V70 GL L5-2.4L VIN 55 B5254S (1998)
even, high torque over a wide speed range.
A: At Rpm below 1,800 rpm; both intakes are open regardless of throttle opening. This allows a rapid increase in airflow when the throttle is
opened, which gives a rapid response at low Rpm - when starting and accelerating at low speed.
B: At Rpm between 1,800 and 4,200 rpm; and if the throttle is more than 80° open, the dampers on the shorter intakes are closed, and only the
longer intakes are used. These are tuned for this speed range so that the air in the plenum chambers and intakes is made to resonate with the
movement of the pistons and valves. This means that air in the intakes pulses in time with the opening of the valves and is pumped into the
cylinder when the intake valve opens. This charges the cylinders better than a conventionally aspirated unit.
A new parameter has been introduced for model year 1994 and later which takes "load" into account. This means that the dampers on the shorter
intakes can be closed before 80°.
C: At Rpm above 4,200 rpm; both intakes are open regardless of throttle position. Air can flow through both intakes to the cylinders doubling
airflow. At high Rpm the combination of the long and short, larger diameter intakes provides the right resonance for maximum torque. The B5254
delivers 215 Nm (168.3 ft lb) at 5,000 rpm.
The long intakes are designed for high volumetric efficiency at Rpm between 1,800-4,200. Using the long intakes alone at high Rpm would restrict
air supply because the air pulses would no longer correspond to the opening of the valves.
The damper spindles (a long spindle for three cylinders and a short spindle for two cylinders) are supported in bearings in the intakes. The linkage
mechanism is designed so that dampers seal completely as leakage between damper and seat will impair engine torque at those speeds where the
dampers are closed.
NOTE: In the event of vacuum system faults, the dampers remain open, resulting in reduced torque at intermediate speeds.
