mika
Still Wondering
Happy Birthday
BMW PressClub puts out historical pieces periodically. While we were in West Bend last year BMW was celebrating ninety years. Here is PART III of three parts on the history of the company.
Ninety Years of BMW –
the Symbol of Innovation.
PART I. BMW Aircraft Engines.
PART II. BMW Motorcycles.
PART III. BMW Cars.
Ninety Years of BMW –
the Symbol of Innovation.
The spirit of innovation has transcended through the history of BMW for no
less than 90 years. And indeed, this ongoing innovation of the white-and-blue
brand has been borne out and initiated consistently by the creativity, skill,
and consistency of the company’s employees. The products created in this
process have at all times combined proven and new technologies in a
most characteristic manner, forming a sophisticated, trendsetting symbiosis
at all times.
PART III. BMW Cars.
Purchasing Fahrzeugfabrik Eisenach, the Eisenach Vehicle Manufacturing
Plant, in 1928, BMW established a third pillar for the company in addition to
the production of aircraft engines and motorcycles: the production of cars.
For reasons of time and to avoid any undue risks in the new market, the company
started out by continuing licence production of the Austin Seven which
began in Eisenach in 1927 under the model designation 3/15 PS DA 2.
Four years later BMW’s engineers had gained sufficient experience with their
new four-wheel products to introduce the first car into the market developed
by BMW itself, the BMW 3/20 PS. And indeed, this new model was full of
innovations right from the start, featuring a central box frame and independent
wheel suspension both front and rear, and thus offering a driving experience
customers had previously only been able to enjoy in far larger and more
luxurious cars.
Within just one year, the BMW 3/20 PS was available to customers not only
as a new car, but also with a new power unit, the new, 20-hp 782-cc engine
featuring overhead hanging valves and running much more quietly than its
predecessor. The seats, motoring comfort and lines of the new car were also
far more harmonious and modern than on its rather spartan predecessor.
The BMW 303: the first six-cylinder.
In 1933 BMW moved up to the highest realms of technology also in the
automobile market: Introducing the BMW 303, the company proudly unveiled
its second “home-made” car and the first BMW to feature the kidney radiator
grille. Within the engine compartment the new model boasted a 1.2-litre
six-cylinder in-line engine developing maximum output of 30 hp. The most
outstanding forte of the new car, however, was its excellent driving
and motoring qualities quite unprecedented in this part of the market.
BMW had opted for this power unit code-named the M78 after two former
designs appeared either too sophisticated or too primitive. The engine was
based on a four-cylinder introduced a year before and differed primarily
through the combination of the crankcase and cylinder block to form one
complete unit.
Further highlights were the camshaft fitted beneath the engine block and the
tappets operating the valves in vertical, hanging arrangement via rocker arms.
Both the intake and exhaust pipes were on the same side.
A feature quite unusual today was the varying gaps between cylinders:
The distance between the second and third, and the fourth and fifth, cylinder
were larger than the other gaps between the cylinders, with this extra
space being required to accommodate the crankshaft and camshaft bearings.
The crankshaft not using any counterweights therefore ran in four bearings,
just like the camshaft.
This was however not the main reason for this rather distinctive design.
Rather, the crucial factor was that back then the crankshaft was assembled
together with the connecting rods and pistons as one completely prefabricated
unit. And since the pistons thus had to be fitted into position from
below, the main bearing supports for the crankshaft were not allowed to
extend into the cylinder contours. Hence, the only option was to
accommodate the main bearings between cylinders further apart from one
another.
Highly inventive: using the exhaust gas to heat up the carburettors.
A similarly unusual feature from today’s perspective, but nevertheless quite
characteristic of BMW’s typical inventiveness, was to be found in the fuel
supply system, where the intake manifolds were enclosed by six-centimetrewide
chambers directly above the two updraught carburettors. Using the
heat from the exhaust system, these chambers served to warm up the fuel/air
mixture, eliminating the risk of icing and improving the distribution of the
air/fuel mixture.
