Question about mixing different fuels/gases

[99LRDblaster]

So I went out today and picked up 2.5 gallons of Sunoco(Cam2) 110(leaded). My compression is a bit high, but it doesn't warrant THAT big of a jump, but it's the only fuel higher than 93 octane around here. Anyways, I mixed the 110 octane with the 93 premium I had. It's mixed at about 65%-110/35%-93.

My question is this fine?.....will it actually help the pre-deflagrating I've been having? I'm no expert on fuels, but part of me thinks that the 35% of the 93 octane would just pre-deflagrate like it already does and once that deflagrates, it would deflagrate the remaining 110.......essentially making the 110 worthless. Would I be wrong in this presumption? :-/ I hear a lot of people say "Well I run 110 octane mixed with 93 octane, so I'm running 100 octane", yet that just doesn't seem to make sense to me as it just seems as if it's 2 separate fuels mingling amongst each other but still with completely separate characteristics. I guess I'm just interested in what your thoughts are.

 

[Surfrjag]

well from what i understand they dont mix.. i mean lots of people do it but talking to this scientest guy he says the molecules dont mix so in my opinion it may help but run one or the other not mixed.

 

[99LRDblaster]

well from what i understand they dont mix.. i mean lots of people do it but talking to this scientest guy he says the molecules dont mix so in my opinion it may help but run one or the other not mixed.

Nevermind. I think I answered my own question.

Based on what I understand(might be wrong), but most conventional gases are put on a specific octane rating on the amount of n-heptane and octane isomers in the fuel. So while 93 may run less octane isomers? than 110, they are still the same molecules.....just in different proportions. Therefore when you mix them, you are able to get the average of the two for octane when you mix them 1:1. That's makes sense to me based on my chem background. It does raise questions on how these volatility and deflagration of fuels are controlled though at different compressions to begin with though. :-/

My only question then is if the leaded gas will mix with the unleaded gas. I'm not sure if the lead additives in the 110 are actually attached any of the fuel molecular structures or if they are simply in the same solution. Time to bust out the chemistry again.

 

[sheeblast]

ask this question, what makes gas 93 AKI?
gas is a mixture of different things. so really yes, you can mix gas, but it isn't as simple as saying 50% of 110 race gas and 50% of 93 pump will give you 101.5 octane rating. you need to know what anti knock agents are in each gas and use that to find the AKI.

 

[99LRDblaster]

ask this question, what makes gas 93 AKI?
gas is a mixture of different things. so really yes, you can mix gas, but it isn't as simple as saying 50% of 110 race gas and 50% of 93 pump will give you 101.5 octane rating. you need to know what anti knock agents are in each gas and use that to find the AKI.

Well in this case it would be lead......and/or maybe something else. The lead will be diluted by almost half since it will be in unleaded. As a raw octane average I am coming out to 103/104, but if the leaded fuel is being diluted by 35%, then I believe it would be 35% less than 110-93=17......so 17x0.65(for 35% less lead in dilution)x(0.65 for 65/35) mix would give me 7.2+93 octane, so roughly 100 octane. I realize this is in the hypothetical world and there is a lot more to it in thermodynamics of how the mixed fuels combust, but that's what I'm assuming you are getting at.

At any rate, the octane level should be higher with the two mixed and both should deflagrate at the same time since it is now a homogeneous mixture. What is the exact octane with 110 leaded mixed with 93 unleaded at a 65/35 mix?.......nobody really probably knows that for sure unless we go to a lab with some scientists.

 

[lasxgames]

CAN I MIX RACE GAS WITH PUMP GAS?
Yes. Lots of riders do it to save money. But don't think of it as improving the quality of pump gas, it's more like diluting the quality of the race gas. The main caveat still remains, however: if your engine doesn't need race gas, it probably doesn't need a half-half mix either. Unless you have an unusual octane requirement and are on a tight budget, it's best to run pure race gas or pure pump gas.
links
Gas fuel information
http://www.blasterforum.com/engine-13/fuel-blending-calculator-36495/
http://www.blasterforum.com/engine-13/gas-fuel-information-13887/
links

 

[sicivicdude]

Gasoline is a mixture of about 85 different petro-chemicals. The base blend stock is made up of the hydrocarbon chains C2-C24 (bunches of 'enes and 'anes in there)

