It IS just a diesel but it isn’t, Confusing? Yeah. Gas can be compression combusted like diesel fuel can but the results can be spectacularly bad. The greater volatility of gasoline mean the ignition can start too early in the compression stroke on a running engine plus the more rapid combustion can shove the crank out of the block. That’s why we haven’t seen compression ignition gas engines before now.
With the advent of direct fuel injection at very high pressures for both diesel and gas engines, we now have the technology to squirt fuel in at any point in the cycle. Gas squirted into the combustion chamber near TDC when it is more than hot enough to light off the mixture means the spark is eliminated. Multiple squirts can create a localized area of 14.7:1 air-fuel when the overall combustion chamber is lean, means the engine will run fine and give good MPG’s. Cold engines may still require spark plugs, much like the need for diesel glow plugs.
We’ve already gotten to 11:1 compression ratio engines that run on regular gas. How about 18:1? or 22:1? Promises greater efficiency with the lower emissions of a gasoline engine.
The reason I know a bit about this is a buddy of mine was working on exactly this for another manufacturer and we’d had many conversations about this and how it’s possible.