The Volvo 850 engine concept
The engine in the Volvo 850 GLT is
an in-line 2.5 litre five-cylinder called
the B5254F. Thanks to an extremely
compact design of the engine and
transmission (See Technical in-
formation Transmission) it has been
possible to install it transversely (fig-
ure 1), still allowing for excellent han-
dling properties and an extremely
small turning circle (10.2 metres) for a
front wheel drive car of this size. The
Volvo 850 GLT is the first passenger
car that has an in-line five-cylinder en-
gine installed transversely driving the
front wheels. Overall length of the
complete powertrain, engine and trans-
mission, is only 948 mm.
The main characteristics of the
B5254F are:
- Five cylinders with four valves per
cylinder and a high compression ratio
- High performance and good fuel
economy without negative influence
on driveability
- Minimized engine vibrations thanks
to inherent engine and transmission ri-
gidity, damped engine and suspension
system and a separate insulated sub-
frame carrying the powertrain.
- A variable induction system, the V-
VIS (Volvo Variable Induction Sys-
tem) and an extractor type exhaust
manifold. Since this is located be-
tween the engine and the firewall, the
position of the catalyst could be close
to the engine which provides faster
warming-up of the catalyst and thus
l ow exhaust emissions.
Among the basic development goals
for the engine concept were a high de-
gree of reliability and long service
life; high energy efficiency; easy
maintenance; rational manufacture;
compactness in size; low weight and
low noise level.
As for reliability and service life, the
engine has a life span of more than 20
years or a total driving distance of
more than 200.000 without needing
disassembly and with all vital parts in
good working condition.
Regarding high energy efficiency, the
gas flow has been optimized with the
aid of computer simulations and laser
measurement technology in order to
ensure efficient use of energy.
During the development of the en-
gine, Volvo Car Corporation service
personnel have contributed with their
know-how in order to achieve high re-
liability with a minimum of main-
tenance. A number of automatic func-
tions minimize the need for manual
adjustments:
- Hydraulic tappets (no adjustment of
valve clearance)
- Automatic belt tensioners for cam-
shaft and auxiliary drives
- Adaptive functions of the control
systems compensating for system tol-
erances and wear, temperature and
fuel variations ensuring optimum fuel
metering and ignition timing
- Automatic idling speed adjustment
and air/fuel ratio
