It is interesting, especially this bit: "When the fuel is injected directly into the combustion chamber, it dilutes the oil film lining the cylinder. This fuel dilution reduces the surface tension and viscosity of the oil, causing an oil-fuel mixture to accumulate in the upper reaches of the piston top land crevice. The mechanical energy of the upstroke during compression pushes droplets into the combustion chamber, where they vaporise and can auto-ignite prior to spark ignition."
To me, this implies it's a combination of direct injection (i.e. not 'conventional' throttle-body injection) and a high CR causing 'dieseling'
It'll be inetersting to see how Mazda's much vaunted HCCI engines fare when they arrive on the scene in 2019, given they are effectively using diesel technology in a petrol engine. Mazda need to be REALLY careful here, as they have currently, in my view, got a customer perception problem with their diesel engine reliability, and if that expands to their petrol engine range, then that could mean REALLY BAD porblems from them, given they are no longer jointly owned by Ford and as such don't have the finanical clout to withstand a VAG style PR nightmare.
Many YouTube videos regularly show how poor a state many DI petrol cars valves are compared to 'old style FI' ones after 30-50k miles, and the problems that result, plus the need for them to be either replaced or cleaned, both of which are not cheap.
It seems the tech is reducing costs in terms of better mpg (for a while) but then loading far more up as parts wear out quicker (apparently this issue also reduces mpg when it gets bad) due to (IMO) inherrant design flaws in the concept of DI petrol engines. You have to wonder if the manufacturers are doing this deliberately to get more post-sales custom.
|
