Quote:
Originally Posted by SuperSnake1972
The reason you're not finding any 93 octane is because of the higher elevation. And the onboard computer adjusts for both the elevation and octane rating.
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91 octane is prevalent in the SW because NA engines make less power at altitude (lower effective compression rate).
When I lived in Deming, NM (4300 ft elevation) 87 wasn't available at most stations. The choices were 86, 88 or 91 typically.
In the Tucson area (22 to 2300 ft elevation), a NA engine is down roughly 6% in power (rule of thumb is 3% per 1000 ft). Boosted engines are a different story of course, keeping the knock sensors busy.