93 octane in California (?)

MuffinMcFluffin

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For those who are unaware, due to ethanol restrictions in the state, no regular consumer pump sells 93 octane fuel, though we do have E85 pumps here and there.

So I had done my research in the past about where to get racing fuel, and I finally started asking about it at a place in my area. The woman said that it's really supposed to be for off-road use here, but that if I choose to do with it what I will then that's on me. I had to fill out forms and stuff declaring that, and next time I do a fill-up I'll consider doing a blend with 91 to achieve 93.

The different unleaded octane ratings offered that I heard were 95, 98, 100, and 110. I didn't get any particular brand names or anything, but my guess is with it being race fuel and all that it is all top-tier gasoline.

Now comes an interesting concept, which is if I choose to ever purchase them as canisters. A five-gallon canister costs the following amounts for each rating (which I will recognize is significantly more expensive than others that can buy 93 in other states, but bear with me for now):

95 - $59.50
98 - $57.45
100 - $55.70
110 - $54.75

So the first question I asked myself is: "Why are higher ratings cheaper?" Then it occurred to me that if I'm trying to achieve a certain rating in a blend (such as 93), then I would need less of their gasoline to fill up, so I would be paying more on my end to fill up the rest with 91.

I'm doing the math with you guys live here with a piece of paper, pencil, and calculator, so hear me out and tell me if my numbers make sense here. Our tank can hold 12.4 gallons, so every time I fill up the tank, each rating would equate to using the following amounts of that specific gasoline:

95 - 6.2 gal
98 - 3.543 gal
100 - 2.756 gal
110 - 1.305 gal

Let's assume that 91 octane rated gas in my area is $3.50, which is about what it is here in the Sacramento area. What I'm going to do is calculate how much money I'd spend on 91 when blending against each octane rating, then I will proportionately grow/shrink that amount to the equivalent how much I'd spend for a single tank of gas.

95
$21.70 (6.2 gallons of 91) + $73.78 (6.2 gallons of 95)
= $95.48 per tank of gas

98
$31.00 (8.857 gallons of 91) + $40.71 (3.543 gallons of 98)
= $71.71 per tank of gas

100
$33.76 (9.644 gallons of 91) + $30.70 (2.756 gallons of 100)
= $64.46 per tank of gas

110
$38.83 (11.095 gallons of 91) + $14.29 (1.305 gallons of 110)
= $53.12 per tank of gas

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Okay, so the math even more so seems to favor the 110 octane fuel, which I can also get at their pump if I get approved. However, I do not know if it costs the same rate at the pump (meaning $54.75 per 5 gallons, or $10.95 per gallon).

Ignoring the fact that this is going to be considerably more expensive than just using 91, is there something that I'm missing here that suggests I should be blending more of 95 instead of less of 110 to achieve the same rating? Is the disparity between octanes an important facet that I should consider? Does the 110 have a lot more ethanol content that I should be concerned about? Is it potentially not as quality of gasoline, and should I look deeper into the brand/product they use for each one?

What other other people in California doing, and how much are they spending? I know that when I lived in the Bay Area, there was a gas station in the Woodside area that sold 100 octane at the pump for $7.60, which would be costing me $54.71 per tank, so even though it's cheaper than the 100 here, the 110 here still edges that out. Without us having 93 at all anywhere, I'm guessing this is simply the best I can possibly get.

Thanks for those who have read and/or for those who can provide some supportive input.
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Does anyone know if there's lead in racing fuel?
Think lead will ruin the catalytic converter.
 
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MuffinMcFluffin

MuffinMcFluffin

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Does anyone know if there's lead in racing fuel?
Think lead will ruin the catalytic converter.
They sell both leaded and unleaded. These were unleaded prices.

I'm not saying that means it doesn't contain lead, but I'm saying they make that distinguishing remark in their product names.
 

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If your car isn't tuned for 93 or higher, just blend 2 gal (and no more) of E85 and 91 to achieve 92. And E85 is a lot cheaper too at around $2.40/gal in Calif. When the car is nearly empty, find a station that has both E85 and 91, add 2 gal of E85, and then the rest with 91. You'll be at around E22 and 92 octane.

http://www.wallaceracing.com/ethanol-mix-calc.php
 


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I still don't understand why their 110-rated variety is cheapest. If pump gas costs go in order of 87<89<91 then why would the racing fuel costs be ordered 95>98>100>110? There are undoubtedly more differences than just the octane ratings in these fuels.
 

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You need to find the ethanol content % for each of the fuels. 100% ethanol is around 113octane, so that 110 May be close to e100.
 
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MuffinMcFluffin

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If your car isn't tuned for 93 or higher, just blend 2 gal (and no more) of E85 and 91 to achieve 92. And E85 is a lot cheaper too at around $2.40/gal in Calif. When the car is nearly empty, find a station that has both E85 and 91, add 2 gal of E85, and then the rest with 91. You'll be at around E22 and 92 octane.

http://www.wallaceracing.com/ethanol-mix-calc.php
I have a TSP Stage 1 tune.

I've done this twice before. I'm actually convinced that the first time I did it, I accidentally filled it up with Diesel #2 instead. I remember a lot of visible exhaust at the time and chalking it up to it being colder weather, but the more I think about it, the more I may have just had a brain fart and taken the green pump (because E = eco-friendly, hellooooo everybody!!!) instead of the yellow pump by accident. I hope I didn't screw anything up by doing that the first time around.

But also perhaps this didn't happen too, because I haven't faced any ill effects and I think I would have warned myself plenty by doing it. Maybe my car was just popping its E85 cherry or something.

