THE ULTIMATE SILVER ARROW
the next level wouldn’t just be a wasted
opportunity, it would be a compromise – and
compromise was something the Mercedes-Benz racing department didn’t deal in.
Yes, the W154’s chassis would be based
on the W125’s sturdy tubeframe design,
but that was by choice, not expediency.
Proving that it’s not just modern grand
prix teams that possess the manpower
and resources to work on current and
future designs concurrently, preliminary
design on the W154 began in early 1937,
in parallel with development of the W125.
With the new-for-’ 38 3-liter engine
barely half the capacity of the M125, Heess
knew 600hp was out of the question. But
with the goal of increasing power per liter
by 50 percent, he’d still set his sights high.
Options considered, but quickly
discarded, for the W154’s engine and
basic layout included a naturally aspirated,
direct-injection W24 (three banks of eight
cylinders) mounted in the rear, a la Auto
Union, with a streamlined “teardrop” body.
A 4.5-liter inline- 8 was also mooted,
but the chosen solution was a front-mounted, twin-supercharger, 3-liter,
60-degree V12, the M154. For cooling,
each block of three cylinders had its own
welded steel-plate cooling jacket, while
engine oil flow was 100 liters per minute.
Bench testing of the engine began Jan.
1938. Heess initially chose to run with fuel
injection, but settled for twin carburetors
Configuration front-engine, rear-wheel drive,
open-wheel, single-seat prototype
Category Grand Prix
Championship AIACR European
Championship (1938 and ’ 39)
Engine Mercedes-Benz M163 (superseding
1938-spec M154); longitudinally-mounted,
2,962cc, 60-degree V12 w/double overhead
camshafts; two-stage Roots-type supercharger
(superseding twin superchargers on M154)
Engine weight 558lbs/253kg
Power/torque 483hp 7,800rpm;
Transmission Mercedes-Benz 5-speed
manual transmission w/ZF differential
Chassis Nickel-chrome molybdenum oval
tube frame w/aluminum bodywork
Brakes Hydraulic drum
Front suspension Independent w/double
wishbones, coil springs and hydraulic
Rear suspension De Dion axle, longitudinal
torsion bars, and driver-adjustable hydraulic
TECHNICAL SPECIFICATIONS (1939)
Tilting the W154’s supercharged, 3-liter,
60-degree V12 engine allowed for a lower
center of gravity and a reduced frontal
area, meaning less drag. The driver sat
low and to the left of the offset driveshaft.