GM Road Tests HCCI Engine

Edward Niedermeyer
by Edward Niedermeyer
gm road tests hcci engine

Green Car Congress reports that GM is road testing a Saturn Aura equipped with a homogeneous charge compression ignition (HCCI) engine. HCCI technology compresses a lean air-fuel mixture in the cylinder, which ignites without spark plugs, creating low-temperature, flameless combustion. GM says HCCI combustion reduces NOX and particulate emissions and offers 15 percent better fuel efficiency. The 2.2-liter modified ECOTEC engine is set up to use traditional spark ignition when starting, driving over 55mph and other low-temperature or high-load circumstances. It switches to HCCI mode for most driving. The modified mill makes 180hp and 170 lb/ft of torque, with additional help from direct injection, variable valve lift, dual electric camshaft phasers and individual cylinder pressure transducers to "control the combustion as well as deliver a smooth transition between combustion modes." Props to GM for developing technology which doesn't require them to reinvent the [s]wheel[/s] battery, but it'll be a while before HCCI is ready for prime time. That said, direct injection– as seen on the new Porsche Cayenne and other, more prosaic VeeDubs– had a rocky start.

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  • Wolven Wolven on May 06, 2008

    Flameless combustion? Are you sure about that? Or is it just "sparkless" combustion?

  • Joeaverage Joeaverage on May 07, 2008

    So that 15% increase in efficiency will guarantee 15% larger vehicles? How about 15% BETTER vehicles? FWIW I think the technology is pretty cool. Any little thing helps.

  • Gawdodirt Gawdodirt on May 07, 2008

    Good point. No such thing as "flameless combustion." Credible? Same as "dry water?" Good for them. So why the bashing anyhow? Seems like regardless of the financial woes, they're still trying to produce. Guess they don't read the blogs!

  • Jonathon Jonathon on May 07, 2008

    I think what that means is that there is not a flame front moving through the cylinder—it all burns at the same time. You could always, you know, look it up. ;)