Quote:
Originally Posted by Fetch
I would expect the car would actually not run well on premium. A fuel's octane rating it its resistance to combustion. A fuel with a rating of 93 octane will be harder to ignite than a fuel with an 87 rating. Since the engine has such a lean air/fuel mixture in lean-burn mode, Honda actually designed it so that one of the intake valves will only open a smidge to let fuel "dribble" in and ignite near the spark plug. Otherwise, the mixture would be too hard to ignite. I am unsure if the car would run well in lean-burn mode with a higher-octane fuel.
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Hi Fetch,
I would like to correct this. The octane numbers mentioned in this thread are extremely low. In Europe 95 octane is the LOWEST octane rate you can buy. 98 is also available. The Vtec-e engines were also sold in Europe, without any problem to ignite the lean mixture.
The octane rate is indeed as you mention the resistance to self combustion, but it does not mean a spark plug wil have any problem with a very high, or even extremely high octane rate (>100 is used in racing). The octane rate is resistance to heat and pressure caused ignition, not to spark-ignition.
Of course, a spark will have difficulties with igniting an extremely lean mixture, but this is independant of the octane rate.
By the way: I filled (and still fill) all my cars and motorcycles with the lowest availabel octane rate (95 in Europe). No problem at all.
If Honda says it runs on 87: i would buy this fuel for my car.