Gasoline Diesel

[Fritz The Cat]

Lots of great answers guys, Just one thing, theres lots of talk about the problem of spontanious ignition under compression. While this is true, it must be noted that there is no fuel in the cylinder during the compression stroke of a diesel engine. Therefore, no spontanious ignition, no preignition. The air is compressed to create a high temp. and the fuel is injected under high pressure into the super heated air, igniting the fuel. This creates a nice flame front to drive the piston down. As all fuel enters the cylinder through the injector, the size of the flame front is controled by the amount of fuel injected and the length of the fuel pulse.

Kind of like a very high compression engine with a high powered injector where the spark plug used to be.

[AnArKey]

The term that will get lots of hits for everyone to read up on, and this is real cool to me anyway, I enjoyed all the reading, is "HCCI ignition".

Compression ignition of a homegenous mixture, when it has been done in test conditions, shows to be much more efficient than the type of delivery a diesel uses, and which you so perfectly clarified. You don't have the disparity of rich/stoich/lean in the mixture, which leads to unburnt fuel. You have that instant light off I spoke of, which REALLY kicks the cylinder pressure up. The trick has been, and continues to be, controlling the autoignition point. They have tried shifting the effective compression or level of internal EGR (left over gasses) by means of variable valve control, controlling intake air temp carefully, and the one that interests me, modifying the effective octane of the total fuel charge by varying portion of a high vs low octane fuel. Probably not gonna get much attention because it wouldn't work in wide use, they are not about to add a heptane nozzle at the gas stations. But for me, maybe. It also seems to offer the highest level of control, and the potential to have the flexibility to govern the correct ignition point from 1-3bar of intake manifold pressure, from 5L to .85L.

Back to diesels, why are they all low rev? Is that just the limitation of the diesel oil fuel (burns slow), or the delivery rate of the fuel injectors? Disel injector are only avilable to inject during a brief moment in the entire cycle (10-20%), where gasoline port injectors can spray as much as 100% of the time.

Basically, can you have a 8k redline compression ignition motor?

Here's a example of a gasoline, compression ignition, PORT injected motor:
http://www.yet2.com/app/utility/exte...expatent/12236

However it does say lean burn, which leads me to believe they don't increase the AFR to stoich or beyond for full power.

[MustangRoadRacer]

has anyone ever heard of a rotary diesel?
is it possible?
I thought that due to the relatively low compression of the engines it wouldn't work, but a friend was talking about one he saw.
thoughts?