Your comment about spark plug demise is ironic in light of NASA research:
[clip NASA e-mail article]
DRIVING CLEAN
Researchers at MIT have demonstrated how ordinary spark-ignition car engines can, under certain driving conditions, move into a spark-free operating mode that is more fuel-efficient and cleaner. The new capability could be available in production models within a few years, improving fuel economy by several miles per gallon. Over time, it could cut oil demand in the U.S. by a million barrels a day.
Switching a spark-ignition (SI) engine to homogeneous charge compression ignition (HCCI) mode pushes up its fuel efficiency. In an HCCI engine, fuel and air are mixed together and injected into the cylinder. The piston compresses the mixture until spontaneous combustion occurs. The engine combines fuel-and-air premixing with spontaneous ignition. The result is that combustion occurs simultaneously at many locations throughout the combustion chamber.
Using the results of their engine tests as a guide, the researchers developed an inexpensive technique that should enable a single engine to run in SI mode but switch to HCCI mode whenever possible. A simple temperature sensor determines whether the upcoming cycle should be in SI or HCCI mode.
The researchers estimate that the increase in fuel efficiency would be a few miles per gallon, which may not seem like an impressive improvement, but, according to the team, if all cars in the US improved that much, it could be worth a million barrels of oil per day, which is impressive.
Read the full story at:
http://link.abpi.net/l.php?20070731A2
[end NASA article clipped from e-mail]
But - it would still be the basic engine, with improved computer controls. Same manufacturing technology, etc. (Maybe some improvements, like ceramic coatings on the top of the pistons and the heads, to allow higher temperatures (without overheating the pistons/block/heads.)- Higher temperatures would probabl make the cycle more efficient!
Mike
Already been posted on FR.........by me.......
On Homogeneous Continuous Compression Ignition, of HCCI for short.
Toyota (and Ford) call it Controlled Auto Ignition, or CAI.
GM is working feverishly on it and will have proto's to drive next year, go here for the story:
http://www.sae.org/automag/techbriefs/02-2007/1-115-2-22.pdf
It has been the subject and hot topic of many SAE papers and symposiums the last few years.
Think of it as the weight of a piston engine with almost the fuel economy of a diesel that works good on low octane fuel.
It works in a narrow band, fuel economy can increase as much as 40% and emissions drop 80%.
In my opinion it is the "Holy Grail" for engines and will make diesels boat anchors. The question has been asked on the Green Car Blogs, will GM try to incorporate HCCI into the "Prime Mover" engine on the "Volt". Since it will run at steady state, you could potentially set it up to stay in the HCCI mode all the time. If they do, Katie Bar the Door....