You would inject the fuel directly into the cylinder, like a diesel or a gasoline direct injection engine. The problem is gasoline is made to resist ignition at high pressure and temperature. First you would have to get the cylinder pressure high enough at the point of injection (I don't know how high of the top of my head). The way to do this is increase the compression ratio, likely higher than that in a diesel engine, although turbo charging would help. Then the best case would be at full load. As load dropped, so does cylinder pressure, and hence compression ignition would be less likely.
Second, you have to inject the fuel into this high pressure environment. To inject into a high pressure environment, you would need even higher pressure in the fuel system. This is not an easy task. Right now DI Gasoline engines are pushing around 120 bar, but with much difficulty.
If you took care of those problems, which are not impossible, then it should work.
Bottom line... It is not impossible, just impractical.
To the best of my knowledge... No, none in production. The closest to this that I know of is a CI engine that uses directly injected diesel fuel as the pilot ignition source, but the bulk of energy (at full load) comes from natural gas. The natural gas is premixed with air in the intake manifold. I don't know if this engine ever went into production, but I think Detroit Diesel published some papers on it in about 1996.
On a slightly different approach the orbiatl engine is still spark ignition, but has direct injection of gasoline, and is a superchrged two stroke design.
I was fortunate enough to drive a prototype 1.4 litre 3 cylinder installed in a small car - very impressive torque, and emissions. The fuel economy was pretty good, but of course the supercharegr hurts that. The torque was amazing - 4th gear at 500 rpm, and it pulled like a train.
What would be the advantage of going to CI rather than SI?
Cheers
While reading Turbochargers by Hugh McInnes, I read his diesel section. According to him, fuel efficiency stays about the same when turbo'ing a diesel engine, yet emissions drop and power rises. That seems like a good thing in my book. So, is that because it's a CI engine or is it because it's diesel.....
