Hi, if I may I would kindly suggest for consideration:
when adding something to the fuel one has to look more into what comes out as a pollutant.
on the other side engine cooling, and in particular the cooling the upper part of the cylinder-liner on the exhaust side, can significantly improve anti-knocking quality of engines, regardless of fuel.
Hi, in CI engine, ignition delay and temperature of auto-ignition depends on the chemical composition of the fuel. To improve the Knock resistance of diesel fuel, a small amount of compounds like ethyl nitrate or ether or amyl nitrate can be added to the fuel. The anti-knock additives interrupt the chain reactions that lead to knock [1].
[1] A. Groysman, Corrosion in Systems for Storage and Transportation
of Petroleum Products and Biofuels, Chapter 2, Fuel Additives