Quote:
Originally Posted by Vezna31
Well, I definitely felt enhanced performance on 100% 100 octane the day after my track day. The response was instant and the car just wanted TO GO. I drive the car enough to know when there s a difference.
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Your computer must have been able to advance ignition timing a few degrees. Energy in gasoline is measured in the form of BTUs.
-87 octane gas usually has a BTU content of ~114,000-115,000 BTUs/gallon.
-93 octane gas usually has a BTU content of ~110,000-111,000 BTUs/gallon.
-For reference, diesel gas has a BTU content of ~146,000-148,000 BTUs/gallon.
The only ways higher octane gasoline can increase power are to either raise compression (boost) due to higher octane gas resisting detonation (burns slower), or advancing ignition timing (slower burn therefore advancing timing will result in a longer, more efficient power stroke).
Comparing 87 to 93, 87 has a higher energy content. Not changing timing, compression, and other factors (temperature, etc.) will result in 87 octane gas producing more power in an engine. However, 87 burns faster therefore resulting in limited compression and a shorter power stroke limiting timing advancement.