In the years to come this engine served as the foundation for developing a
number of further six-cylinders, some of them even with an aluminium cylinder
head. Engine capacity was increased to two litres, and depending on power
requirements either one, two or three carburettors delivered the fuel/air mixture
to the combustion chambers.
Such a three-carburettor engine developing 40 hp was to be found in the
BMW 315/1, a light sports two-seater launched in 1934 and scoring a wide
range of success in numerous races and other contests. Indeed,
the sporting character of BMW cars began with this very engine and in this
particular model.
][bThe BMW 326: frame and body welded to form one unit.[/b]
Two years later, BMW launched a new top-range model immediately
acknowledged as one of the most advanced large-scale production cars of its
time: the BMW 326. This was in fact the first BMW featuring a bodyshell
welded to the frame, doors hinged at the front, a hydraulic brake system and
the spare wheel beneath a cover on top.
Proceeding from a newly developed low-bed box frame with a torsion barsuspended,
low noise rear axle, as well as transverse-leaf springs on the front
axle moved further down, BMW’s engineers had created an all-new midrange
model. The engine was also a new two-litre six-cylinder with two carburettors
and maximum output of 50 hp conveyed to the wheels by a partly
synchronised four-speed transmission even featuring a free-wheel function in
first and second gear. Top speed of the BMW 326 was an impressive
115 km/h or 71 mph.
The 326 was not to remain BMW’s only sensation in the year 1936. For the
next highlight appeared at N??rburgring on 14 June, when the brand-new
BMW 328 made its first appearance. This superior sports car was indeed the
result of a very fast development process, since the engineers, designers
and mechanics in BMW’s Development Division in Munich had had only little
time and money to make this thoroughbred sports car reality.
But while being forced to restrict themselves to the essential, BMW’s
specialists still had all their creativity to offer – and they were extremely
successful in bringing this creativity to bear: Within a short time, the new
BMW 328 dominated its category in motorsport, quite often leaving even far
more powerful competitors far behind. And this is understandable,
considering that 80 horsepower in the regular production version weighing just
830 kg or 1,830 lb overall gave this elegant roadster truly impressive power
and performance – and still does so today.
Elegant lightweight construction: the BMW 328 Mille Miglia.
BMW entered the 1940 Mille Miglia with unique roadster and coup?® models
built by Carrozzeria Touring in Milan. The thin aluminium skin on these
Superleggera bodies was mounted directly on the filigree, load-bearing tubular
spaceframe made of steel, reducing overall weight of the coup?® in road trim
to just 780 kg or 1,720 lb and allowing a top speed of 220 km/h or 136 mph.
The power unit featured in this legendary sports car was BMW’s first
automobile engine with V-shaped hanging valves operated not by overhead
camshafts, but rather by thrust rods and rocker arms. And since the
engine block featured thrust rod guides only on the intake side, a mechanism
in the cylinder head conveyed the operating forces via pivot bars and levers
to the opposite side of the engine.
A revolutionary test: the BMW 328 with fuel injection.
Featuring three downdraught carburettors fitted on the cylinder head,
the two-litre six-cylinder developed 80 hp in regular trim, accelerating the
lightweight BMW 328 to a top speed of more than 155 km/h or 96 mph
and soon becoming the very epitome of the sports engine.
But this was far from the end of the road for the six-cylinder, with engine output
being increased to 100 and even 110 hp on competition engines. The limit
in the process was set not so much by the engine as such, but rather by the
availability of fuel restricted to just 80 octane. This, in turn, limited the
compression ratio to a maximum of 9.5 : 1, in order to avoid the risk of the
pistons burning through. So it was only the introduction of special racing
fuel that enabled BMW’s engineers to overcome this limitation, increasing
output of the BMW 328 all the way to 136 hp. And in 1941 BMW’s
engineers even conducted tests with fuel injection on this outstanding engine,
using three throttle butterflies instead of the conventional carburettors.
The BMW 501: the “Baroque Angel” full of highlights in technology.
Losing the Eisenach Car Production Plant in the War, BMW found it difficult
to make a new start in the post-war years. Hence, the first new model did not
appear until the 1951 Frankfurt Motor Show – the BMW 501.
