DTS-Si stands for digital twin spark - swirl ignition, it is similar to DTS-i technology difference being the cylinder has grooves which causes turbulence of the air fuel mixture entering the cylinder making it 'swirl' hence better combustion takes place, giving better efficiency and power. A review has been made of rotating flow (swirl and tumble) in premixed spark-ignition engines and its effects on turbulence generation and flame propagation. Rotating flow can significantly increase turbulence intensity during the combustion period.
This in turn can lead to a reduced burning period and increased thermal efficiency. Rotating flow, possibly in combination with squish, can be particularly important for combustion of lean mixtures or with alternative fuels of low laminar flame speed. In general, rotating flow can substantially increase flame propagation speed, reduce cyclic variations, and expand the lean limit, though excessive rotational motion can have deleterious effects on induction system flow resistance and also on heat transfer and thermal efficiency.
Much research work has been devoted to swirl (rotational motion around an axis parallel to the axis of the cylinder), but in recent years increasing attention has been paid to tumble (rotational motion around an axis perpendicular to the cylinder axis). Swirl and tumble have distinctive characteristics and can interact differently with piston motion and squish. The optimum rotating flow field may be a combination of the two kinds of rotational motion. The principal features of the mean velocity and turbulence fields associated with these rotational motions are reviewed, as well as the mechanisms for decay, generation, transport and enhancement of in-cylinder turbulence.