Guys i was in extensive traveling in last month n half. Drove almost 25k. Last week while checking water in radiator i forgot to cap it back as it was fajar time n was darkness. After driving almost 10km my car stopped automatically. The problem was the water drain. Cut shot piston got warmed n now giving a little sound which is heart breaking for me. I and my mechanic planned to change the head assembly (only engine) wd same AT gear. U guys can also suggest shd i go again wd same 1.3 or can put 1.5 or 1.6 aswell. Engine size, weight , bolts everything is same.just power is different. Suggestions pl.