Although relatively “classic” in its design and styling, the “Baroque Angel”
was full of highlights in technology: The two half-shafts at the front were each
mounted on two triangular track control arms running in needle bearings.
This low-friction bearing technology ensured a particularly sensitive response
on the part of the progressive springs and suspension made up on each side
of a longitudinally arranged, extra-long torsion bar.
The arrangement of the dampers was likewise quite unusual: Fitted at the
outside on the lower triangular arms, the dampers extended upwards
in an inclined position, coming to rest inside on the upper track control arm.
This avoided any contact with the sprung body and prevented even the
slightest transmission of noise.
Focusing on the steering, the engineers in Munich introduced a very special
idea on the BMW 501, applying the principle of rack-and-pinion steering
to a crown wheel segment in the interest of maximum steering precision.
The oil reservoir for the steering served at the same time to lubricate all other
front axle components, which therefore remained independent of the
regular central lubrication. The rear axle, as all testers agreed at the time, was
the “ultimate level of perfection in the development of the live axle”,
torsion bars acting on the axle right at the outside via spring arms serving here,
too, to provide the necessary suspension effect and at the same time
giving the car its longitudinal guidance.
Even the gearbox with gears being shifted straight from the steering wheel
was arranged in a different position: Instead of being bolted directly to the
engine, the gearbox with its four all-synchromesh gears was housed beneath
the front seats and connected to the engine by a short propeller shaft.
The advantage of this particular arrangement was that the footwells remained
largely free, without being impaired or cluttered by a voluminous transmission
housing. A further benefit was that the engine mounts did not have to be
re-designed for maximum torque from the transmission, meaning that the
engine was able to rest on unusually soft and smooth mounts. The bottom
line, therefore, was that the 65-hp six-cylinder, a modified version of the
engine already featured in the BMW 326, was exceptionally smooth and
refined in the BMW 501.
1954: introduction of the world’s first light-alloy eight-cylinder.
The BMW 501 nevertheless only paved the way for BMW’s most spectacular
innovation in the ’50s: The first series-production light-alloy engine in the
world and the first German eight-cylinder after the end of the War launched in
1954. Weighing in at 210 kg/463 lb, the 2.6-litre power unit in the BMW 502
was just 28 kg or 62 lb heavier than the six-cylinder in the 501.
The pistons with four rings ran in “wet” cylinder liners, that is centrifugal-cast
liners surrounded by coolant pipes.
This solution was the obvious choice right from the start because BMW
planned from the beginning to build not just the 2.6-litre with its almost square
combustion chambers, but also a 3.2-litre with exactly the same stroke but
longer bore.
The oil pump on the smaller engine was driven by a divider shaft, the oil
pump on the larger engine by a roller chain. Otherwise the higher delivery
output of the pump might have overburdened the sensitive gearwheels.
The intelligent method used to fasten the rocker arm shafts in position once
again bore testimony to the inventiveness of BMW’s engineers, with the
inner support bolts on the bearing blocks, like the pushrods, being made of
special dura-steel and extending through the entire cylinder head all the
way to the housing at the back. As a result, the support bolts maintained the
same consistent distance to the crankcase also in the transition from cold
to high temperatures, even though the different metals warmed up at a varying
rate. The result was excellent valve play compensation between cold
and warm running conditions. BMW’s advertising experts understandably
highlighted this construction at the time as “automatic valve play
compensation”.
The valves themselves were positioned parallel to one another at a 12?? angle
to the axis of the cylinders. And so while this was not a crossflow cylinder head
of modern design where the valves hanging in V-arrangement are positioned
opposite one another, this configuration helped to save space, which was
rather limited within the engine compartment of the BMW 502.
To keep the warm-up period as short as possible, the eight-cylinder
featured an oil-guiding corrugated pipe within its water shell serving as a heat
exchanger: After the engine was started cold this configuration was able to
warm up the coolant more quickly to its regular operating temperature, while
when driving fast it helped to cool the oil.
