During the early pandemic, I almost never drove, so I didn’t cycle my fuel for a month or more. I’m told that’s long enough to make ethanol fuel absorb water and harm engines, so I switched to ethanol-free.
My questions are -
Is it possible that my car was engineered for ethanol mixes, and I’m actually creating problems by switching to pure gas?
Does ethanol content even matter in large engines? Am I overoptimizing for no good reason?
For what it’s worth, it seems to be running fine, and it feels like I get a little more power out of it. It’s a 2007 Honda Odyssey.
In general, this is not likely, unless the car is really, really old. And if the car is really, really old then it’s not at all likely to have ever been engineered for ethanol. The problem is usually in the other direction. If you have a car that wasn’t engineered for ethanol mixes or higher ethanol content, then certain components (especially certain rubber and plastic bits) can erode from the higher ethanol content and fail. Newer cars to older fuels as you are doing is almost never an issue.
In your specific case, a 2007 Odyssey will definitely handle both E15 and pure gasoline with no issues. I don’t know if your Odyssey can handle E85 as it was somewhere around 2007 or 2008 that many vehicles started making that switch.
If you aren’t driving, blended fuels do degrade faster so there is actually a good reason to do what you are doing. Keeping the gas tank full also helps as that helps to prevent oxygen in the air from degrading components in the fuel.
You do. Ethanol has about a third less power per gallon than pure gasoline. I don’t feel like plugging through the math right now but IIRC pure gasoline is going to have about 5 percent more energy content than E15. Not a huge difference, but “a little” more.
All automobiles solid in the United States (which I’m assuming is where you are) have been approved for the use of up to E15 (15% ethanol blend with gasoline) since 2001. US Department of Energy Alternative Fuels Data Center: E15. All vehicles that can use E15 can also use pure gasoline without modification, and in fact E15 will give about 5% lower fuel efficiency as compared to pure gasoline, albeit with lower particulate emissions (although higher emissions of other potentially hazardous substances which makes the pollution tradeoffs somewhat questionable). Actual perceived power output depends on the compression ratio of the engine and its torque curve but I suspect most cars will have better better performance with pure gasoline even though ethanol (or methanol) will provide a higher effective Research Octane Number (RON) and better thermodynamic performance in an optimized engine.
Ethanol is somewhat more hygroscopic (water absorbent) than gasoline and also is more prone to evaporation over time, but the same is true of the more volatile substances in gasoline, so storing gasoline for long durations or not operating a gasoline engine for an extended period of time will result in residues (colloquially: varnish) that can clog fuel injectors or carburetor jets as well as increasing the amount of water in the fuel mixture which results in poorer combustion. Any petrofuel engine should be operated for at least a few minutes once every few weeks just to cycle fuel, and if you intend on not operating an engine for an extended period of time it is advised to add a fuel stabilizer and run it through the engine to protect against corrosion and residues, or else drain the engine of fluids entirely (not necessary unless you are storing for several years at a time).
With the collapse of the Joint Comprehensive Plan of Action (e.g. “Iran Nuclear Deal”), the rise of North Korea as a credible nuclear threat, and the general instability of nuclear-capable Russian Federation, feeling “uncertain” is rational and probably even an understatement, notwithstanding the Peoples Republic of China attempt at power grabs in the South China Sea. I would not endeavor a quantitative estimate of the likelihood of a nuclear conflict in the foreseeable future but it does seem to be trending upward and to no one’s advantage. Anyway, don’t let your gasoline engine sit for months at a time without running it for a few minutes so that you’ll be well prepared for the post-apocalyptic world of George Miller which comes in the form of “600 horse of fuel-injected vengeance”.
Those with larger motorhomes often use no-ethanol fuel in the generators to prevent fuel breakdown and varnishing as fuel sits in the system during the off-season.
Treat my above comments as applying specifically to gasoline-mix engines. Diesel (and kerosene), by nature of its less volatile composition and longer hydrocarbon chains, tends to be more stable, although it is still advisable to run a diesel engine at least every few months just to make sure that lubricants (and the contaminants that may be in therm) don’t separate and bind up the moving assemblies within the engine.
Not to mention the oil film on any engine will eventually thin and admit of corrosion. Any multi-cylinder engine will always have at least one cylinder open to ambient.
When I first read your post I had no idea that such engines existed. But I immediately thought “Yanno, that’s mostly true, but only if the firing is roughly even. I wonder if anyone ever decided not to do that, for shits and giggles if nothing else?” Took some searching to find, but lo and behold, they do exist and even have a cute name.
There are a few other possible exceptions, like engines with a reduced intake cycle, or that shut off cylinders completely, though I’m not certain there are any actual examples that fit.
I admit that article confused me a bit about the parallel twins. My Dad had a Norton 850 when I was a teen. The two cylinders fired alternately. So both pistons were going up and down in sync, but on opposite strokes of the 4-stroke cycle; e.g. one’s power stroke is the other’s intake stroke and vice versa. It’s not clear to me that there’d necessarily be any point in the full 720 degree cycle with all valves closed.
It now occurs to me that any otherwise conventional 4-stroke engine with electrically controlled or actuated valves will could have all cylinders sealed when shut down. The “one cylinder always open” effect is an artifact of mechanical camshaft timing which leaves the engine in a “suspended animation” state wherever the crankshaft happened to stop after the last run.
My Chevy Silverado make more horsepower and torque with E85 over regular gasoline, 380 to 355. I comes at a price though, I get about 5 fewer miles per gallon.