search: E&MU: Spark vs. Compression: Natural Gas ABCs
Top brass from Cummins and Westport discuss differences between HPDI and SI. Good technical article.
Message boards acting up the last couple of days! This is the second time I posted this message.
A quote from the article:
"The HPDI engine uses LNG because high pressure is required for injection, and it’s not practical to compress gaseous fuel to a high pressure on the truck. Thus, a cryogenic refrigeration-type fueling station is necessary."