Displacing 2.6 litres, the V8 with double downdraught carburettors developed
maximum output of 100 hp when it made its debut into the market.
continued
BMW PressClub puts out historical pieces periodically. While we were in West Bend last year BMW was celebrating ninety years. Here is PART III of three parts on the history of the company.
Ninety Years of BMW –
the Symbol of Innovation.
PART I. BMW Aircraft Engines.
PART II. BMW Motorcycles.
PART III. BMW Cars.
Ninety Years of BMW –
the Symbol of Innovation.
The spirit of innovation has transcended through the history of BMW for no
less than 90 years. And indeed, this ongoing innovation of the white-and-blue
brand has been borne out and initiated consistently by the creativity, skill,
and consistency of the company’s employees. The products created in this
process have at all times combined proven and new technologies in a
most characteristic manner, forming a sophisticated, trendsetting symbiosis
at all times.
PART III. BMW Cars.
Purchasing Fahrzeugfabrik Eisenach, the Eisenach Vehicle Manufacturing
Plant, in 1928, BMW established a third pillar for the company in addition to
the production of aircraft engines and motorcycles: the production of cars.
For reasons of time and to avoid any undue risks in the new market, the company
started out by continuing licence production of the Austin Seven which
began in Eisenach in 1927 under the model designation 3/15 PS DA 2.
Four years later BMW’s engineers had gained sufficient experience with their
new four-wheel products to introduce the first car into the market developed
by BMW itself, the BMW 3/20 PS. And indeed, this new model was full of
innovations right from the start, featuring a central box frame and independent
wheel suspension both front and rear, and thus offering a driving experience
customers had previously only been able to enjoy in far larger and more
luxurious cars.
Within just one year, the BMW 3/20 PS was available to customers not only
as a new car, but also with a new power unit, the new, 20-hp 782-cc engine
featuring overhead hanging valves and running much more quietly than its
predecessor. The seats, motoring comfort and lines of the new car were also
far more harmonious and modern than on its rather spartan predecessor.
The BMW 303: the first six-cylinder.
In 1933 BMW moved up to the highest realms of technology also in the
automobile market: Introducing the BMW 303, the company proudly unveiled
its second “home-made” car and the first BMW to feature the kidney radiator
grille. Within the engine compartment the new model boasted a 1.2-litre
six-cylinder in-line engine developing maximum output of 30 hp. The most
outstanding forte of the new car, however, was its excellent driving
and motoring qualities quite unprecedented in this part of the market.
BMW had opted for this power unit code-named the M78 after two former
designs appeared either too sophisticated or too primitive. The engine was
based on a four-cylinder introduced a year before and differed primarily
through the combination of the crankcase and cylinder block to form one
complete unit.
Further highlights were the camshaft fitted beneath the engine block and the
tappets operating the valves in vertical, hanging arrangement via rocker arms.
Both the intake and exhaust pipes were on the same side.
A feature quite unusual today was the varying gaps between cylinders:
The distance between the second and third, and the fourth and fifth, cylinder
were larger than the other gaps between the cylinders, with this extra
space being required to accommodate the crankshaft and camshaft bearings.
The crankshaft not using any counterweights therefore ran in four bearings,
just like the camshaft.
This was however not the main reason for this rather distinctive design.
Rather, the crucial factor was that back then the crankshaft was assembled
together with the connecting rods and pistons as one completely prefabricated
unit. And since the pistons thus had to be fitted into position from
below, the main bearing supports for the crankshaft were not allowed to
extend into the cylinder contours. Hence, the only option was to
accommodate the main bearings between cylinders further apart from one
another.
Highly inventive: using the exhaust gas to heat up the carburettors.
A similarly unusual feature from today’s perspective, but nevertheless quite
characteristic of BMW’s typical inventiveness, was to be found in the fuel
supply system, where the intake manifolds were enclosed by six-centimetrewide
chambers directly above the two updraught carburettors. Using the
heat from the exhaust system, these chambers served to warm up the fuel/air
mixture, eliminating the risk of icing and improving the distribution of the
air/fuel mixture.
