E10 (ethanol/ gas) and 2-cycle engines

Triple.

Cheaper, considering the overall production costs. After considering

1) the 1.05:1 cost of production and 2) the immediate 15% loss in efficiency of the E10 vs standard fuel, I can't see how anyone in their right mind thinks it's an eco fuel. Someone suckered our gov't into subsidizing it and that should be stopped immediately, even retroactively. Feh! My Scout preferred it over the bottom-octane fuel in the '90s, but that's the only time I've felt a difference.

Now the poor illegals here in the USA are paying more for their tortillas, too. Wah! ;)

Reply to
Larry Jaques
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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.

======================================================= [Ed]

This is why I said you have to read the study carefully. You've drawn two incorrect conclusions here. First, you're assuming that maximum fuel economy, in terms of gallons used per mile, occurs when thermal efficiency is maximum. That could be true if you were using a single type of fuel, but, as the study says, it's not true for a gasoline/ethanol blend:

"Different degrees of spark retard were applied to reduce the amount of ethanol required. Spark retard up to 5 CAD increases miles per gallon of the vehicle. This is because efficiency loss is insignificant with 5 CAD retard, but ethanol fraction decreases significantly therefore increasing the energy content of the fuel per volume. This suggests that the spark retard and ethanol injection can be incorporated together to optimize the efficiency of the engine." [p. 59]

The other assumption implied by your statement is that the conditions described -- 9.2 CR, and one bar (14.5 psi) maximum boost -- are conditions at which maximum efficiency is achieved. Far from it. In fact, running at

14.5 psi of boost, you're either accelerating hard or you're going like hell.

There are several problems with this, among them that there's no attempt to show that a 9.2:1 compression ratio is the correct one for optimum efficiency (fuel economy, on a miles-per-gallon basis) of any possible combination of gasoline and ethanol. Another is that maximum efficiency isn't going to occur at full-throttle conditions. If you read the study carefully, you'll see this:

"Engine in vehicle simulation was used to estimate the amount of ethanol required to operate the engine without knock in various driving cycles. 2.0 L engine within 1 bar maximum boost required about 7.4% of ethanol fraction in volume for US06 driving cycle. Less than 1% of ethanol was required for city and highway driving cycles. US06 represents more aggressive driving style with high acceleration, so the engine operates and knock limited region more often, which results in a high ethanol fraction.

"As the engine size was reduced from 2.0 L to 1.2 L, the fraction of ethanol required increased about twice for US06 cycle." [p. 59]

In other words, the actual fraction of ethanol required by the 1.2 L engine for knock-free performance is around 1% for city driving, and (if you check the charts) around 3% for highway driving. The "US06" cycle, a "supplemental" cycle, is about hard acceleration and high speeds. It's not about efficiency, and it doesn't represent typical lifetime driving cycles.

As I said earlier, it's close to a wash, unless you spend most of your time going like hell with a tiny engine.

BTW, one bar (14.5 psi boost, or two atmospheres absolute) of turbo boost is pretty rough on the engine, if you drive that way most of the time. The Cosworth 2.4 L, 700+ hp engines I used to inspect at CART races ran at 9.3 psi of boost. A street engine can take two or three bar for short cycles, but that isn't where fuel efficiency lies. The 2.0 L GM engine used as a baseline turbo engine in the MIT study is limited absolutely to two bar of boost.

==============================================================

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.

============================================================== [Ed]

I don't know who made that claim, but you're right, it certainly isn't true.

==============================================================

What you call "Normal driving" is the EPA fuel economy test driving cycles which do not push the engine very hard.

============================================================= [Ed]

They aren't trying to push the engine hard. They're trying to achieve something like a real-world, typical driving cycle. And they're pretty good at achieving that.

If your full-throttle percentage of operation is typical and realistic, you get a better AVERAGE miles-per-gallon efficiency by retarding spark timing for those short periods of the overall cycle -- which requires less methanol, which, in turn, improves your (average) mileage.

============================================================

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%.

============================================================ [Ed]

Where are you reading that? The 16% ethanol only shows up for the most extreme cycle. See my quotes from the report, above.

===========================================================

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.

============================================================= [Ed]

Yes! And the amounts of ethanol required actually are quite low, for normal driving cycles.

=============================================================

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.

============================================================= {Ed}

Yeah? For how long, before it coughs up a rod?

