ayau
Senior Member
I believe on the factory tune, there's a little ignition retard on 91 octane. If you run 93 or higher, then you'll have 'maximum' power from the factory tune.BS. The factory tune is tuned for 91 octane and adding additional octane won't do anything.
As far as I'm aware there's no realtime octane sensor manufacturers can just shove in the fuel line like an ethanol sensor.
Go to 15:20 where he talks about the tune being universal and the only difference being the octane where the car is being sold. UK has 98 RON, which is about 93.5 AKI (US octane).
Furthermore, Hondata said the factory map is tuned for 0% ethanol. In the US, nearly every station has 10% ethanol. The 91/93 Hondata maps adjusts the tune to account for the 10% ethanol by adding additional fuel. If this isn't adjusted, the factory fuel trims will probably always add a few percent short/long term fuel to reach stoich. This further supports that the ECU was tuned with UK gas, which ethanol isn't as prevalent.
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