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Discussion Starter #1
So it seems like every gas station around here has a single pump hose for the 85, 87, and 91 octane fuels. Some of these pumps, like the Costco I've been filling up at, have some crazy long hoses... Probably 15' or so to where it connects to the top of the pump, and then another 6' or so to ground level. I did some checking and it seems that most pumps have a "fuel bowl" within them that's used to store fuel that is pumped from the storage tanks. The storage tank is typically 1.5 to 2 gallons, and is filled with the fuel that the last guy used.

So, just volumetrically, 21' of 3/4" line holds .48 gallons of fuel. Add in another 1.5 gallons (minimum) of crap 85-octane fuel from the person ahead of me, and that's almost 2 gallons of the 85 garbage every time I try to fill up with 91. Most of the time my fill-ups are around 9.5 gallons, which gives me an overall average of 89.7 octane when I'm paying for 9.5 gallons of 91.

No wonder Brian was so surprised at the amount of power it was making (on the low side).

I need to find a station around here with pump hoses for each octane and then see if the tune files that I couldn't use work better.
 

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Or keep a fuel can that you can use to capture the remaining lower octane. Many years ago I was forced to do that very thing. The newer single output hose pumps had been installed and the highest octane was reduced to 91. For the power levels I was operating at it could become potentially catastrophic.

So whenever I fueled so did my yard equipment so to speak LOL
 

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Ill be interested to see the proof in the pudding.
 

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Who would use 85 octane ? I don't know why we have low octane fuels since higher compression is more efficient.In Japan high octane is 96 or higher and 98-100 octane common .
At least in GA. I can get 93.I have been using STP octane booster every other tank.$4 at wallmart.
 

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Discussion Starter #8
Who would use 85 octane ? I don't know why we have low octane fuels since higher compression is more efficient.In Japan high octane is 96 or higher and 98-100 octane common .
At least in GA. I can get 93.I have been using STP octane booster every other tank.$4 at wallmart.
At 5400', anybody without a forced induction car usually does, and unfortunately, even a lot of the ignorant public uses it on their FI vehicles since the computer can adjust for it. The lack of air at this altitude helps with detonation, so they can get away with it. O2 % in air at this altitude is only about 17%, whereas at sea level it's around 21%. Doesn't sound like much, but that's a 20% reduction.

As far as "proof is in the puddling", I did some tests a few weeks ago by throwing a couple gallons of E85 in the tank and never saw any negative corrections. Once I started filling up again at Costco using the mile-long hose pumps, though... was right back to getting negatives. I'm going to see if I can find any stations with separate hoses for the different octanes. Even if it costs more, and it likely will since Costco gas is freaking cheap compared to everybody else, I'll at least try a couple tanks and see if there's any difference performance-wise.
 

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Who would use 85 octane ? I don't know why we have low octane fuels since higher compression is more efficient.In Japan high octane is 96 or higher and 98-100 octane common .
At least in GA. I can get 93.I have been using STP octane booster every other tank.$4 at wallmart.
I've been asking myself this the last 10 years. Additives aside, Why are we using post-lead 1970s fuel grades? Our engines have come leaps and bounds since then and they require a change in the gas we get from the pump.
 

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I've been asking myself this the last 10 years. Additives aside, Why are we using post-lead 1970s fuel grades? Our engines have come leaps and bounds since then and they require a change in the gas we get from the pump.
I'm all for some good old tetra-ethyl lead, but apparently the EPA is not. But, I'm sure with all of our technology there are alternatives to make fuel better, or, get you some al-key-haul...
 

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I'm all for some good old tetra-ethyl lead, but apparently the EPA is not. But, I'm sure with all of our technology there are alternatives to make fuel better, or, get you some al-key-haul...
Ethanol isn't the answer either. At 50% the BTU (e100 versus straight pure gasoline) it's an inefficient fuel when were talking straight energy efficiency and mass-use.
 
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Ethanol isn't the answer either. At 50% the BTU (e100 versus straight pure gasoline) it's an inefficient fuel when were talking straight energy efficiency and mass-use.
I'm not looking at it from an efficiency point of view, just performance, as you mentioned the advancement in engines over the past 50 years, the biggest of which to me is the resurgence of power. Unfortunately the powers that be are not really concerned with facilitating this advancement.
 
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I'm not looking at it from an efficiency point of view, just performance, as you mentioned the advancement in engines over the past 50 years, the biggest of which to me is the resurgence of power. Unfortunately the powers that be are not really concerned with facilitating this advancement.
Very true. I was just thinking realistically since despite most people now owning these high-strung, small displacement engines, we still have to think of the fuel supply chain for what it is- "feeding the masses". That supply chain just needs to cater to these new engines.
 
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Its weird how 87 is more volatile and you make less power on it then 93 a fuel that is less volatile but burns hotter and combustion is more easily controlled n make more power on. But the 87 burns faster which leads to knock. Thats that wierd balance between the two, you kinda want the volatility of the 87 if ever was possible but the control and heat of the burn like 93...obviously this is where corn comes in?
 
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how often and how much e85 can one add to a fill up of 93 on the stock tune?
 

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Discussion Starter #16
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I was told to not add more than a couple gallons to the tank.
To make up for a small reduction in octane I would only add 1/2 to 1 gallon per tank.
 

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Discussion Starter #19
Yep, OAR has been at -1.00 as long as the temps stay below 90 or so, so I've been thankful for the cooler temps finally getting here. Once the temps started climbing in August/Sept, though, if I have any higher-gear loading at all (even a mild incline), it'd start pulling timing and drop the OAR to -.96 or so. On a couple of the more aggressive tunes, it went from -1.00 to -.91 when the ambient temp was around 100 degrees as soon as I got into 3rd gear on a small incline. I saw negatives of -3.69, -2.82, -2.20, and -2.00 for cylinders 1-4, respectively, on revision 4 when the temp hit 100. That's when I let him know the fuel I had was apparently just garbage... and given what I've finally come the realization of, it makes sense that the tune was too aggressive for the octane I was trying to give it. When he's expecting decent 91 fuel to tune for and it's more like 89, then the tune is going to suffer for it.
 
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