A process (100) is provided for enhancing homogeneous combustion and improving ignition in rotary and reciprocating piston IC engines. Physical embodiments supporting this process have secondary chambers (32) embedded in the cylinder periphery (36) to initiate radical ignition ('RI') species generation in an earlier cycle for use in a later cycle. These communicate with the main chamber (34) via small conduits (42). Coordinated with the progressions facilitated by these secondary chambers (32) are novel control measures for regulating the quantities of RI species ultimately generated. The pre-determinable presence of RI species so supplied then alters or adds controlled variety to the dominant chain-initiation reactions of the main combustion ignition mechanism of the later cycle. This presence does so by lowering both the heat and the fuel ratios required for starting and sustaining combustion. This presence thus improves combustion and reduces emissions in radical ignition, spark ignition and compression ignition engines.