Not sure why GM put out a press release on its Homogeneous Charge Compression Ignition (HCCI) engine program today. There was nothing new to announce and the technology is nowhere near production ready. Can't imagine it has anything to do with looking good for it's new owners.
For those that aren't familar, gasoline-fueled HCCI engines use high pressure to induce ignition much like a diesel. They promise improved mileage along with cleaner emissions. Numerous manufacturers have been working on such engines, but they work much better in a lab than they do out in the real world. In other words, don't expect to see an HCCI on any options list anytime soon.
1487 says:
11:18 AM, 05/20/09
The real question is what is the point of this post on Straightline.
They actually have tested their cars in the real world. The issue isnt that they dont work, its that they have some NVH issues at higher speeds and there are durability questions that have to be answered. And of course there is cost. I would say HCCI will definitely be available before the 39mpg mandate goes into affect.
firstwagon says:
11:31 AM, 05/20/09
There are more problems then that and there are real questions as to whether the advantages will exceed the disadvantages.
I think we will see it eventually but I don't expect it in time for 2016.
While it works great with diesel, gasoline has very different properties and it's hard to overcome that.
Here's a quick list of some of the problems ....
"High in-cylinder peak pressures may cause damage to the engine.
High heat release and pressure rise rates contribute to engine wear.
The autoignition event is difficult of control, unlike the ignition event in spark ignition (SI) and Diesel engines which are controlled by spark plugs and in-cylinder fuel injectors, respectively.
HCCI engines have a small power range, constrained at low loads by lean flammability limits and high loads by in-cylinder pressure restictions.
Carbon monoxide (CO) and hydrocarbon (HC) pre-catalyst emissions are higher than a typical spark ignition engine, caused by incomplete oxidation (due to the rapid combustion event and low in-cylinder temperatures) and trapped crevice gases, respectively."
1487 says:
12:29 PM, 05/20/09
Like I said, I bet you will see it before 2016. The issues are primarily related to driveability and durability. The fact that there are working prototypoes out there capable of 55mph means a lot of work has already been done. The new standards guarantee that efforts to refine this technology will step up. The point is to make gasoline almost as efficient as diesel.