Ok here in Washington we have 92 octane at the pump, I have a 76 station 30miles away that sells 100 octane unleaded race fuel. Expensive stuff but my thought was to boost my octane to about 95-96 octane for a nice boost in HP with the stock setup. The EVO has a 14 gallon tank what would the math formula to obtain 96 octane mixing 92 with 100 octane. Anyone know the basic formula for this equation math is not my strong suite.

 

I forgot who posted it but a memeber from this forum posted an equation. Try searching for it under "toulene....octane....."

-randy

 

OK did a little digging its pretty simple... "An alternative path to octane euphoria is to blend gasolines of different octane levels yourself. It's easier than you may think, safe, and the results are predictable. The formula for mixing gasolines of the same type is pretty straightforward. When you mix a 50/50 blend of two unleaded fuels, simply average the two octane ratings to determine what's in the tank If you mix 94 and 100, you get 97. The same generally holds true for leaded gasolines, assuming the lead content is nearly equal."

 

Rather than drive 30 miles all the time, why not buy a 55 gallon barrel of 100 octane gas (probably $150-175), and mix your own stuff at home?

 

Well that woulds be cool but unfortunatley its $6.20 a gallon! ( I just called) and I dont have a truck or anything to haul a 55 gal. drum unless I rent something, plus they pump it out a really big drum so expensive anyway you dice it. I was thinking of buying a couple metal 5gal. and fill them up and do a 6gal. to 5 gal. mix, plus fill up when I am there that should limit the trip to once a month.

 

Do you guys retune your engines or run higher boost to take advantage of the higher octane?

Last time I checked, running higher octane by itself gave no benefit, except to make the fuel harder to auto-ignite.

 

Yes this is true, in my young years i worked at a gas station and most if not all do not even have seperate tanks for mid grades. If a stations lowest octane is 87 and highest is 97 then they will have a 87 tank and a 97, if you select 89 the pump will simply combine the two at the correct ratio to achieve the mid grade. So it would not be hard to do yourself. Unfortunately the station owner where i worked was rather unorganized and we would frequently run out of 87, which would effectivly put us out of all mid grades, in turn a lot of customers just pumped premium just because they were too lazy to go some place else. Funny watching a Geo tracker fill up with premium.

EDIT: while on the subject, the myth that all gas is the same is not true, getting gas from a Texaco for instance would provide a much cleaner fuel than that from a no name station which generally runs a generic fuel. Of course its all additives, but non the less its at least best to always run the same "brand" gasoline in my opinion.

 

Ok, a simple formula that I use is as follows:

( octane * gallons ) + (octane * gallons)
---------------------------------------------------
total amount of gallons

for example,

Let's say that you want to mix 5 gallons of 93 octane with 2 gallons of 117 octane race fuel (such as VP C16).

(93*5) + (117*2)
----------------------
7

465 + 234
-------------
7

699/7 = 99.86 octane

Remember that this is approximate and assumes that both octanes are meassured the same way (ex. (R+M)/2 ), but you get the idea.

 

Fuel Mixing Octane Calculator

 

Wow that is one great site thanks, forums are a true collective think tank

 

You will have a tough time figuring out how much fuel you have in your tank. The fuel level gauge is quite deceptive.

What I do is drain out all the pump gas that is in my tank before putting in a few gallons of race gas. There is more to race gas than just octane. I'd much rather just run the pure stuff when it counts.

You can drain your fuel tank by removing the fuel return line from the end of the fuel injector rail. Then hook up a 6 foot piece of fuel line to the fuel pressure regulator. Run the other end of the line into a gas can. Then either turn on the fuel pump (I installed a switch to do so) or just run the car until it starts sputtering.

 

Great link. Thanks.

 

very cool, thanks!