ORNL team achieves diesel-like efficiency with SI engine International Journal of Engine Research. The ORNL team conducted engine experiments with both 91 RON E10 gasoline and liquified petroleum gas (LPG). The unique high stroke-to-bore engine design (1.5:1) with cooled exhaust gas recirculation (EGR) and high compression ratio (13.3:1 for both fuels, with additional runs at 16.8:1 for LPG only) improved engine efficiency by up to 30% compared with a production turbocharged gasoline direct injection spark ignition engine. Comparison of the derived brake thermal efficiency of the ORNL research engine (LSE) running LPG to 2019 production Cummins ISB diesel. Splitter et al. A major benefit of SI engines is that they allow the use of low carbon content fuels like methane and propane. Additionally, criteria pollutant control, like unburned hydrocarbons, carbon monoxide, and nitrogen oxides (UHC, CO, and NO