GM and "Lean-Burn"

[gone-ot]

...Lean-Burn project GM has been working since 2010:

http://www1.eere.energy.gov/vehicles...ith_2011_o.pdf

http://www1.eere.energy.gov/vehicles...er10_viola.pdf

[Daox]

Some interesting info. Looks like to meet current emissions standards they're gonna need a lot of extra junk. Only other thing I saw that surprised me was they were only targetting a 13% or greater increase in highway FE. Seems to be setting the bar a bit low IMO.

[rkcarguy]

That's around the limit of gains you can see unfortunately, Honda's lean burn runs around 20:1 AFR best case which is going to offer ~20% better FE.
There is alot more gains to be made in the aero dept, which I'm sure is being overlooked as usual.
If you want to make big gains on gasoline(IMO), it needs to be lean burn+ water injection+ light weight+ aerodynamic.
The water injection also has the bonus of pulling a good portion of the NOx out of the emissions and takes care of that concern as well.

[brucepick]

In my Civic HX it looks like approx 20% reduction in mpg at the instant it goes into lean burn. However there's a power reduction so it needs a bit more foot pressure on the accelerator. I estimate I end up with about a 10% net gain after stepping into it a bit.

There are NO level roads in this state so there's always a grade and a change in grade to throw things off a bit.

[tjts1]

Whatever happend to GM's HCCI project?

[Phantom]

I did not get to read the links yet but it should be fine in passing emissions at about 17.8:1 the HC and NOX is about the same as at 14.7:1 but the CO drops a bit.

[gone-ot]

...here is an old (2008) article about the GM HCCI project:

• HCCI Technology - GM and its Homogeneous Charge Compression Ignition fuel-saving engine tech - Auto News - Motor Trend

...something from SAE World in 2010:

• SAE World Congress Report: GM's HCCI technology display is a snore - Detroit Automotive technology | Examiner.com

...and, something more recent (2011):

• Green Car Congress: GM exploring different valving strategies to extend HCCI operation for high loads; benefits of a Positive Valve Overlap approach

...and, an old (2001) 'promises' paper to Congress:

• http://www-erd.llnl.gov/FuelsoftheFu...es/hccirtc.pdf