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#1 |
Join Date: Nov 2018
Location: Washington
Posts: 98
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In my area, I have three choices of gasoline, Ethanol based 91 octane, non- ethanol 87 octane, and 100LL Avgas. Which would be the best fuel to use in my stock '91 LT5 that doesn't get driven a lot? Which fuel lasts the longest in the tank?
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#2 |
![]() Join Date: Jun 2013
Location: PA
Posts: 879
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Ethanol based 91? Or 91 octane with ethanol? "88 Octane" is E15. So I'm guessing you mean regular 91, but with ethanol. Typically 10% or less. That is the best choice, with replaced injectors. Original injectors are not ethanol compliant. Non-ethanol 87 is on the low end for the high compression ratio. 100LL is not only not legal to run, but extremely costly and will damage your catalytic converters over time.
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#3 |
Join Date: Nov 2018
Location: Washington
Posts: 98
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Yes, I mean regular 91 octane with ethanol. My injectors have been replaced with Jerry's FIC units. I don't have cats on the car as this motor is in a 67 Camaro. The problem with ethanol gas is it doesn't stay good for long. I've been running non-E gas in my other collector cars and equipment without issues.
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#4 | |
![]() Join Date: Jun 2013
Location: PA
Posts: 879
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#5 |
Join Date: Jun 2012
Location: fort worth
Posts: 183
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Since you replaced the injectors, I'd say run the 10E 91 octane pump gas.
100LL is one of the best storage fuels, but the lead will kill the cats and eventually foul the o2 sensors. I blend 87 non-ethanol and 100LL for my C3 big block. Last edited by CamP; 05-26-2022 at 02:23 PM. |
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