Of course ethanol will allow higher compression and/or higher boost, but again, the more ethanol you have in the mix, the lower its per-volume caloric content. "On the one hand...on the other hand..."

=============================================================

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.

Reply to
Ed Huntress

The startup checklist for the multifuel truck I drove in the Army included draining the water separators. When I learned to preflight a Cessna the instructor carried a fuel sampler tube like this to check for water in gas drained from the wing tank.

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jsw

Reply to
Jim Wilkins

I didn't draw incorrect conclusions. Those are not my conclusions.

The point of citing the study was to show that increased thermal efficiency that are possible with ethanol blends can offset losses due to lower heat content.

The 20%-35% blend is required to achieve maximum thermal efficiency at all load conditions (including WOT for passing at 80 mph)

Engineers have known for many decades that higher compression will increase efficiency. The SI engine can be just as efficient as a diesel if the compression and effective pressure are as high. The problem has always been the fuel will not tolerate it. As a result the real world gasoline engine is about 40% less efficient than the diesel.

The4 US06 cycle is the one that most closely matches the actual mileage motorists get.

The fuel economy tests are the ones that don't match the mileage real drivers get.

In other words, you didn't read what I wrote but instead you are going to tell me what I wrote.

EPA FET generally are much better mileage than the match average driver gets.

But more important, if that type of driving was all the driver ever needed engines would be designed a lot smaller.

The fact is the current strategy is to build a much larger engine that gets poor mileage all the time so that the driver has some power to spare when needed. . What the study implies is that a different strategy of building a smaller engine that gets good mileage when "normal driving" but also can deliver high power for things high speed passing on a mountain road.

The supplemtal test procedures were developed because of complaints that the standard procedures overstated the real world mileage people get.

The cops will stop you before that happens unless maybe you are pulling a big boat.

Ethanol in higher concentrations would allow the freedom to design a smaller engine that can accelerate like a big engine but not get bad mileage in what you euphemistically call "normal driving". Look at the gains in mileage between a 1.2L and 2.0L. With say 25% ethanol it is possible to have a 1.2L that has the same power as a 2.0L running on straight gasoline but gets significantly better mileage in all driving cycles. Sure the 1.2L could get a little better mileage under low loads with say 5% ethanol but then you wouldn't be able to make full use of the compression and boost which would mean the motorist would think the engine is a dog when passing on the highway.

In Brazil they design cars that do mush better on E25 than on straight gasoline. They also allow the motorist to choose how much ethanol goes into the tank along with the gasoline.

In the US the EPA doesn't allow and doesn't allow mileage testing with ethanol. The EPA doesn't allow it because they are working for the auto makers and the oil cos. They know that allowing higher blends and testing fuel economy with those blends would lead to smaller engines that get the same power and consume a lot less fuel.

But it will happen someday just as Henry Ford predicted. The industry efforts to thwart market realities will eventually fail.

Reply to
jim

Wow! I'd never seen the exact stats on that. Impressively insane!

--snip--

Grrr!

Reply to
Larry Jaques

I saw something like this in a 007 film once. What a hoot!

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Reply to
Larry Jaques

Oh, then she'd know, huh?

I suggest adding "Liberal SF nutzoid tattooist" to the quote, then. Just so people don't get the wrong idea about you.

ROTFLMAO!

Trolls hate that. And that's one of the reasons I still try to get you guys not to answer his/her trolls. Stryped is a perfect example. As is FrontalLobotomy Machinist.

OMFG! Did she miss a single buzzword? I dislike her already, just from attempting to digest that. Ick!

Reply to
Larry Jaques

In the US the EPA doesn't allow higher concentrations of ethanol and doesn't allow fuel economy testing with ethanol.

Reply to
jim

Supporting data???

The primary one "blenders' credit" ended at year end 2012 so it's going on two years now. And, despite the common misconception, it didn't go to the ethanol producers nor the corn/milo producer but to (ready now?) the oil companies...

Do comparative incentives/tax breaks and the like between big oil and other segments of the US economy and oil is way up there on the rankings...

...

Reply to
dpb

But that IS where the maximum power is extracted from the fuel. The highest HP per lb of fuel burned - which translates to the highest efficiency. On a spark ignition engine that is at the point where maximum torque is produced, and with the engine totally unthrottled - ie- wide open throttle loaded to maintain maximum torque RPM.

works even better with direct injection.

Actually in many situations it IS.

Sounds like EcoBoost.

