Originally Posted By: badtlc
Originally Posted By: gathermewool
Why not 87 octane? V-Power is only offered in the highest octane, right? Around here, that's 93. If that thing calls for 87 AKI, what's the benefit of using multiple tiers higher?
This has been covered many times but modern engines, especial DI engines have the ability to control AF ratio in addition to timing based on octane. If you run premium in a skyactiv, it not only advances timing but leans out the AF ratio which improves MPGs and reduces fuel dilution in the oil.
When running 87 in such a high compression engine, the ECU has to run pig rich to keep the combustion chamber temps down and prevent detonation. It works fine but there are better options if you prefer.
doesn't it all depend on the engine management system. What about compression ratio, flow, valve overlap...? I was told most ECU's pull ignition timing and throttle position to stop knocking. ?