You won't have any problems with 10% ethanol blend fuel. I've run it in my Corvettes for years without a worry.

 

Avgas is leaded. Not a good idea for any car with a cat.

 

there is a station a few miles south of Floyd Va that sells alcohol free.

 

It could be a problem if your car sits. The ethanol eats through rubber hoses.

 

It's been virtually impossible to buy non ethanol in most parts of Texas for many years.

 

All modern fuel injection rubber hoses are rated for ethanol. Depending on their placement, some are rated for ethanol running through the inside of the hose, while others are rated to be fully submersible in ethanol as well.

Ethanol is cheap octane and serves as an excellent knock-quench, which most tuners realize.

 

Wrong.

 

Not necessarily. Go to pure-gas.org for a list(and locations) of ethanol free gas stations.

Only six states mandate E10 and Missouri is one of those six states, yet I can purchase both 91 and 93 octane gas that has zero ethanol in it, here in Springfield, MO(all at convenience stores/gas stations, not marinas).

In fact, I can buy ethanol free gas at 23 different stations locally, within a ten mile radius(Springfield, Republic, Nixa & Ozark, MO)

 

Texas, with all it's oil production only has 147 locations where you can by ethanol free gas, and Oklahoma, with all it's oil production, has 634 locations selling ethanol free gas, and then there is Iowa, with all it's corn production, having 245 locations selling ethanol free gas.

 

Octane is octane at the pump, whether it is 100% pure gas or gas with 10% ethanol or with 85% ethanol.

Your engine doesn't know the difference between E10 or E0, if both have the same octane, whether it's 87 octane, 93 octane or 105 octane. The exception is in the factory tune, where the tune is for 14.7 A/FM(ethanol free) or 14.1(E10) A/FM. That will make a slight in performance.

I can fill my Z06 with 93 octane E10 and then 93 octane E0 and the car will not perform any different(other than the exception noted above). The C6's are factory tuned for ethanol free gas whereas the C7's are factory tuned for E10.

But you will notice the difference between pure gas and gas with ethanol added, when you calculate your gas mileage.

 

 

You keep talking as though 14.1 and 14.7 represent a choice between two fixed numbers. In the old carburetor days, that was true. The carburetor delivered fuel volumetrically, so if it was set up for pure gas and you ran E10 instead, it would run lean on the E10, or if set up for E10, it would run rich on pure gas. In fact, that’s why ethanol got the then-correct, but now incorrect reputation for reducing emissions. An engine running lean emits less CO and unburned hydrocarbon than an engine running rich. But ever since closed loop control became standard in the early 1990’s, the function of the O2 sensors and fuel injection logic is to vary air to fuel ratio to maintain a fixed, very small, but non-zero amount of O2 in exhaust gas. So the default air to fuel ratio only matters if the closed loop system is malfunctioning and the system has fallen back into the default settings of limp home mode. Any time the system is functioning properly on closed loop, it will automatically adjust air to fuel ratio lower if there is ethanol in the gas, and then if you go back to pure gas, automatically adjust back to higher air to fuel.

With a car built after the early 1990’s (I forget the exact year), there is absolutely no performance-related reason to avoid ethanol. As I’ve said in other posts, I don’t like ethanol either, but my objections are based on its subsidized political stupidity, with Republicans supporting it to reward their farm state supporters and Democrats supporting it due to false belief that it reduces pollution. But let’s keep our objections where they belong, on the misguided politics of both parties, not on imagined performance differences. And yes, I know mileage is 3-5% lower for E10, but even there, claims are often blown up into a mythical 10 or 20% mileage drop.

 

Not a problem.

 

I would like to know more about how the computer knows the difference between pure gas and gas that has ethanol in it(not a flex fuel vehicle), with both having the same octane. Is there a special sensor that can determine if ethanol is in the gas?

I'm not speaking about driving down the interstate highway with 20% throttle application(that's not really a measurement of performance), but when I go 100% throttle application and stay in it for 15-20 seconds.

 

Your posts indicate that you know ethanol doesn’t contain as much energy as pure gas, so it doesn’t take as much air to burn a gallon of ethanol as it does to burn a gallon of pure gas. That’s why when using ethanol, the air to fuel ratio must be lower. Saying air to fuel ratio must be lower on ethanol is just another way of saying less air is needed to burn ethanol. So far, so good. Now on to your question.

The computer does not directly measure anything in the fuel itself. It does not know how much ethanol is in the fuel. What it measures is percent residual oxygen in the exhaust gas. It does that via the O2 sensors. If you’ve been running on pure gas and suddenly switch to E10, then because E10 contains less energy and needs less air to burn, then the O2 sensors sense that residual O2 in the exhaust gas is rising. It corrects for that by reducing air to fuel ratio. The actual variable it manipulates to reduce air to fuel is not cutting air. That would reduce power. It wants power to stay the same. So it increases fuel at constant air. That’s why miles per gallon drops. It’s pulsing more fuel, while flow of air and engine power stay the same. But since more fuel is being pulsed at constant air, then air to fuel ratio has dropped.

Maybe where you are getting off the track is in thinking air to fuel is the variable being directly controlled. That isn’t so. What is being controlled is percent residual oxygen in exhaust gas as measured by the O2 sensors. So if a fuel is used which has less energy per gallon (such as a fuel with ethanol or a fuel that has been blended for some reason to a lower than usual liquid density), then the closed loop system senses exhaust gas residual oxygen rising and squirts a bit more fuel at any given throttle butterfly position. When it does that, air to fuel ratio has dropped, but that’s not really the variable being controlled. It is just squirting more fuel so that it will use up all the air, and the residual oxygen in exhaust gas will stay at its very low set point.

 

I may be out of my mind, but my seat of pants tells me the LT1 is a teeny bit stronger with no ethanol 91 than the E10 Walmart 93 I've also tried in the car.

 

I’d say that’s imagination. The higher energy content per gallon of pure gas does not mean more engine power. It simply means that the engine computer will have to trim the quantity of fuel being injected a bit higher for E10 as indicated in the prior few posts. The fact that fuel gets trimmed higher with ethanol is why both gas mileage and air/fuel ratio drop a bit. Actually, your engine should be a bit stronger on 93 E10 than 91 pure gas due to the higher octane. With standard engine tune, I wouldn’t expect that to be a big enough difference to feel in the seat of your pants, but given that the owner’s manual says it’s best to use 93 in LT1’s, that implies anything less would call for a bit of power robbing spark retard as triggered by the knock sensors. So whatever small difference there is should be in the direction of the 93 E10 being stronger.

 

I would be more concerned with the 91 octane. May not hurt, but the manual calls for 93. Of course the smart as$ store clerk would have caused me to change stations anyway.

 

we have had 10% ethanol for 15 or more years in the Houston area with no problems ever since MTBE got outlawed by the Feds with all of the leaking underground fuel tanks in the 90s.

 

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If your car still has catalytic converters, you can't use avgas. It contains lead.