It costs money (and energy) to increase octane. In the refinery business, selling a fuel that has higher octane than the minimum required is called an "octane giveaway"
It is difficult to determine the actual value of ethanol in motor fuel. The large quantity used means higher octane components of gasoline are less valuable than they would be if there was no ethanol used. That means the gasoline without ethanol (usually premium grade) is cheaper than it would be if there were no ethanol used. And if there were no ethanol the price difference between regular and premium would be higher because refiners would be required to reform a lot more of the hydrocarbons into higher octane components.
I've seen estimates on what it would cost to produce all the octane necessary without ethanol that range from 5 to 50 cents a gallon.
But they did, for decades. It wasn't just Hilborn injectors at Indy. It was even some carbureted sports-car classes, back in the '50s, and even go-carts in the '60s.
The old story about methanol damaging carbs has been legend in racing for a very long time, and I suspect that someone just assumed that ethanol caused the same problems.
This was the statement: "This MIT study found that maximum thermal efficiency can be achieved with 20%-35% ethanol blends."
This is the MIT report:
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It requires careful reading. This is the "on the one hand, but on the other hand" kind of conclusions it reaches:
MIT has published dozens of articles on ethanol efficiency. The only MIT article I saw posted was intended as a reference to counter a particular false claim that was made.
retarding spark is a compromise that decreases efficiency. Fuel that burns late in the power stroke produces mostly heat out the exhaust.
Sure, but look at the first paragraph on page 58 of the report. The result is not what you might expect.
And look at the bottom graph on page 57. Surprise!
Also, look at table 9 on page 56. Five degrees of retard results in only
1.55% loss of efficiency in the highly-turbocharged engine. And 5 deg. buys you a lot of allowed boost with gasoline. As I said, the curves cross in normal driving, but the upshot is that you actually can get HIGHER efficiency (in terms of fuel volume/mi.) with the higher-caloric-content gasoline in normal driving conditions.
Overall, it's a very close call -- unless you go for a pipsqueek engine running at near hand-grenade-level peak effective pressures at nearly full throttle. Hmmm...
And the other potential efficiency gain from ethanol blends is that you can get the same power from a much lighter engine Removing a large amount of dead weight allows for lighter suspension and chassis.
It's like most engineering jobs: "On one hand, this improves results. On the other, it makes them worse..."
Running tiny engines at over 13 bar of turbo boost is not a recipe for a long and happy life. And building a tiny engine that will handle it means the engine has to be built stronger -- and heavier -- than a less-stressed engine.
And note that ethanol injection or blending is not the only way to prevent detonation in a supercharged engine of any type. For example, they didn't compare this test engine with a water-injected one.
What they were evaluating was potential fuel-volume/mile capabilities of a few engine types. It's a good report, and it shows that you don't have to give up (volume-based) efficiency when you use a lower-caloric-content fuel, like ethanol, when you can compensate with lots of turbocharging and the higher effective RON (octane) of ethanol.
But the net result is that you only get an improvement with ethanol at conditions of very high loading of the engine -- a high-speed cycle that isn't even measured in the EPA city/highway calculations, and which doesn't represent *anyone's* long-term average driving conditions.
I'd say it's about a wash. Now, let's see what they can do with a homogeneous-charge, compression-ignition (HCCI) engine
But there is no incentive for automakers to design cars that perform better on ethanol blends as long as the EPA requires fuel economy testing to done with straight gasoline without ethanol.
That 20%-30% was stated in conclusion of the study. They concluded that knock was the limiting factor in thermal efficiency (Henry Ford could have told them that 100 years ago) and that somewhere between 20% and
30% ethanol would keep a turbo boosted engine from knocking at a timing that achieved maximum brake torque under all driving conditions.
The point of citing the study was to counter the false claim that the energy content of the fuel is the solely what determines work output. The study demolishes that claim.
What you call "Normal driving" is the EPA fuel economy test driving cycles which do not push the engine very hard.
The report also showed that the break even point for fuel economy showed that for all driving cycles a small engine (1.2L) would require 16% ethanol and a large engine (2.0L) needed only 6%.
That isn't surprising. To get maximum miles per gallon you need just a little less timing and a little less ethanol than the point where maximum thermal efficiency occurs.
BTW the compression ratio and boost used in this study are not particularly high. I've seen studies using higher compression and boost where ethanol performed even better.
None of this has much real world significance.
In the real world ethanol doesn't increase octane and therefore doesn't raise the knock limit. In the real world ethanol allows the oil refiners to cut costs and put a much lower grade fuel in the pipeline.
If you find regular grade gas without ethanol it has the same octane as regular with ethanol. It will cost more because it costs more to produce. If the entire fuel supply had to be bumped up by the 3-4 octane points that ethanol provides, the cost increase would be even greater.
Around here it's the same grade of gas that gets ethanol or not. The same gas, out of the same tanks, into the same tanker trucks - some gets ethanol added, some does not. Depends what brand station is getting it. Or so I've been told by local fuel distributors.
