If you had your choice to use 91 octane non-ethanol gas or 93 octane valvetech ethanol gas (lots of additives apparently to break up ethanol) what would you use?

Thanks

91
My 2001 Chevy Dually with the 496 went from 10mpg towing down to 7mpg with the stupid ethanol and other crap they add to the gas! How is it environmentally friendly to burn more fuel!!!!

It depends on what octane your engine needs. As long as your engine is fine with 91 then I would run that.

I'm surprised at that. I had a 496 in 2001 2500hd and ran E-10 95% of the time. I got about 11mpg in town and 13mpg hwy. Towing 8-10k was always 7-8mpg. I never saw a diffference running non ethanol fuel.

Poll should be straight gasoline or alcohol contaminated gasoline.

It was over this winter and I believe the gas was the oxygenated winter blend as well. Whatever the case, when I bought my 38 Donzi in '07 and towed it up to NJ from Fla., I got just under 10mpg. In Feb. '10, I got barely 7!!!!!!
My truck has the re-chipped computer with cold air intake and free-flow exhaust and that is why I used to see 10 towing no problem.

been running 90 octane no ethanol in my boat with no problems, seems happier than with 93 pump gas but hard to say

You should expect lower MPG with (90% gas/10% ethanol) than with 'pure' gasoline, and here is why:

Gasoline is a saturated hydrocarbon, with a fixed amount of energy, in each gallon.

91 octane gasoline has an energy density of 44.8MJ/kg

energy density = amount of energy stored (available) in a given volume or given mass
MJ = megajoule
kg = kilogram

So 1 gallon of 91 octane, 'pure' gasoline is 125,000BTU


Ethanol is an octane booster, and does not contain the same amount of energy as gasoline.

Ethanol, which is rated at 129 octane, contains 84,600 BTUs per gallon.

So to get 91 octane blends of 90% gas, and 10% ethanol, they can and do use lower octane gas in the blend.

10% Ethanol + 90% lower octane gasoline, resulting an 91 octane rating blend, if you do the math, contains around 112,000BTUs per gallon.

Bottom line, to do the work of 1 gallon of 'real' gas, you need to burn 1.12 gallons of gas/ethanol blend.

In other words, 12% more gas/ethanol blend to go as far.

I bet you the 'tree huggers' didn't share this info with you. Not as "green" as advertised!

Guess I should fatten up my jetting about 10 % ?

Always go with straight gas if possible, but in the midwest it is vertualy not a option, the green people have drank the "coolaid" many years ago. they first started with mtbe and it took a long time to find out that it poluted the water system ( it does not evaporate). Etheanol is there current panacea, as filler we use more fuel per mile. (it is also rough on seals, fiberglass and rubber products) it is bad for marine applications, but we have worked around it here. the not so funny part is that they now charge more for less now!