REVIEW: 2015 Chevrolet Silverado 2500HD bi-fuel a case study in CNG vs. gas ... - Equipment World Magazine
A whoosh, like connecting an air hose to a compressor, is the only thing that lets me know I’m in business filling the bed-mounted fuel tank in the 2015 Chevy Silverado bi-fuel CNG 4×4 I’m driving. I tap the CNG switch at the far end of the row of auxiliary switches along the bottom of the Silverado’s center console and up pops the CNG fuel gauge’s bar graph on the digital dash display. The toggle switch’s indicator light blinks for a few seconds then remains on, indicating the truck’s bi-fuel system has switched over to CNG and, in doing so, switches to a separate engine control module (ECM). Good to go. . CNG vs. gasoline Using two separate ECMs was the only way the GM engineers could optimize the driving characteristics of the two very different fuels. The CNG module has different engine and transmission calibrations than the module on the gasoline side: Injector durations and flow, engine timing, transmission shift points and a host of other calibrations have been changed to meet stringent EPA... 0L V8 makes a respectable 360 horsepower on gasoline but drops 59 of those horses when CNG runs through it. GM CNG engineer Mike Jones says the drop in power is a result of tuning the engine so it meets EPA requirements. Source: www.equipmentworld.com