"Base fuel blend stock" is used for pretty much every type of gasoline made and then an additive package is mixed into it to create the octane grades and branding for each manufacturer. The additive package may constitute up to 50% of the mixture by volume (so it's not an additive as you would normally think, just a small portion of the volume)

Avgas uses the same basic blend stock but the additive package varies wildly, notably tetraethyl lead but also some of the other components. Race gas can either be a normal blend stock plus a specialized additive package or a custom base stock depending on the manufacturer. You can normally tell the difference in the price tag. The custom blend stocks are cracked at small refineries to a higher purity by more closely controlling the condensation temperature the blend stock is captured at. The stuff that's over $10 a gallon is usually the custom blend stock stuff...

Also, tetraethyl lead is soluable in hydrocarbons no matter their origin. The lead will blend with 87 octane gasoline if you poured it in there so no problem with mixing.

 

[99LRDblaster]

Yea, I went out just now and started it up with the 103....ish....octane mix. Probably a little higher than I need as 98-100 octane would probably suit my needs better, but it sounded a hell of a lot better. No more metal hammer hitting kettle bells sound. Throttle response was VASTLY improved. Compared to the straight 93 that would bog a lot when I gave it gas, this has instant response. Revs don't hang as much as they did before.

I can tell the jetting is off though. I bumped up one main to 260, but probably need to go up to 270. I couldn't tell much because it's nothing but a sheet of ice in Ohio and I was in 4th gear and going about 15mph.

I'll have to wait until I get a dry day to see the difference in power.....seems pretty spunky though considering I was just spinning the tires the whole way.

 

[jayflight]

i have a question considering octane ratings and the mixture of 2 cycle oil. when normal pump gas (87 octane) is contaminated with even a slight bit of standard motor oil, (example: a leaking intake valve seal on 4 stroke) it starts to drop the octane rating. in some cases enough to cause a ping or pre detonation in sensitive engines. what effect does 2 cycle oil have on octane and is it formulated to reduce this effect? if it does in fact lower the octane rating, then would a higher ratio, say 50:1 to 100:1 with a premium oil be far better for the piston and crank stress vs. the improved bearing lubricating characteristics of say 32:1? if so whats the difference between synthetic and conventional mixing oils for this effect?

 

[Paulie B]

i have a question considering octane ratings and the mixture of 2 cycle oil. when normal pump gas (87 octane) is contaminated with even a slight bit of standard motor oil, (example: a leaking intake valve seal on 4 stroke) it starts to drop the octane rating. in some cases enough to cause a ping or pre detonation in sensitive engines. what effect does 2 cycle oil have on octane and is it formulated to reduce this effect? if it does in fact lower the octane rating, then would a higher ratio, say 50:1 to 100:1 with a premium oil be far better for the piston and crank stress vs. the improved bearing lubricating characteristics of say 32:1? if so whats the difference between synthetic and conventional mixing oils for this effect?

Good questions. I have no answer but the Q's are good none the less.....
I have noticed in my travels that syn oil doesn't like to burn and is more likely to run out the back and clog up your silencer.
I'm not saying don't run synthetic oil cause I do, just noticed this happening over oldschool oils.

 

[biggrobb762]

so is it ok to run 110 gas with 32:1 mix

 

[Paulie B]

Yeah man nothing wrong with that.

 

[biggrobb762]

so will it give you more power or less engine life

 

[darederek]

It was proven that 2 strokes run the best at right around 18:1 and if you don't believe me I can find the article but it isn't economical. 32:1 really is the happy medium

 

[Paulie B]

so is it ok to run 110 gas with 32:1 mix

Unless you have the mods to take advantage of race gas like higher compression, advanced timing, you are wasting your money.
If you do have high compression then you will have a shorter amount of time between re-builds namely the bearings.

 

[Paulie B]

More oil never hurt anything but you also have to consider that the more oil you add to your pre-mix makes your jetting that much leaner.
For example using the same oil, changing from 50:1 to 18:1 without re-jetting would be a big mistake that best case would end in fouled plugs, worst case piston seizure.

 

[York Racing]

I run 50:1 with VP's U4.2 when I'm at the track but other than that it's 32:1 all year.