“…Common themes for these alternatives are reduced combustion temperatures (1600-1800 K peak) and control of local fuel=oxidant=diluent compositions so that NOx and soot production can be simultaneously mitigated. Future engines may employ such low temperature combustion (LTC) schemes where boosted operation (up to 5-6 bar) and=or very high compression ratio (CR $ 50) could be employed to address power density and energy loss issues (e.g., Aoyagi et al, 2006;Buchwald et al, 2006;Cairns & Blaxill, 2005;Chen & Mitsuru, 2003;Edwards et al, 2007;Gharahbaghi et al, 2006;Hyvö nen et al, 2003;Kalghatgi et al, 2006;Kim et al, 2007;Olsson et al, 2004;Sako et al, 2005;Teh & Edwards, 2006;Teh et al, 2008aTeh et al, , 2008b. Under these conditions, ignition pressures could reach 100-300 bar with peak pressures to 500 bar (McIlroy & McRae, 2007); this is substantially higher than for current production engines where maximum pressures are generally limited to 200 bar.…”