The master mechanic is talking about an otto cycle engine. We have a miller cycle engine which has the s/c not for boosting performance. It is very complicated and i dont have the exact answer. The manual suggests 91 US-octane, premium is 93 oct here. And this is for worst case. So I mix 93+89 for summer and 89 for winter. ECU compansates timing if it detects lower-than-required octane fuel anyway.
And higher octane is kind of reluctant to burn thus doesnt burn totally. Thats why you would have low power with high octane as far as low octane fuel doesnt cause pre ignition. The unburned fuel collects on catalytic converters (i.e. carbon build-up) and your cats are death.. High octane burns slower, low octane is more aggressive causing more force on pistons and other parts.. However on both rock solid engines this is not an issue to be considered..
Quote:
regarding need for premium fuel, master mechanics advise that if you own a supercharged car or
one with high compression (10to1 or higher), you must use premium to avoid spark knocking and burning of piston heads. On the other hand, for a non-supercharged or lower compression engine, using premium fuel is a pure waste of money and will carbon-up the engine. Use whatever the car manual recommends![/b]
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