Premium Octane?

[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....

[VStarRider]

I totally agree. I am on several forums with snowmobiles, another motorcycle forum (Star Bike Forums) with a few know-it-alls who dominate every thread, and often name calling is breaking out before the first page is filled with posts. Though Doo Talk (Ski Doo snowmobiles) is pretty good as well, probably a close second to this forum. I am in the middle of a discussion now on the decline of snowmobiling, very interesting. There are a lot of parallels between snowmobiling and motorcycling.

Anyway, I always enjoy the conversation and never respond with the thinking that I am going to change someone's mind. Just talking.

Things on my bike that probably would not be there without guidance from this forum:

Ragestad, Baker Wings, fog lights, and the biggest - doing all the maintenance myself!!!

For the record, I use:
Mobil 1 Racing T 10W 40 oil
Honda oil filters
87 octane gas
8,000-10,000 mile oil change intervals
Exedra tires
Pro Honda "Pledge" spray
Corbin seat

[F6Dave]

There's one more thing worth mentioning. A higher octane fuel than your engine needs can't hurt anything, but too low an octane can cause serious engine damage. So on older engines without engine management computers and knock sensors, it's safer to err on the side of more octane.

[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.

[1951vbs]

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.

Not sure your math is right...From your figures I calculate $.0715/mile on regular $.0789/mile on premium

[BIGLRY]

One thing I have not seen mention when talking about Octane numbers is the additives used by manufactures. You will find more additives in 97 Octane than in 87 Octane used for cleaning the engine's fuel system and help cut down bad emissions, but here is the rub. I have found engines that are designed to run on 87 Octane but are feed a steady diet of 97 Octane will have more deposits on the spark plugs over time due to the additives.

Is true there is technically more energy in 87 Octane than 97 Octane as the 97 is designed to burn slower in the higher compression engine. Even in the low compression engine say 9:1 if you put on a Turbo or a Supercharger you must run the higher octane if you are running boost and if you have a turbo Or Supercharger who don't twist up the wick once and a while?

All I'm saying is if you run high Octane fuel for feed for the steed then keep an eye on the spark plugs for crud build up and I'm talking about long time use.

[Kokomo Kevin]

Good info Larry, As usual. You are the King of Technical on this website, lest anyone else not think that!