Is there a formula to determine what the octane rating is when you add different octane gas in the tank? Let's say I add 15 gals of 93, and 5 gals of 109 in my 20 gal tank. What would that raise the octane level to ?

 

((15*93) + (5*109))/20=97

 

Try (x*a)+(y*b)/(x+y)

x=gallons of octane a
a=octane of x

y=gallons of octane b
b=octane of y

If you have 5 gallons of 93 octane and 7 gallons of 97 it'll be something like:

(5*93) + (7*97) / 12

 

Just make a simple average account...Smoking got it right.

You should, on my opinion, also consider the quality of the gas you're mixing, i've always mixed gas, adding 98 premium pump gas to 105 race french gas...on top of that i've always liked to mix some oxigen additive to help a quicker combustion.

If you add a low oct poor quality gas in a good quality race high oct gas, you'll probably end up with a high octane poor mix anyway.

 

i figure it to be 97. I am not a math wiz but if you add 5gl of 109 to 5gl 93 the you are adding 16 degrees of octane which would then be reduced by 1\2. So every time you add another 5gl you would increase the the number you divide with by 1 so for 10gl it would be 3 and 15gl it would be 4. 16 divide by 4 equals 4 added to the 93 octane gives you 97. Check my thinking when you add 15gl of 93 and 1 of 109 you are really spreading 16 degrees of extra octane over 20gl of 93 octane gas the 15gls of 93 plus the 5gl of 109 which is 93 plus 16. I am not a chemist either but I am a chef and bartender and have converted recipes so I think this would work

 

simple math

 

On that account, what about octane boosters? I've seen them, but would anyone recommend them? I don't have many race fuels available around here... Not to mention it's a street car anyway, but 93 isn't cutting it unless I drop timing.

 

NO to octane boasters, waste of money. they only raise few points, ie tenths, not a full point so you might go from 93.0 to 93.5 if you were lucky.

 

Go for a good race fuel mix if you want to improve your oct no...also, usually, these fuels are a much BETTER quality (and refinement) then pump gas, so you're not only improving oct no. but also the quality of the gas you're feeding into the engine.

 

I haven't tried this yet, but I plan to experiment with the lead additives. Max Lead 2000 claims that if you add 48 fl. oz. to 20 gal. it would give you an approx. octane # of 103.

 

You're better than a chemist! Thanks

BTW, what's in a Screaming Viking ?

 

I'm game to trying this stuff. I notice on their chart that if you add only 24 oz. to 20 gals, it raises it to 101. That's half of the 48oz to get it to 103. I would think 101 would be plenty. It would be nice if this stuff really did the trick, as buying 5 gals of racing gas every time I fill up, isn't that convenient and at $10/gal for 109, a little pricey!
Max Lead is $30/gal, so it would be more economical, IF it works. I'll let you know.

http://www.maxlead2000.com/

 

I bought a case a couple of years ago and use it from time to time. It actually works!

 

Please do let me know how it works out for ya! I was planning to run a mix of about a quart (32 oz.) to 16 gallons. Hopefully, that would bring me close to 103 or better. It would be the cheaper alternative. If you by 6 gallons at $28.00 with the mix I plan to run, it comes out at about 44 cents a gallon give or a take a little. 93 where I live is about $3.27 at the moment. Add 44 cents that's about $3.71 a gallon for 101-103. Back in the summer, I believe 103 was about $7+/gal and the 110 was$9+/gal!

You've got me wanting to place an order.. I hate running on retarded timing!

 

Mixing different grades of gas for octane isn't that simple. Since US gas is rated by the (R+M)/2 method what your really want is to find fuels with the highest Motor Octane Numbers (MON), as that's the value that matters most in the real world under the hood. Thing is, it may be possible that one brand's 92 is actually of higher quality than another's 93. (...but, which one do you think likely sells more, and at a higher premium price??)

For example; mixing an inferior grade of 93 which has a 98 Research Octane Number (RON) and an 88 MON with a 109 which has a 112 RON and a 106 MON may yield an average octane of ~97, but the MON would only be ~92.5. Doing the same mix with a better quality 92 octane pump gas, say with a 94 RON and 90 MON with the same 109 would yield an average of only ~95.5, but a higher MON of ~94. (Note that these numbers are purely hypothetical for the sake of the point.)

And yet, it's more complicated still, as the blend's true octane will depend somewhat on chemical properties beyond the raw math.

FYI, the findings may not be quite up to date now, but Vizard published how a good number of brands stacked up in "How to Build Horsepower, Vol. 2" for those interested. (I'm not brave enough to go there myself.)

HNY!

 

Blending synergies are nowhere near lineral.

Refinery worker here. It's amazing what you can do blending.

10% ethanol will raise octane about from 84 to 87.

We use polymerized and reformed stocks to get higher octane. Butane really gives a good kick. Hard to blend at home though.

Generally, adding a smaller amount of higher octane gas will give you a higher than "averaging" result. 5 gallons of 92 with 15 gallons of 87 wouold probably yield about 89-90 octane.

But the only way to find out the resulting octane is to run it on a "Knock engine" against a standard, very expensive, and no we don't allow anything from outside the refinery to be run on ours.

To answer your question about the blend you asked about. Depends on the chemical make-up of the blendstocks, what's in the 109, TEL ?

 

I was wrong on the octane: it's 104 MON rated, not 109. It's VP brand C11. But, it is leaded fuel.

 

There is only one worth considering, and that is Torco Mach Series Accelerator (Race fuel concentrate, whatever that is). Exactly how it raises the octane so much with a small volume seems to be a proprietary secret. According to some analysis I've discovered 1 quart to 15 gallons raises 91 (CA, Chevron) Octane to about 93 Octane. This is based on the chemical analysis one guy sent out to have done on before and after samples, and it matches my personal experience. I used to mix Toluene with 91 to make about 93 (simple averaging), the point at which my engine stopped pinging and occasionally detonating (I have a high compression motor). It's not exactly scientific, but now just roughly 1quart of Torco and I'm good to go

As mentioned above, it is pretty complicated for sure. I know we have several special seasonal blends here in CA. Summer is borderline worthless as far as I can tell. The winter blend seems to be rather better for making power. But that's just my anecdotal impression.

Anyway, Torco is worth a shot if you need to kick up otherwise regular Premium gas. It honestly worked like a charm for me. But if you need race fuel, you need race fuel.

 

I am not a math wiz so just put the good stuff in an run it

I ran 110 turbo blue in my boat last year in a blown 1200hp 540 and it worked great! Sure it was $5.25 a gallon but I could drive 15 min from home to a station that carried it and fill up some cans for later on.

When you spend the money I did on a motor like that buying the good gas is a no brainer, kind of like changing your oil allot its cheap insurance

 

I currently run 93 + VP racing fuel and have had some of these same questions. Comments I have heard:

Mechanic #1 - don't use aviation gas as combustability is different than car engines require. Don't use leaded additives or leaded racing fuel as it fouls my valves more quickly and is bad for the environment to boot.

Mechanic #2 - only use low lead aviation gas (I think 101 low lead is available from your local civil aviation airport for $4/gallon) as it blends well with pump fuel and is stable (does not gum up easily). Never use additives or VP fuel. He claims they do not mix with pump gas and gum up quickly if it is not a daily driver.

I'm not sure who to believe, but I'm thinking of switching from a VP blend to an av gas blend.