New engine from GM (HCCI)

[granatl]

A gas engine w/o spark plugs (diesiling on gas)
DailyTech - GM Hopes to Have First Diesel-Like Compression Gas Engine on the Market

 

[Darkcyde]

A gas engine w/o spark plugs (diesiling on gas)
DailyTech - GM Hopes to Have First Diesel-Like Compression Gas Engine on the Market

great news! I hope it comes on their next generation turbo buick! Yea theres a new one, and no we in the U.S. don't get it. Everyone here hates it but I dont care I like it, just like I like this type of technology. But then again most people can't get past looks here so I understand why people hate it. I love what in it. Buicks first turbo car in over 2 decades, so I don't really care what it looks like.

thanks for posting this information

 

[fritznh]

A gas engine w/o spark plugs (diesiling on gas)

I believe that the engine has spark plugs and direct injection. Additionally, it has variable valve timing which is what allows you to actually run in HCCI mode. What happens is that it traps a lot of exhaust gas in the chamber from the previous cycle by not opening the exhaust valve very long, then it compresses that exahust gas instead of blowing all of it out, then opens the intake a little to let in just enough fresh charge to burn. It doesn't burn, though, it gets compressed until it goes pop. HCCI is also known as controlled auto ignition or CAI. Lotus has been working on it for a long time (like 5 to 8 years, so not really all that long...).

If you put in too much fresh charge to get more power out, the engine knocks too hard and it will break eventually. So at higher outputs, you go back to regular spark ignition mode. You also need the spark plugs to idle because you don't have enough heat to make it go pop, so you need to run in normal mode again.

The technology is good, though. You get good fuel economy while not making any pollutants. Not as good fuel economy as a diesel, but a lot cleaner. If they calibrate the engine right, you should not feel any transition between HCCI mode and regular mode, but that is really tough. The engine also sounds different in the different combustion modes so you'll be able to tell.

 

[turbodave231]

SAE magazine- Automotive Engineering published an article on this.

GM has been working on this technology for several years now. Its called Homogenous Charge Compression Ignition. Last I heard, they were running an Ecotech L4 engine using this system.

Big gains in efficiency but unstable at an idle. They need to run spark plugs during unstable operation. Very cool and leading edge in IC technology.