Premium Octane?

[F6Dave]

When it comes to mileage, what matters is how much energy is in the fuel you use. Here are a few numbers:

Diesel #2: 129,500 BTU/gal
Regular gasoline: 114,100 BTU/gal
E10 gasoline: 111,836 BTU/gal
E85 ethanol: 81,800 BTU/gal
Pure ethanol: 76,100 BTU/gal

The numbers say that ethanol free regular (87 octane) gasoline has about 2% more energy than an E10 blend. So you should see roughly a 2% improvement in mileage by switching from E10 to pure gasoline. That's less than 1 MPG in my case, and given the normal variations in my mileage I haven't really noticed a difference.

BTW, 91 octane premium actually has slightly less energy content than 87.

[Big TP]

Its not what you think.....this mornings price at my local store: $2.93 for 87 octane unleaded and $3.47 for 91 octane ethanol free premium. If you do the math and use a 6 gallon fill up, it will cost you $17.58 for regular and $20.82 for premium. If I get 41 mpg on unleaded, I'll get a 246 mile ride for my 6 gallons. For the same 6 gallons, I'll get 264 miles at 44 mpg for the premium. Break it down to the per mile fuel cost and it costs me $0.1399 per mile for unleaded and $0.1268 per mile for premium so.....Its cheaper for me to run the premium, get better mileage and what I perceive as better performance.

I may be wrong but looking at your numbers it seems you spent $.3.24 more on the Premium fill up and got 18 more miles?
If that's right than the 87 octane would be cost efficient, of course not taking into account perceived performance improvements.
Most Respectfully,
TP

[3Chief]

When it comes to mileage, what matters is how much energy is in the fuel you use. Here are a few numbers:

Diesel #2: 129,500 BTU/gal
Regular gasoline: 114,100 BTU/gal
E10 gasoline: 111,836 BTU/gal
E85 ethanol: 81,800 BTU/gal
Pure ethanol: 76,100 BTU/gal

The numbers say that ethanol free regular (87 octane) gasoline has about 2% more energy than an E10 blend. So you should see roughly a 2% improvement in mileage by switching from E10 to pure gasoline. That's less than 1 MPG in my case, and given the normal variations in my mileage I haven't really noticed a difference.

BTW, 91 octane premium actually has slightly less energy content than 87.

Information like this that people post is one of the things I love about this board. I'm continually amazed and further educated by the knowledge that is shared here.

[tenxxx]

When it comes to mileage, what matters is how much energy is in the fuel you use. Here are a few numbers:

Diesel #2: 129,500 BTU/gal
Regular gasoline: 114,100 BTU/gal
E10 gasoline: 111,836 BTU/gal
E85 ethanol: 81,800 BTU/gal
Pure ethanol: 76,100 BTU/gal

The numbers say that ethanol free regular (87 octane) gasoline has about 2% more energy than an E10 blend. So you should see roughly a 2% improvement in mileage by switching from E10 to pure gasoline. That's less than 1 MPG in my case, and given the normal variations in my mileage I haven't really noticed a difference.

BTW, 91 octane premium actually has slightly less energy content than 87.

Why do drag racers use high octane?

Its all about the conversation.
Many different ways to justify your reasoning.
Many informative ideas and opinions.
Thank GoD for giving us all different perspectives on things.
A good thread where theres no, I'm right and your wrong.
What ever makes you Happy, Happy, Happy,,,,,,

[Kokomo Kevin]

Amen brother! If you didn't know you do now, if you didn't care you might now. Nothing like a damn good conversation, winters coming probably going to have few more before next spring....

[Big TP]

91 'above' 86
So, you're good!

Cheers,
Steve

Yes Sir, Like the book sez, 86 or above . So 87 is what I will be staying with until otherwise necessary.