 5 cylinder, 2999 cc, OM 617A supercharged in-line Diesel engine, supported by a Garret intercooled exhaust gas turbocharger which, at 130,000 revolutions per minute, pressed enough air into the combustion chambers to boost the output to 230 hp (169 kW) / 4200-4600 rpm, growled under the silver-painted plastic bodywork. They were aiming for 200mph (320 kmh). In reality the C111- III achieved 202 mph (325 kmh). Because of its very “long” ratio, the car did take its time, however, to reach this speed (a complete 12.66 kilometer lap of the circuit in Nardo in southern Italy, to be precise).

Finally, on April 30, 1978, the time had come for the diesel-engined record car to drive lap after lap at constant speed on the Nardo track – anti-clockwise because this meant that the crash barriers were on the right-hand side, providing the drivers of the LHD cars (Left Hand Drive) with a greater safety margin in the event of an accident.

At one stage during the night, radio communication saved a hedgehog’s life: it was rescued in time before crossing the racing car’s lane. More drama ensued when the rear tire on the right-hand side burst during the third driver’s stint at night-time, tearing large holes into the bodywork. The recovery truck arrived on the scene quickly to pick up the damaged car and its uninjured driver, while the mechanics prepared the identical reserve car. After this incident, clocks were reset to zero and the hunt for records began anew.

The reserve car was even a whisker faster than the original car, and also a little more economical, extending the refueling intervals from 62 to 67 laps. The three drivers were soon joined and relieved by their extremely fast project manager, Dr. Hans Liebold.

All records established by the time of the tire damage were repeated at even better times, and the attempt was not even jeopardized by another hedgehog which was unfortunate enough to get in the record car’s way and ruined its front spoiler. The repair took no more than two minutes. The pit stops, incidentally, lasted between 15 and 20 seconds – the refueling, driver changes; tire checks and topping up of oil had all been meticulously planned and thoroughly practiced.

After 12 hours of otherwise problem-free driving, the Mercedes-Benz brand called nine new absolute world records its own, irrespective of the type of engine and its displacement – achieved with a near-production three-liter diesel engine. At the end of the day, the engine in the record car had consumed just less than 16 liters per 100 kilometers – another outstanding record given an average speed of over 300 km/h.

The world records established by the diesel-engined C111-III:

100 km – 316.484 km/h  (196.654 mph)

500 km – 321.860 km/h  (199.994 mph)

1000 km – 318.308 km/h  (197.787 mph)

100 miles – 319.835 km/h  (198.736 mph)

500 miles – 320.788 km/h  (199.328 mph)

1000 miles – 319.091 km/h  (198.273 mph)

1 hour: 321.843 km/h  (199.983 mph )

6 hours: 317.976 km/h  (197.581 mph)

12 hours: 314.463 km/h  (195.398 mph)

TECHNICAL DATA SPECIFICATIONS

Engine type OM 617 LA
Inlet valves 1 overhead valve per cylinder, actuated via finger follower
Ignition sequence 1-2-4-5-3
No. of cylinders / arrangement 5 / in line
Outlet valves 1 overhead valve per cylinder, actuated via finger follower
Configuration In front of rear axle, longitudinal; vertical
Valve operation 1 overhead camshaft, double roller chain drive
Combustion principle Four-stroke Diesel (with indirect injection, Garrett turbocharger, charge air cooling)
Crankshaft 6-bearing
Bore x Stroke 90.9 x 92.4 mm
Fuel system Indirect injection, Bosch 5-plunger injection pump
Total displacement 2999 cc
Spark plugs 1 glow plug per cylinder

Fuel supply Bosch piston pump as part of the injection pump
Compression ratio 17.5
Fuel tank capacity 140 l
Maximum / output / rated output 230 hp at 4200-4600 /min
Rated torque 403 Nm at 3700 /min

Cooling Water circulation cooling
Lubrication Pressure circulation lubrication
Cylinders Gray cast iron block
Cylinder head Light alloy, removable
Starter Electrical, Bosch
Ignition Compression ignition

Foot brake Acting on front- and rear wheels
Steering Recirculating-ball steering
Wheels Light-alloy wheels
Front tires 230/600 x 15 Dunlop
Frame design Structural floor assembly, welded sheet steel
Rear tires 230/600 x 15 Dunlop

Front wheel suspension Double wishbone, suspension struts, torsion bar stabilizer

Drivetrain Direct transmission from engine-transaxle unit to rear wheels
Rear wheel suspension 3 wishbones and 2 trailing arms per wheel, suspension struts, torsion bar stabilizer

Brake system Hydraulically actuated dual-circuit brake system
Front brakes Internally ventilated disc brakes
Rear brakes Internally ventilated disc brakes

Transmission ZF 5-speed manual transmission in unit with differential gear, mounted behind rear axle
Shifting Center shift
Clutch Dry double-disc clutch
Transmission type Change-speed gear
Gear ratios Overall ratio in 5th gear: 1.65
Maximum speed 325 km/h

Dimensions and Weights
Wheelbase 2720 mm
Front track 1260 mm
Rear track 1320 mm
Length 5380 mm
Width 1715 mm
Height 1045 mm
Vehicle weight 1400 kg
Comments Drag coefficient = 0.183
Engine weight 244 kg
Seats 1