As someone for whom Harry Ricardo was close to a deity in my formative years, I would remark that sleeve valves were developed as a way of reducing NVH and service intervals for engines, so at the time made sense. The problem is that it is very difficult to make a sleeve valve Diesel because the ports are in the walls, which limits the compression ratio. The other problem with SV engines is the trail of most un-RR like smoke. They would possibly have done better to do a 2-stroke Diesel with blown scavenge, like a marine engine, but Harry R did love his sleeve valves.
But, let’s face it, once they were using cheap truck engines, albeit with good balancing, RR Motors as a car company was pretty much window dressing, like one of those iPhones with the back covered in Swarovski crystals that they sell to Chinese businessmen in Harrods.