In the years to come this engine served as the foundation for developing a
number of further six-cylinders, some of them even with an aluminium cylinder
head. Engine capacity was increased to two litres, and depending on power
requirements either one, two or three carburettors delivered the fuel/air mixture
to the combustion chambers.
Such a three-carburettor engine developing 40 hp was to be found in the
BMW 315/1, a light sports two-seater launched in 1934 and scoring a wide
range of success in numerous races and other contests. Indeed,
the sporting character of BMW cars began with this very engine and in this
particular model.
][bThe BMW 326: frame and body welded to form one unit.[/b]
Two years later, BMW launched a new top-range model immediately
acknowledged as one of the most advanced large-scale production cars of its
time: the BMW 326. This was in fact the first BMW featuring a bodyshell
welded to the frame, doors hinged at the front, a hydraulic brake system and
the spare wheel beneath a cover on top.
Proceeding from a newly developed low-bed box frame with a torsion barsuspended,
low noise rear axle, as well as transverse-leaf springs on the front
axle moved further down, BMW’s engineers had created an all-new midrange
model. The engine was also a new two-litre six-cylinder with two carburettors
and maximum output of 50 hp conveyed to the wheels by a partly
synchronised four-speed transmission even featuring a free-wheel function in
first and second gear. Top speed of the BMW 326 was an impressive
115 km/h or 71 mph.
The 326 was not to remain BMW’s only sensation in the year 1936. For the
next highlight appeared at N??rburgring on 14 June, when the brand-new
BMW 328 made its first appearance. This superior sports car was indeed the
result of a very fast development process, since the engineers, designers
and mechanics in BMW’s Development Division in Munich had had only little
time and money to make this thoroughbred sports car reality.
But while being forced to restrict themselves to the essential, BMW’s
specialists still had all their creativity to offer – and they were extremely
successful in bringing this creativity to bear: Within a short time, the new
BMW 328 dominated its category in motorsport, quite often leaving even far
more powerful competitors far behind. And this is understandable,
considering that 80 horsepower in the regular production version weighing just
830 kg or 1,830 lb overall gave this elegant roadster truly impressive power
and performance – and still does so today.
Elegant lightweight construction: the BMW 328 Mille Miglia.
BMW entered the 1940 Mille Miglia with unique roadster and coup?® models
built by Carrozzeria Touring in Milan. The thin aluminium skin on these
Superleggera bodies was mounted directly on the filigree, load-bearing tubular
spaceframe made of steel, reducing overall weight of the coup?® in road trim
to just 780 kg or 1,720 lb and allowing a top speed of 220 km/h or 136 mph.
The power unit featured in this legendary sports car was BMW’s first
automobile engine with V-shaped hanging valves operated not by overhead
camshafts, but rather by thrust rods and rocker arms. And since the
engine block featured thrust rod guides only on the intake side, a mechanism
in the cylinder head conveyed the operating forces via pivot bars and levers
to the opposite side of the engine.
A revolutionary test: the BMW 328 with fuel injection.
Featuring three downdraught carburettors fitted on the cylinder head,
the two-litre six-cylinder developed 80 hp in regular trim, accelerating the
lightweight BMW 328 to a top speed of more than 155 km/h or 96 mph
and soon becoming the very epitome of the sports engine.
But this was far from the end of the road for the six-cylinder, with engine output
being increased to 100 and even 110 hp on competition engines. The limit
in the process was set not so much by the engine as such, but rather by the
availability of fuel restricted to just 80 octane. This, in turn, limited the
compression ratio to a maximum of 9.5 : 1, in order to avoid the risk of the
pistons burning through. So it was only the introduction of special racing
fuel that enabled BMW’s engineers to overcome this limitation, increasing
output of the BMW 328 all the way to 136 hp. And in 1941 BMW’s
engineers even conducted tests with fuel injection on this outstanding engine,
using three throttle butterflies instead of the conventional carburettors.
The BMW 501: the “Baroque Angel” full of highlights in technology.
Losing the Eisenach Car Production Plant in the War, BMW found it difficult
to make a new start in the post-war years. Hence, the first new model did not
appear until the 1951 Frankfurt Motor Show – the BMW 501.