Reply to
clare

A large part of the knock reduction potential of ethanol results from the evaporative cooling of the intake charge due to rthanol evaporation. The same cooling helps horsepower by increasing the density of the air charge, raising the volumetric efficiency, and therefore the effective compression ratio. Depending on the design, the two can cancel each other out, so there is NO improvement in knock resistance - but a little more power from a lot more fuel.

Reply to
clare

Gunner Asch on Fri, 30 May 2014 23:56:19 -0700 typed in rec.crafts.metalworking the following:

Hmm, sounds interesting - a CNC controlled tattooing bot.

Oh dear - one more skilled trade being outsourced to machines.

R2D2?

-- pyotr filipivich The fears of one class of men are not the measure of the rights of another.

-- George Bancroft

Reply to
pyotr filipivich

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"...elaborate torture and execution device that carves the sentence of the condemned prisoner on his skin..."

-Kafka

Reply to
Jim Wilkins

That is true but its not very relevant to fuel economy for the cars on the road.

Hardly any WOT operation occurs and WOT on a street car is not very wide open.

Reply to
jim

C3PO. The bot has to regale you with liberal banter during the screwing, bluing, and tattooing, right?

Reply to
Larry Jaques

WOT is WOT, streat car or race. WOT means non throttled intake. If I floor the accellerator on my 3.8 Taurus or my 4.0 Ranger, the throttle is "wide open" If I am loaded and geared such that the speed does not change at that throttle position, and the engine is "on the cam" I am getting as much horsepower out of every lb of gas going though the engine as I can possible get with that fuel, timing setting, and compression ratio (and exhaust system, mixture, valve timing, and a host of other settings)

Now, if you can adjust an engine so you have only the displacement, compression ratio, timing, and mixture required to produce the amount of power required to move the car at the speed you want to go at all times, you will get the best fuel economy with that engine running "wide open throttle" at all times. That's what a deisel does, other than being able to control the displacement - and a turbo diesel gets real close to that as well because it can control the amount of air consumed by the engine without throttling losses. That is where a large part of a diesel's economy comes from.

Reply to
clare

On a typical street car running WOT at a constant speed, it will get you down the road at 100mph (or faster). Due to extra friction and wind resistence at that high speed you will get a lot poorer fuel economy than you would running at partial throttle at 40 mph.

Then you won't have enough power to accelerate in order to reach that speed or when the road starts to go up hill you won't make it.

Maybe if the engine is small and is charging a battery that drives the vehicle. But then you have huge efficiency losses in carrying around many pounds of battery wherever you go.

Less energy consumed in pumping losses is not the only reason diesel is more efficient. Even if you are comparing a gasoline engine at WOT and a diesel putting out the same power, the diesel still converts more energy to work because of the higher compression and because it develops more internal pressure when it is most effective (i.e. near the top of the power stroke)

Reply to
jim

If the engine is sized for maximum output running the car at 60mph, it won't. But I know what you mean. I DID state if the engine was "loaded and geared such that the speed does not change at that throttle position"

- which might mean you are headed up a 30% grade with a 19 foot boat behind your fire breathing 6.2 liter monster!!

Untill the displacement, compression ratio, valve timing, or fuel delivery is adjusted to provide the extra power - which. to some extent, is what supercharging/turbocharging, displacement on demand, and variable valve timing, are all about - and what GDI and stratified combustion technology help with (and again, where diesels come into play)

Now I woulsd not necessarily sat "best fuel economy" - but "best efficiency."

Correct. But note - I included a lot of other conditions in the equation - including CR and VE - and stated (IIRC) it is LARGELY the reason it is more efficient - or something to that effect. Definitely diesel has other advantages (as well as drawbacks) to it's design.

Today's computer controlled turbocharged direct injection, variable valve timing and displacement on demand engines are getting a lot closer to diesel efficiency territory.

Reply to
clare

Who knew you were spreading that conspiracy k00kery in here as well!

Reply to
Rolling Block

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All gasoline vehicles can use E10. Currently only light-duty vehicles with a model year 2001 or greater can use E15. Only "flex-fuel" vehicles can use gasoline with an ethanol content greater than E15.

The energy content of ethanol is about 33% less than "pure" gasoline, although this varies depending on the amount of denaturant that is added to the ethanol. Thus, vehicle fuel economy may decrease by up to 3.3% when using E10.

Reply to
Rolling Block

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