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AutoBlog: We take a quick spin in GM's latest HCCI engine prototype

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Filed under: Hybrids/Alternative, Green, Tech, GM, Saturn

hcci-aura-580.jpg

Since our first encounter with General Motors' HCCI (homogeneous charge compression ignition) engines in August 2007, the powertrain research engineers at GM's Tech Center in Warren, MI have continued plugging away at the technology, trying to turn it into a marketable reality. The basic premise of compression ignition is simple. Based on the Ideal gas law (PV=nRT), if you decrease the volume of a particular quantity of air, the temperature rises to the point where fuel will spontaneously combust.

The hard part is controlling the pressure, temperature and air/fuel mixtures precisely enough to manage that combustion without causing excess noise and engine damage. When we first tried the HCCI prototypes a couple of years ago, the engines had a fairly narrow band of HCCI operation with the engine running in basic spark ignition mode the rest of the time. Thanks to a newly developed mixed-mode HCCI feature and external EGR, the engines can now run in HCCI from idle all the way to 60 mph.

We had a chance to drive a Saturn Aura with an HCCI engine based on the 2.2-liter EcoTec four-cylinder around the streets near the Tech Center. The engine ran smoothly and transitions between HCCI and spark ignition really couldn't be felt. The only indication of a transition was a slight ringing sound over the first couple of power cycles after transition.

The basic hardware for a production HCCI engine is in place now, with the only new piece of hardware being a combustion chamber pressure sensor. GM is continuing to work on the control software to make this a robust system and even adapting the homogeneous charge and pressure sensors to diesel engines to reduce NOx emissions. GM says that HCCI engines can achieve about a 15% improvement in fuel efficiency compared to a similar spark ignition engine - at a much lower cost than a hybrid. The automaker hopes to have HCCI engines in production in about five years.

[source: Green Fuels Forecast]

Continue reading We take a quick spin in GM's latest HCCI engine prototype

We take a quick spin in GM's latest HCCI engine prototype originally appeared on Autoblog on Tue, 26 May 2009 14:00:00 EST. Please see our terms for use of feeds.

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Interesting... I wonder if this is anything like the 'stratified' charge engines I recall reading about 20+ years ago?

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I am an eternal optimist, but I actually believe this is one for OZ. I actually believe other technologies will happen in place of this one.

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I've been reading recently that the regular old gasoline ICE will make significant improvements in the next few years. Take that, hybrids!

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great. will this be used with DI too...or a sort of port injection?

a 2.0L with this for a "cruze", prolly be great

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I've been reading recently that the regular old gasoline ICE will make significant improvements in the next few years. Take that, hybrids!

Uhmmm dont hybrids use regular old gasoline ICE's to power the hybrid? :P

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Interesting... I wonder if this is anything like the 'stratified' charge engines I recall reading about 20+ years ago?

Could be, although I think the Honda CVCC engines with their pre-combustion chambered heads were also referred to that way in the 70's.

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great. will this be used with DI too...or a sort of port injection?

a 2.0L with this for a "cruze", prolly be great

I think DI is required for it to be able to work.

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I've been reading recently that the regular old gasoline ICE will make significant improvements in the next few years. Take that, hybrids!

GM's PR (at least that's what this looks like to me) is promoting HCCI in conjunciton with Hybrids:

http://videos.howstuffworks.com/multivu/32...ngine-video.htm

Perhaps we will be able to have HCCI VS VCR fight in the future:

http://www.greencarcongress.com/2009/04/ho...r-20090422.html

Interesting times.

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