How does the dual-plenum induction system work at low engine speeds?

At low speed the throttle valve 53 is opened only slightly, high induction vacuum on vacuum motors 67 holds throttle valves 64 closed, and all intake air flows through inlet device 48 into plenum chambers 45 and 46, then through long conduits 58 and passages 59 to induction passages 31, giving a long air path with laminar, high-velocity flow for good combustion.

What happens in the mid-range as engine load increases?

Before the secondary throttle valves 64 open, induction charge flows through the communicating area 42 into the combustion chambers 25 via both induction passages 31 and 32 and intake valves 33 and 34. This communication significantly improves mid-range performance and reduces the dip in the torque curve.

How is maximum power achieved with this induction system?

As load continues to increase, induction vacuum drops until the vacuum motors 67 no longer hold the control valves 64 closed and they open, substantially increasing the effective induction area per cylinder. The short passages 69 offer low flow resistance and can be tuned for the desired high-load flow.

How is fuel delivery controlled in this system?

A single vane-type flow sensor (72) senses air flow into the induction system and is connected through a control system that regulates the fuel delivered to injection nozzles 44 through a pair of fuel manifolds 73 located near cylinder heads 23 and 24.

What prior application does this construction reference?

The text states the construction described is substantially the same as that described in co-pending application Ser. No. 634,795.

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Ford Taurus SHO Dual-Plenum Intake Patent Text - SHO & Tell Summer 2001 Page 14

Intake induction system patent text page describing valve body passages and plenum chambers Summer 2001

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Text-only magazine page continuing the dual-plenum induction-system patent: valve body induction passages, single-flow-sensor airflow control, and short intake runners for power.

AI caption August 2007 · Photo 936 of 1028

This document is page 14 of the Summer 2001 issue of the "SHO & tell" newsletter. It reproduces a portion of a patent-style technical description of a dual-plenum engine induction (intake) system. The text explains how two plenum chambers (45 and 46) each feed the intake passages of the opposite cylinder head (23 and 24) via long conduits, providing long air paths for laminar, high-velocity flow at low speeds and rapid flame propagation for good combustion. It describes a common manually operated throttle valve (53), secondary throttle/control valves (64) held closed by vacuum motors (67), a linkage system (66), an air flow sensor (72, vane type), and fuel manifolds (73) supplying injection nozzles (44). The operation is described across three load ranges: at low speed, air flows only through the long primary passages; at mid-range, charge flows through a communicating area (42) to both sets of induction passages, reducing the torque-curve dip; and at high load, the vacuum-operated valves open the short secondary passages (69) to increase effective induction area for maximum output. The text notes the construction is substantially the same as described in co-pending application Ser. No. 634,795. A reader learns how a variable/dual-stage intake manifold improves low-end, mid-range, and peak performance.

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Frequently asked questions

How does the dual-plenum induction system work at low engine speeds?: At low speed the throttle valve 53 is opened only slightly, high induction vacuum on vacuum motors 67 holds throttle valves 64 closed, and all intake air flows through inlet device 48 into plenum chambers 45 and 46, then through long conduits 58 and passages 59 to induction passages 31, giving a long air path with laminar, high-velocity flow for good combustion.
What happens in the mid-range as engine load increases?: Before the secondary throttle valves 64 open, induction charge flows through the communicating area 42 into the combustion chambers 25 via both induction passages 31 and 32 and intake valves 33 and 34. This communication significantly improves mid-range performance and reduces the dip in the torque curve.
How is maximum power achieved with this induction system?: As load continues to increase, induction vacuum drops until the vacuum motors 67 no longer hold the control valves 64 closed and they open, substantially increasing the effective induction area per cylinder. The short passages 69 offer low flow resistance and can be tuned for the desired high-load flow.
How is fuel delivery controlled in this system?: A single vane-type flow sensor (72) senses air flow into the induction system and is connected through a control system that regulates the fuel delivered to injection nozzles 44 through a pair of fuel manifolds 73 located near cylinder heads 23 and 24.
What prior application does this construction reference?: The text states the construction described is substantially the same as that described in co-pending application Ser. No. 634,795.