Tech Briefs
February 2007
GM moves closer to market with HCCI
Designing an HCCI (homogeneous charge compression ignition) gasoline engine to work over a wide rpm and load range has been an enormous engineering challenge, but General Motors believes it finally knows how, and will introduce a demonstration vehicle next year. To satisfy HCCI’s requirements for precise control of mixture, temperature, and pressure throughout the cylinder, GM will use direct fuel injection, cylinder pressure sensing, variable (two-step) valve lift, and variable intake and exhaust valve timing with dual electric/electronic cam phasers. This fast-acting, precise, but expensive technology is currently used only on 2007 Lexus LS460 intake camshafts.
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