Although relatively “classic” in its design and styling, the “Baroque Angel”
was full of highlights in technology: The two half-shafts at the front were each
mounted on two triangular track control arms running in needle bearings.
This low-friction bearing technology ensured a particularly sensitive response
on the part of the progressive springs and suspension made up on each side
of a longitudinally arranged, extra-long torsion bar.
The arrangement of the dampers was likewise quite unusual: Fitted at the
outside on the lower triangular arms, the dampers extended upwards
in an inclined position, coming to rest inside on the upper track control arm.
This avoided any contact with the sprung body and prevented even the
slightest transmission of noise.
Focusing on the steering, the engineers in Munich introduced a very special
idea on the BMW 501, applying the principle of rack-and-pinion steering
to a crown wheel segment in the interest of maximum steering precision.
The oil reservoir for the steering served at the same time to lubricate all other
front axle components, which therefore remained independent of the
regular central lubrication. The rear axle, as all testers agreed at the time, was
the “ultimate level of perfection in the development of the live axle”,
torsion bars acting on the axle right at the outside via spring arms serving here,
too, to provide the necessary suspension effect and at the same time
giving the car its longitudinal guidance.
Even the gearbox with gears being shifted straight from the steering wheel
was arranged in a different position: Instead of being bolted directly to the
engine, the gearbox with its four all-synchromesh gears was housed beneath
the front seats and connected to the engine by a short propeller shaft.
The advantage of this particular arrangement was that the footwells remained
largely free, without being impaired or cluttered by a voluminous transmission
housing. A further benefit was that the engine mounts did not have to be
re-designed for maximum torque from the transmission, meaning that the
engine was able to rest on unusually soft and smooth mounts. The bottom
line, therefore, was that the 65-hp six-cylinder, a modified version of the
engine already featured in the BMW 326, was exceptionally smooth and
refined in the BMW 501.
1954: introduction of the world’s first light-alloy eight-cylinder.
The BMW 501 nevertheless only paved the way for BMW’s most spectacular
innovation in the ’50s: The first series-production light-alloy engine in the
world and the first German eight-cylinder after the end of the War launched in
1954. Weighing in at 210 kg/463 lb, the 2.6-litre power unit in the BMW 502
was just 28 kg or 62 lb heavier than the six-cylinder in the 501.
The pistons with four rings ran in “wet” cylinder liners, that is centrifugal-cast
liners surrounded by coolant pipes.
This solution was the obvious choice right from the start because BMW
planned from the beginning to build not just the 2.6-litre with its almost square
combustion chambers, but also a 3.2-litre with exactly the same stroke but
longer bore.
The oil pump on the smaller engine was driven by a divider shaft, the oil
pump on the larger engine by a roller chain. Otherwise the higher delivery
output of the pump might have overburdened the sensitive gearwheels.
The intelligent method used to fasten the rocker arm shafts in position once
again bore testimony to the inventiveness of BMW’s engineers, with the
inner support bolts on the bearing blocks, like the pushrods, being made of
special dura-steel and extending through the entire cylinder head all the
way to the housing at the back. As a result, the support bolts maintained the
same consistent distance to the crankcase also in the transition from cold
to high temperatures, even though the different metals warmed up at a varying
rate. The result was excellent valve play compensation between cold
and warm running conditions. BMW’s advertising experts understandably
highlighted this construction at the time as “automatic valve play
compensation”.
The valves themselves were positioned parallel to one another at a 12?? angle
to the axis of the cylinders. And so while this was not a crossflow cylinder head
of modern design where the valves hanging in V-arrangement are positioned
opposite one another, this configuration helped to save space, which was
rather limited within the engine compartment of the BMW 502.
To keep the warm-up period as short as possible, the eight-cylinder
featured an oil-guiding corrugated pipe within its water shell serving as a heat
exchanger: After the engine was started cold this configuration was able to
warm up the coolant more quickly to its regular operating temperature, while
when driving fast it helped to cool the oil.
Displacing 2.6 litres, the V8 with double downdraught carburettors developed
maximum output of 100 hp when it made its debut into the market.
continued