Huh? They're spectral opposites. No Libertarian I know has ever, or would ever, stand for totalitarianism, nor for the tenets which support Fascism. (OK, mebbe a bit of nationalism, as patriotism, but that's it.)
Don't know about in the USA, but in Canada the ethanol is generally not added at the refinery, and the same refinery effluent is sold with and without ethanol - and generally speaking, engines run better without the added hooch.
Think again. MANY fuel engines run carbs. Great big "toilet bowl" or "sewer pipe" carbs.
And running high octane non ethanol fuel has the same (or better) results on a boosted engine, using less fuel
Methanol corroded the metal of the carbs - as well as bearings, camshafts, crankshafts, and cyl heads. Common practice was to flush EVERYTHING after a run - including changing the oil, to preserve the "hard parts". Ethanol, on the other hand, has a low corrosiveness to metal but is very hard on many "soft parts" like gaskets and seals due to it's solvency. Corrosion with ethanol is mostly due to the hygroscopic nature of ethanol, and phase separation which allows the saturated ethanol to drop out of suspension, so the water trapped in it can cause corrosion.
Back in the day (when gasoline was gasoline) they used to market some stuff called "Dry Gas" that you dumped in your gas tank to keep the water from freezing in the fuel system. Dry-Gas was nothing but alcohol.
Did water actually freeze in fuel systems? Yup, it was fairly common up north where your car might spend the night in a garage that was 10 degrees, or more, below zero.
If you can cram in enough air, or supply enough oxygen by other means (NOX or NitroMethane comes to mind) you can cram enough low callory fuel into the engine to make insane horsepower, if the engine only needs to run for 6 seconds or so.. On a fuel dragster you could cut the ignition at half track and see very little power loss as the engine is running almost totally on detonation.. The limit to how much power they can produce is almost totally the amount of fuel and liquid oxidizer they can cram into the cyl without hydrolocking the cyls.. An average top fuel dragster engine turns only 712 revs over the quarter mile!!!! (and burns over 20 gallons of 90% nitro/10% methanol in 3 seconds. That's 4620 cu inches of fuel. On an 8 cyl engine that is 2848 power strokes - over 1.6 cu inches of liquid fuel per cyl per power stroke. On a 640 cu inch engine, or 80 cu inches per cyl, with a compression ratio of 6:1 the compression volume of the cyl is 11 cubic inches. With 45.5 psi of boost and the space taken by the liquid fuel, the compression ratio equivalent is roughly 28:1.
If you are building for only 3000 or so revs of engine life you can do LOTS of stupid (and expensive) things to make power!!!
In the US there are two grades of rack gas at the terminal. They are 84 octane and 91 octane. If the tanker truck is filled with E10 then ethanol is blended with 84 octane as the truck is filled. If the truck is filled with regular gas without ethanol a blend of about 50-50 84 octane and 91 octane are put in the truck. Premium gas without ethanol is 100% of 91 octane blend stock. Premium with ethanol is a blend of 84, 91 and ethanol. They are blended so that regular is 87 octane and premium is 91. The oil distributors try not to ever give away octane for free.
Most gas stations have blender pumps so the motorist has a choice of 87, 89 or 91 octane. The 89 octane is half regular and half premium.
I live in the Pacific Northwest. I have been told by more than one person who works with small engines that we get crappy gas here. The evidence they use is the damage done to the fuel systems of small engines. The folks who have told me about this problem are from the greater Seattle area and the greater Portland, OR, area. And the same people have told me that using or ethanol free gas prevents the fuel system problems. But this is just anecdotal evidence. My own personal experience is that since changing to ethanol free gas a little over a year ago I have not had any problems with the fuel systems on my small engine powered machines. Using the regular gas with ethanol I was forced to take apart and clean the carbs 4 or more times in the span of 6 months or so. So whether it is because of bad gas fortified with aclohol, or extra water in the gas because it absorbs more when alcohol is added, or something else that clogs the fuel passages in the carbs when I use gas with ethanol added I don't care because when I use ethanol free gas I don't have to take apart and clean the carbs on my small engines. The extra 25 cents per gallon I pay is well worth it in time and aggravation saved. And one of my small engines, I think it is the Stihl chainsaw, requires gas with lower octane rating. I guess premium fuel burns too slow. Eric
Yup, In Thailand that is a "long tail motor" and normally used by fishermen who use open boats. The most commonly used in the larger boats - maybe 10 M., fishing boats is a single cylinder diesel engine
- hand crank starter :-)
They even make kits to convert common small motors and on the river, in Bangkok, a mate clamed he saw a small-block Chevy engine on one :-)
When gasoline is shipped, it's stored in tanks that hold 2-4 million gallons. (But the industry uses barrels [42 gal].)
The gasoline is left to sit for days, and then the operator goes to the valve on the lowest part of the tank floor, and drains off the water. Sometimes there is an inch, sometimes far more. (On a 120 ft dia tank, every inch is about 7,000 gallons.) At later stages of delivery/storage, again water is drained off.
The methonal must be injected at the tank loading point, because otherwise it would absorbing water as fast as it could. I've not been in the pipeline business for decades, but when I was, that was the SOP.
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