Pure Gas ( No Ethanol ) experiment

The other downside is that you now have a bunch of gasoline contaminated water to deal with.

My understanding is that premium gas has a lower energy content than regular. Any fuel economy improvements seen in using it is from the engine burning it more efficiently.

 

Yeah that's the deal breaker.

And it's maddening, to be reverse-engineering an additive out of the mix.

I keep wondering that: if the higher octane's trait is to resist ignition better.

 

NOT universally true. Or at least not significant.
It depends on how they achieve the higher octane rating.

It is possible to "refine" out the high volatility components from "regular" and make the octane higher......but that is expensive.
It is easier and cheaper to add something like lead or alcohol to boost the octane and those additives might lower the energy content.
Tetraethyl lead did not to any significant degree. Ethanol does.

 

Well now you can stop wondering.

Higher octane is designed to resist ignition at times when you do NOT want it......like due to the heat of compression or of a glowing carbon deposit.
It does NOT resist ignition from the spark but it might burn a tiny bit slower.

 

Octane rating - Wikipedia
Phrase that pays: "Octane ratings are not indicators of the energy content of fuels..."

Fortunately, the efforts of the Farm Lobby and the Petroleum Lobby have resulted in people trying to actually measure things out in the real world with, like, a real 30.48cm ruler.

Gasoline gallon equivalent - Wikipedia

 

IIRC, octane measures a fuels ability withstand pressure before detonating. Our "muscle cars" and high performance (high compression) motors of yesteryear required higher octane so as to prevent pre-ignition. I was running out of fuel in a high performance boat (455 ci high-compression Olds) years ago and the nearest dockside station only had regular or diesel fuel available. We added a few gallons of regular and the boat almost refused to start, barely had enough power to get on plane, and darned near would not stop (kept rough idling, can't pop the clutch to kill it like with a car).

Regarding ethanol, my understanding is that it adds cost, robs efficiency, and is essentially a government mechanism to subsidize corn-belt farmers.

From fueleconomy.gov:

Ethanol contains about one-third less energy than gasoline. So, vehicles will typically go 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on 100% gasoline.3

Rather than belabor my own perceptions about ethanol being a corn-belt handout, I humbly recommend googling "ethanol subsidy" before you pillory me.

 

It is a measure of the gasoline's ability to resist ignition from compression.

High compression engines have a high expansion ratio that means more energy can be harnessed from the burning fuel. All else being equal, the high compression engine will be more thermally efficient than a low compression one.

 

Chevron's top octane up here (94) is ethanol free...

 

I was also hearing this from an engineering relative working at a refinery, long ago. But it also depended on the blending specifics for particular batches, so one couldn't make a blanket statement about it always being true. At that time (before the ethanol mandates, and under different EPA fuel property requirements than today), lower octanes usually had slightly better energy contents than did the higher octanes.

 

From my experience if I use Chevron or shell gas regular unleaded. It seems to be better than Fred Meyer’s or Arco gas. The engine seems more quiet. I have over 74k miles now. I think the regular unleaded 87 Chevron and Shell gas is equal to Arcos and Fred Meyer’s premium grade gas.

 

I try to buy my gas at Costco. It's ethanol blend where I live, but it's Top Tier and their price is always competitive. Plus, 4% rebate with their charge card.

Drives my wife crazy when I look for Costco's along the way on a trip. I get the gas and the $1.50 dog/soda and back on the road. Apparently that isn't suitable road food, or so I've been told.

 

I don't recall the numbers but at one time I looked up the EPA MPG for IIRC a Chevy Impala running on E10 and E85. That E85 better be REAL CHEAP given the MPG loss. And you'll be stopping at (adulterated) gas stations a lot more often.

You are going to get a LOT of exercise! And have no time to read PriusChat

I run only E0 in my string trimmer, chain saws and riding mower. Around here it is 91 octane like it or not.

Some years ago I tried unscientific testing using regular versus high test gasoline (WELL before the government mandated ethanol contamination of gasoline) to see if I got better MPG. I don't recall how much it may have been but I do recall the price per gallon difference was not justified.

 

Sure.

It is just another one of those vast Government conspiracies, designed to make the rich farmers even richer.

Truth: Most farmers are FAR from rich.
Clean air regs require an "oxygenate" in the gas and ethanol is the best we have now.

So I guess those places in South and Central America where they burn E85 to E100 are doing that just to make their farmers rich too.

Most of the exaggerations about ethanol have their roots in the petroleum industry......where they don't like losing 10-15% of their oil market.

 

Good point. The original mandate was for oxygenated fuel, which would improve emissions on older vehicles without the new closed loop control systems. MBTE was the chemical of choice, but that was found to cause other environmental problems. Ethanol is available and was substituted as the oxygenating agent.

The requirement for oxygenated fuel has its origins in CARB and the EPA, not in the agricultural industry.

 

(Sigh)... Okay then I stand corrected, Corporate farmers are not rich and air quality is helped by diesel tractors cultivating corn-based ethanol which itself provides greater mpg efficiency.

 

Jay Leno's take on ethanol, how much he loves it & what it has done for his personal vehicles.

0 to about 1 minute 30 is good...then it goes infomercial in my opinion.

www.youtube.com/watch?v=DL_8SkZjEPc


Rob43

 

It does not. It is domestically sourced, but per volume the energy density is less than gasoline. And, many of the tractors in the midwest (the corn belt) run on bio-diesel.

 

In general Premium might have more energy due to more aromatics (toulene etc)..
However, in the USA, the EPA regs for reformulated gasoline basically put a max on aromatics. So in RFG area (my area) I am expecting almost equal energy content between grades. In non RFG (conventional gaso) areas, I expect there could be more aromatics...but not guaranteed. The refinery has recipe options, so it depends what they want to use. I am thinking bigger companies do not have as much freedom (EPA has regs on conventional gaso too) as smaller cos. So if there was a 93 Octane E0 at some off-brand or outside of USA, I might take a guess it could be good MPG stuff. Of course these parameters are not posted on the pump, so testing eg MPG or density would be needed to determine. I sometimes measure how many grams in my gas can after getting 1.000 gallons to get density, but there's no fun in my area, it's all mandatd RFG E10.

 

If you actually do a little bit of fairly easy research......instead of just passing along biases and Internet myths............
You would find that there really aren't many "corporate farmers" and where they are, they mostly grow products to be processed by the same corporation. Think Green Giant green beans, just for instance.

 

Last I heard, there were more problems with bio-diesel that there are with ethanol.....in their respective engines.
I don't know how much of it is currently used but 5 years ago or so it wasn't well accepted.