OT: Is it possible to convert Diesel Engine to LPG

I think not due to the high compression ratio that will force propane to self ignite.

Well, anything's possible, but this is probably impractical. Some large diesels are able to run on a combination of gaseous fuels and diesel, where a subcritical charge of gaseous fuel is introduced into the intake and is then ignited by a small diesel injection, but I doubt it could be done efficiently on an automotive scale.

Spark ignition engines, by comparison, are far easier to convert to gaseous fuels.