1989-02-01

Initial Test Results of an Electro-Hydraulic variable-Valve Actuation System on a Firing Engine 890678

An electro-hydraulic variable valve actuation (henceforth, referred to as WA) system has been developed for spark ignition engine applications. This is a report of its successful initial testing.
Motoring tests were first conducted to determine any cylinder to cylinder variations in charging efficiencies. These were then corrected by individual intake valve timings.
Then testing was conducted on a firing engine at both part and full load over a full range of engine speeds. The brake specific fuel consumption (bsfc) was considerably improved at low speeds by the WA system. However, the bsfc results of the WA system were worse than those of the throttled engine system at higher speeds and low loads. The cause of this problem was determined to be poor mixture preparation and various corrective measures are now being studied.
The WA system was very effective at full load over the entire speed range and increased output torque by more than 10% at the lower engine speeds compared to the production engine.

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