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Multi-dimensional computations were made of spark-ignited premixed-charge combustion in two engines having pent-roof-shaped combustion chambers and two intake valves per cylinder, one with a central spark plug and the other with dual lateral spark plugs. The basic specifications for the two engines were the same except for differences in the number of spark plugs and exhaust valves. The effects of swirl and equivalence ratio on combustion, wall heat transfer, and nitric oxide emission characteristics were examined using a global combustion model that accounts for laminar-kinetics and turbulent-mixing effects. The initial conditions on both mean-flow and turbulence parameters at intake valve closing (IVC) were estimated in order to simulate engine operation either with both intake valves active or with one valve deactivated. The predictions were compared with experimentally derived pressure-time, heat loss, and nitric oxide emission data.