Race gas octane info....

[Mopard]

I have a question concerning the mixing of different octanes. I have 15 gals. of 93 octane and I have mixed it with 6 gals of 111 oct. race gas . What has that raised my octane to? I have talked to several people and they can not help.

[ehostler]

That would be an approximate 98 octane.

[cuda451]

wouldn't it be 100.2 octane?

6/15 x (111-93) = 0.4 x 18 = 7.2 add that to 93; gives 100.2.

a 50/50 mix would give 102 octane, right?

[ehostler]

As it is a total of 21 gallons, wouldn't the correct equation be -

6/21 = .286 X 18 = 5.14 then add that to 93 for a total of 98.14?

Another way to look at it is straight up averages. (15*93)+(6*111) = 2061 / 21 = 98.143

[cuda451]

You're right; I wasn't thinking of the sum, just a portion of it!

[Mopard]

Originally Posted by ehostler

That would be an approximate 98 octane.

Thanks for the info. I do not know how to figure it up but I would have guessed it would have been higher than that.

[Mopard]

Originally Posted by cuda451

wouldn't it be 100.2 octane?

6/15 x (111-93) = 0.4 x 18 = 7.2 add that to 93; gives 100.2.

a 50/50 mix would give 102 octane, right?

That is what I would have guessed around 100 to 102 octane. But what do I know. That is why I asked the question here.

[Mopard]

Originally Posted by ehostler

As it is a total of 21 gallons, wouldn't the correct equation be -

6/21 = .286 X 18 = 5.14 then add that to 93 for a total of 98.14?

Another way to look at it is straight up averages. (15*93)+(6*111) = 2061 / 21 = 98.143

So what would it have been if it was a 50/50 mix, of 10 gals 93 and 10 gals of 111 oct?

[cuda451]

50/50 would give 20 gals of 102 octane.

[rumblefish360]

I'll be the sour grape here and write........

Didn't some years back the mixing of two lower octanes give the mixed result of more octane than the two started out to be and (As I heard) end up higher than the high octane fuel at the pump?

Also, I'll be honest, I really do not think straight math will work on this mixing of fuel and octane result.

[cuda451]

I may be assuming too much, depending on formulation, compatibility, etc., but I'm thinking in the simplest blending sense that this weighted average approach gives the correct answer. (In the same way that Sunoco could offer several octane levels by mixing 104 with the lowest grade proportionately.)

[Mopard]

Originally Posted by cuda451

50/50 would give 20 gals of 102 octane.

Thanks for the info. It is too bad it would not be of higher octane, especialy with the mixing of the 93 and the 111 I spoke of. Because of the price I paid for the 6 gals of 111oct when added to the 93 it only makes it 98oct. It would have been cheaper I guess to have purchased 100 oct in the first place. But I did not find this gas station until after I already had so many gals of 93.

[Mopard]

Originally Posted by rumblefish360

I'll be the sour grape here and write........

Didn't some years back the mixing of two lower octanes give the mixed result of more octane than the two started out to be and (As I heard) end up higher than the high octane fuel at the pump?

Also, I'll be honest, I really do not think straight math will work on this mixing of fuel and octane result.

I kind of wondered if the two octanes would mix properly when just added to the tank that already has the many gals of 93. I mean you are only just pouring 6 gals of 111 into a tank that has 15 gals of 93. No shakeing or stireing at all.

[Mopard]

Originally Posted by cuda451

I may be assuming too much, depending on formulation, compatibility, etc., but I'm thinking in the simplest blending sense that this weighted average approach gives the correct answer. (In the same way that Sunoco could offer several octane levels by mixing 104 with the lowest grade proportionately.)

??? Well that one confused me.

[ehostler]

Without know all of the variables, the weighted average is the only method that you can really use. Heck, gas stations already do that. They only stock low grade and high grade gasoline. They use a mixer to give you the mid grade. Again, they are using a weighted average.

As far as mixing the fuel goes, you will get some mixing action, when pumping in 6 gallons on top of 15. It just won't be the most even mix. After a few miles of driving, it should get a fairly complete mix.

[Mopard]

Thanks for the info. I did not know that. So I guess that the mid grade is just a mixture of the high and low grades.
Another question, does octane booster realy boost the octane numbers, also which oct. booster would be the best.

[ehostler]

Octane booster aren't worth the money. When they say that it will increase the octane by 1 point, they don't mean from 93 octane to 94 octane. They mean from 93 octane to 93.1 octane. You need to ad an awful lot of octane booster to get from 93 to 94.

The best thing that you can do is adjust your timing and fuel fixture. If you are building and engine, then you can build it right and be able to run current pump gas and loose little or no power.

[Mopard]

Thanks for the info. I kind of figured that. So I guess the 104+ octane booster is in the bad list also?

[2 DART]

what are you running the gas in?

[rumblefish360]

Welcome to the site 2DART. (Wheres New Germany?)
I think the question was a "In general" one.

[Mopard]

Originally Posted by 2 DART

what are you running the gas in?

69 R/T Charger. 440 car

[Mopard]

Originally Posted by rumblefish360

Welcome to the site 2DART. (Wheres New Germany?)
I think the question was a "In general" one.

Good question rumblefish360. I never really paid that much attention to where people are from.

[Mopard]

Would I need to change plug gap or go to a colder plug useing a 102 octane?