MikeFreas
Well-Known Member
- Joined
- June 23, 2011
- Messages
- 301
- Reaction score
- 2
- City, State
- VA Beach VA
- Year, Model & Trim Level
- 2012
Breaking it down nerd style.
Modern turbo charged engines will run on even the worst fuel (like in CA) but you are correct in that performance suffers. When you fill up with 87 octane fuel the engine will most likely have pre-ignition under boost and or load. The knock sensors will “hear” this and retard the timing and/or richen the fuel mixture to prevent the knock depending on the ECU’s programming. Some manufactures (like Mitsubishi) program there ECU’s to go into “limp mode” after a set amount of time the engine hears knocking. Both retarded timing and richer fuel mixture will hurt the MPG and performance but saves the engine from damage. Most cars you really can’t tell the difference other than filling up more. I owned a highly modified Eclipse GSX for 12 years and could tell when the timing was being pulled due to knock or high inlet temperatures.
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