[Getready]

I read along time ago they were working on this

I believe they need stronger engines to withstand the pressures....but then couldnt they also imcrease the pressures in diesels also. I dont know

[onona]

Pressure and temp

[Axenolith]

You have to solve predetonation issues with gasoline, and probably the same with diesel at higher pressures. On top of that the charge probably has to enter the cylinder at an extremely high value of homogeneity, i.e. no lean or overly rich locations throughout the charge.