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The next big step in gasoline engines burns fuel like diesel engines burn diesel. But hurdles remain. (http://money.cnn.com/2008/05/30/autos/hcci/index.htm?postversion=2008061109)

http://www.cleanmpg.com/photos/data/501/honda_hcci_4stroke.jpgPeter Valdes-Depena - CNN/Money - June 11, 2008

Honda’s own HCCI ICE on the test bench as seen in late 2005.

A diesel like gasoline engine that still has trouble at very low and high output. If Honda has solved it, could this be there own next killer app? -- Ed.

NEW YORK -- Car companies are working to perfect a new generation of gasoline engines that could get up to 20% better fuel efficiency. The system, which burns gasoline without spark plugs, relies in massive amounts of speed and power - the computer kind - to work.

It's called Homogenous Charge Compression Ignition, or HCCI. General Motors has been allowing journalists to drive a test vehicle with this technology. It clearly isn't quite ready for the mass market, but GM insists that it's finally in the home stretch after years of trying.

"You're basically getting the best of gas and diesel all together," said Kelly Mundt, director of gasoline system marketing for auto parts supplier Bosch, which is working on some components needed for this new engine system… http://money.cnn.com/2008/05/30/autos/hcci/index.htm?postversion=2008061109

W -

Thanks for posting these. In the medium term, (say 2009 - 2012), consumers should start seeing manifold choice when it comes to cars with 40+ MPG.

By 2012 - 40+ MPG will be the baseline

If it just ran "at a constant rate" with much higher FE, then it sounds like it might be perfect
for charging batteries.

It's amazing what's starting to come out of the woodwork these days.
I've got a feeling we are about to witness some real technological history being made during the next decade.

Somewhat unfortunately, the HCCI mode of combustion is best suited for low-load situations like steady-state cruising, and probably wouldn't be great for a series hybrid (which I presume Xringer was alluding to). As was mentioned in the article, HCCI will probably mesh best with a parallel hybrid, which could do a better job of keeping the engine in a low-load state.

Of course, since I drive a diesel car, I tend to be more interested in seeing how HCCI technology can be applied to diesel engines. Unfortunately, that's not very clear... It seems to me that modern diesels have all of the elements necessary to do HCCI -- very fast piezo injectors can give precise control over the mixing of fuel and air, and many newer injectors are also including a pressure sensor to monitor combustion right inside the cylinder. HCCI engines that run on gasoline also have to be beefed up because the combustion occurs all at once, resulting in much greater in-cylinder pressures. Of course, maybe diesels running HCCI would have to be beefed up too, though I know that researchers doing HCCI research with gasoline often start with diesel engine blocks just because they're already designed to handle greater pressures.

Anyway, from what I can tell, HCCI is basically a type of lean-burn. However, it has much better emissions characteristics since the fuel is getting consumed virtually all at once.

Uh, maybe I'm missing something but aren't diesels the model HCCI is shooting for? All the extra fancy stuff is because gas doesn't like to ignite from pressure the way diesel does...

Uh, maybe I'm missing something but aren't diesels the model HCCI is shooting for? All the extra fancy stuff is because gas doesn't like to ignite from pressure the way diesel does...
It's close to how a diesel works, I don't think the article did a good job of explaining that part. The H in HCCI is for homogeneous. The combustion chamber contains a homogeneous mixture of fuel and air, and when the mixture gets hot enough through compression, it combusts. An advantage of the homogeneous mixture is that an HCCI engine has lower emissions than a diesel engine. A diesel does not have a homogeneous mixture when combustion takes place.

Thanks for the clarification, Mike. :)

Hi All,

Here is a further clarification. In a HCCI engine the fuel and oxidizer mixture is mixed well before combustion. And combustion occurs at all places in the cylinder simultaneously, but not explosively.

In a Diesel, the fuel burns as its squirted into the cyliner. This is why the high pressure computer controlled injectors on modern diesels improve things so much (and acetone is useless on these cars). The high pressure allows a smaller orifice, which creates smaller fuel droplets. And the quickness of the piezo injectors allows the programing of a custom fuel volume versus time profile for the specific load and RPM.

This can make for some really fantastic SHM (super highway mode) cars. Some of the National Labs research is looking at HCCI compression ratios of as much as 80:1. Which gets the heat engine up in the 50 % efficiency range. The purpose of this research is for the military hybrid scout/recognisance car however.

I really like the HCCI engine concept. I suppose that mating it to a hybrid propulsion system would smooth out some of that technology's rough edges. I'd love to see a plain-vanilla Civic boosted up to 42 MPG or so via HCCI.

"The Next Big Step" is gasoline or the last? I'm hoping we are getting close to sending gasoline the way of the dinosaur....apropriate considering...