Anyway, I think I've only gone as far as like 1-1.5 gallons or so. Without a flex fuel kit, I didn't want to go too far with it. It sounds like these cars have had trouble on the TSP Stage 2 tune with that much ethanol anyway, so it definitely scared me into doing it too often regardless.


I still don't understand why their 110-rated variety is cheapest. If pump gas costs go in order of 87<89<91 then why would the racing fuel costs be ordered 95>98>100>110? There are undoubtedly more differences than just the octane ratings in these fuels.
You and I both. That's why I did the math as I was typing this post, to look more curiously into the subject matter.


You need to find the ethanol content % for each of the fuels. 100% ethanol is around 113octane, so that 110 May be close to e100.
I'm going to do this next. thanks for the heads up!

But I don't know if 1.3 gallons of E100 would be any worse than the suggested two gallons of E85, would it?
 

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I have a TSP Stage 1 tune.

I've done this twice before. I'm actually convinced that the first time I did it, I accidentally filled it up with Diesel #2 instead. I remember a lot of visible exhaust at the time and chalking it up to it being colder weather, but the more I think about it, the more I may have just had a brain fart and taken the green pump (because E = eco-friendly, hellooooo everybody!!!) instead of the yellow pump by accident. I hope I didn't screw anything up by doing that the first time around.

But also perhaps this didn't happen too, because I haven't faced any ill effects and I think I would have warned myself plenty by doing it. Maybe my car was just popping its E85 cherry or something.

Anyway, I think I've only gone as far as like 1-1.5 gallons or so. Without a flex fuel kit, I didn't want to go too far with it. It sounds like these cars have had trouble on the TSP Stage 2 tune with that much ethanol anyway, so it definitely scared me into doing it too often regardless.




You and I both. That's why I did the math as I was typing this post, to look more curiously into the subject matter.




I'm going to do this next. thanks for the heads up!

But I don't know if 1.3 gallons of E100 would be any worse than the suggested two gallons of E85, would it?
I have an independent E85 station right next to a Chevron. Since we get 92 premium here, I calculate a mix as close to the owners manual stated max of E15. I end up getting 0.5-1 gallons of E85 and filling up with premium.

I can't vouch for the long term safety of using above E15 without a flex fuel kit and tune, but I'm sure if you're within a few percent of E15 it's probably fine.

Even if you don't quite get 93, you're still boosting the octane by some amount and getting a benefit.
 
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MuffinMcFluffin

MuffinMcFluffin

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Do the states that have 93 at the pump deliver E15 ethanol?

Even if the 95 that I mentioned was E15, there’s no way in hell I’m spending $90 per fill. I’d rather risk putting in more ethanol or leaving things as is, heh.
 


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So I know this has been asked a lot and there are always people that say mixing a little e85 to 91 is bad and then there are others that say its perfectly fine. What are everyone's thoughts on that? I got the Phearable tune and on Chevron 91 my knock control was at .81 (It is california summer on stock intercooler) but I added around a gallon of e85 and my knock control stays at .49-.55
 
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MuffinMcFluffin

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So I know this has been asked a lot and there are always people that say mixing a little e85 to 91 is bad and then there are others that say its perfectly fine. What are everyone's thoughts on that? I got the Phearable tune and on Chevron 91 my knock control was at .81 (It is california summer on stock intercooler) but I added around a gallon of e85 and my knock control stays at .49-.55
I will go ahead and say that I've read people stating the ECU readout is a little wonky at first when you reflash your vehicle. Not sure if it's this tune in particular or what, but that driving it around a little (maybe about 30 miles?) and then eventually restarting your car at one point can normalize it.

Perhaps it's coincidence, or perhaps the ethanol maybe even helped it normalize. Regardless, I don't think your knock control was ever actually at .81.

That being said, I'm not too privy on it yet since I don't yet have a way to monitor mine, but I don't know if it's necessarily good if it's sitting at .55. I know you put a range, but I think it should really be at .49-.51. Anyone know for sure on that one?
 

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So I know this has been asked a lot and there are always people that say mixing a little e85 to 91 is bad and then there are others that say its perfectly fine. What are everyone's thoughts on that? I got the Phearable tune and on Chevron 91 my knock control was at .81 (It is california summer on stock intercooler) but I added around a gallon of e85 and my knock control stays at .49-.55
Honda says the car is safe up to 15% ethanol. I'd go as far as to say mixing a little ethanol into the E10 you get at the gas station to make it ~E15 is 100% safe and has no chance of causing issues. **

If you mix more and end up with E20 or something higher, all bets are off.

**From a Manufacturer's statement/warranty perspective.
 
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MuffinMcFluffin

MuffinMcFluffin

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Honda says the car is safe up to 15% ethanol. I'd go as far as to say mixing a little ethanol into the E10 you get at the gas station to make it ~E15 is 100% safe and has no chance of causing issues. **

If you mix more and end up with E20 or something higher, all bets are off.

**From a Manufacturer's statement/warranty perspective.
Do you guys get 93 up in Oregon? If so, is it rated at E15 as well?

And is calculating ethanol content equivalent to calculating octane? Just kind of by computing "weighted averages" by using their numbers? (like half E85 and half E15 = E50?)
 

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Do you guys get 93 up in Oregon? If so, is it rated at E15 as well?

And is calculating ethanol content equivalent to calculating octane? Just kind of by computing "weighted averages" by using their numbers? (like half E85 and half E15 = E50?)
Yes, it's just weighted average.

No, we only get 92 octane E10. I end up mixing in a very small amount of E85 to make it around E15. I'm not going to sweat if if I end up anywhere between 12-18% ethanol, but I'm not going to deliberately target E20 or something higher.

I'll say that even with just mixing up from 92 E10 to E15, I see a lot less knock control creep.
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