best Fuel of whats available

[okcthunderguy]

Hey guys, i konw its probably not a huge diference on my stock '22 but im trying to learn what my best fuel is out of whats available around me. I always use 91 or 93 but Here in oklahoma, most places seem to be either 100% gas/no ethanol or possibly 10% at some places, but usually lower octane. theres one station around me that keeps 30% eth but they arent always close. any idea which is preferred if thats the only things available?

 

[TMac]

It depends on what you want to accomplish, and whether you're tuned.

For example if you want the best gas mileage, the 0% ethanol gas is best since there are more BTUs per gallon. However, in my location I also have access to 93 no ethanol gas- it's about 15% more dollar-wise per gallon which does NOT justify the extra .5 -1 mpg highway. A tuned engine is not going to show any measurable mileage gain- part throttle operation is based on spark advance, not airflow. The ST base algorithms are designed to try and optimize spark advance and as far as I know, you can't actually "tune" an effective "lean-burn" strategy.

In terms of performance, the higher the octane in an untuned engine, the better, but once again the difference between 91 and 93 is negligible and has much more to do with ambient air temperature.

In a tuned engine, where the boost pressure/air density can be increased, the increased cooling of ethanol additives (say a 93/10 mix) might actually be able to provide a bit more power than a 93/0 mix. You will be burning more of the former which makes up for the BTU content.

 

[okcthunderguy]

It depends on what you want to accomplish, and whether you're tuned.

For example if you want the best gas mileage, the 0% ethanol gas is best since there are more BTUs per gallon. However, in my location I also have access to 93 no ethanol gas- it's about 15% more dollar-wise per gallon which does NOT justify the extra .5 -1 mpg highway. A tuned engine is not going to show any measurable mileage gain- part throttle operation is based on spark advance, not airflow. The ST base algorithms are designed to try and optimize spark advance and as far as I know, you can't actually "tune" a relevant "lean-burn" strategy.

In terms of performance, the higher the octane in an untuned engine, the better, but once again the difference between 91 and 93 is negligible and has much more to do with ambient air temperature.

In a tuned engine, where the boost pressure/air density can be increased, the increased cooling of ethanol additives (say a 93/10 mix) might actually be able to provide a bit more power than a 93/0 mix. You will be burning more of the former which makes up for the BTU content.

Thank you for this. I couldnt quite grasp what role the ethanol was playing in there. very much appreciate the explanation.

 

[Mirage]

87 from Costco. Runs great. But I'm also not racing anyone.

 

[I Bleed Ford Blue]

The ST's can handle an E30 mix from the from the factory, but you won't see much gain until you get tuned.

 

[Toadster]

also, when you get gas - there is a difference https://www.autolist.com/guides/top-tier-gas

 

[Cmaximst]

93 from Costco runs even better!