Higher octane gas

Yes, all else being equal, a higher compression engine requiring higher octane should be more efficient than the one made for the lower octane.

I don't see how switching from AKI to RON for the octane rating would lead to car manufacturers making, and people buying, high octane fueled cars. If people are willing to sit in line for regular gas that is a penny cheaper a gallon, I think they would do the same if the listed octane was 93 instead of 87. The minimum octane for regular needs to be increased.

 

Yep if we regulate the wrong thing simply raising octane will do nothing for the fleet mileage standards.
Key here is the government (EPA/CARB) are again behind the times regulating the wrong things (CAFE, oxygenate, MON)

which means you need a smarter government would switch to RON, as no one builds carburetors anymore. Then revise oxygenate to what actually is needed for fuel injection engines (much less). Finally if they fixed the epa testing so it better reflected the real world (better on highway worse in city) instead of 1940s LA, and replaced the cafe with the new test, and regulated that, car makers would probably design more effiecient ices for the real world and demand higher octane to meet mileage standards.

 

Do you really not see that presenting this the way you did is grossly misleading.
And the way the article is written too ????

The point of the article IS that a higher compression engine design is more efficient.
But it is written in this warped way that makes it appear that octane alone will do the trick. It won't.

It seems that the engineers have been able to make higher compression, more efficient Atkinson engines run without needing higher octane.

THE OCTANE RATING IN AND OF ITSELF has no bearing on efficiency. It is the design of the engine that is the key.

 

They are saying cars could be re-designed for higher MPG at higher octane.
AKI (R+M/2) may be outdated spec but just reporting Research Octane (RON = R) instead of AKI is a minor point for the most part. Not sure if going to RON only spec helps or hurts ethanol (need to know ethanol RON and MON). Maybe that's a hidden agenda.

The question I would have, many of us get lower MPG due to reformulated gasoline and ethanol mandates, and we pay more. But that requirement goes back to 1990 studies. Now modern cars like Prius make nil emissons, presumably even on non-reformulated gasoline. So I'd like to know if reformulated gasoline still makes any sense. Basically we have Congress/EPA controlling gaso recipes, so its hard for anyone to do much change without a massive overhaul in the overall system.

EDIT: Wikipedia says ethanol is approx. 90 MON and 109 RON, so that's a pretty big spread, so going to RON only would directionally help ethanol look a little better, I am thinking.

 

This is why people have a hard time believing "studies."

The good news is that you're only wasting money if you put higher octane gas into a car that does not require (or even recommend) this "premium" fuel. You will not hurt the car or decrease herd immunity for preventable diseases, or knock a hole in the ozone layer.
You'll just be wasting money.
You'll also increase the profit margins for your friendly neighborhood gas franchise.

So?
Knock yourself out.

Make it E0 "premium" while you're at it!

 

Atkinson engines trade power for efficiency. Without hybridization or wide range variable valves, they need to be larger than an equivalent Otto in order to meet American desires in a car.

Direct injection can give the efficiency and power, but with increased particle emissions. Europe may require them to have an exhaust filter in the near future.

The above engine designs could use an even greater compression ratio and longer power stroke when made to run a higher octane. The higher compression ratio, the greater potential the engine has at extracting more energy from the gasoline. The Atkinson cycle doesn't truly have a higher compression ratio; the fuel charge is only subjected to the pressures found in a port injection Otto designed for low octane. Higher octane means the compression stroke can be increased, which allows the power stroke to also be increased.

The OP article is clunky. Heres the original article, but the full version is behind a credential(pay) wall. An Error Occurred Setting Your User Cookie

 

It will still have a bearing. Some HCCI designs still make use of spark ignition under loads in which compression ignition wouldn't be optimal or simply not work.

Mainly it is because knock can happen during the power stroke. The piston isn't the only source compressing the air fuel mixture. The flame front of the controlled detonation can build enough pressure in the air fuel mixture between it and the descending piston head to cause uncontrolled detonations if the octane is too low.

 

Theoretically a HCCI ICE is not really much more efficient than a turbo charged di ice with vvt and variable lift so that it can go into the miller cycle. Most of these engines are tuned for power instead of efficiency, but we now have the excellent hyundai 1.6L in the sonata eco actually following these principles. Add cooled egr and even better. A HCCI ICE needs all this hardware plus better electronics so it will cost as much if not more. Its advantage is a little bit more efficiency, less NOx, less particulate maybe no spark plugs, but current levels of particulate are fairly low (more comes from other sources in most communities) and NOx is taken care of in the catalytic converter. Drawbacks are much larger ice needed for the same power.

I wouldn't expect high hcci penetration for at least a decade if ever. Its main benefits will be in city mpg, but add a hybrid system, and that may beat hcci, so manufacturers need cost to be much lower than making a hybrid.

But higher octane can both allow higher compression and smaller size for the same power for such an di turbo engine, which could both lower cost and add efficiency (or add power for the same price).

Here is a strange hyundai varient from hcci that may be less expensive to produce.
Hyundai Developing Gasoline-Burning Compression-Ignition Engine – News – Car and Driver | Car and Driver Blog

 

You guys have completely lost me, speaking a foreign language.

 

Study said if we changed our regulatory environment, made higher RON rated gasoline, automakers could build more efficient ices for the gas. The combination would reduce oil use and save money (engines plus oil upgrading cost less than the saved oil, and creates jobs). It would be a win win.

But there is a tech in the lab HCCI which works much like a diesel ice, but would have lowered priced pollution control equipment than a diesel. This would not benefit from the upgraded gasoline. IMHO HCCI is a tech longshot to improve fuel economy. That means if our regulators worked right the country should have an open fuel standard with higher RON rated (higher octane could simply use more methanol or ethanol to cheaply get the octane) then car manufacturers would respond with engines for this to meet cafe standards, unfortunately EPA/CARB/Congress is unlikely to implement simple regulations that make sense, they like complicate thousand page regulations that don't work well. EPA instead spent a lot of time trying to push E15 out to gas stations, which would do nothing positive for the country. CARB is focused on getting hydrogen vehicles on the road, and figuring out how to raise taxes to do it.

 

One thing tripping me up is the unrelenting barrage of acronyms. I know they become second nature, when you're into something. But they're addictive, and can confuse/baffle/alienate listeners on the peripheral.

Just for an exercise, try saying something completely free of acronyms. I think it's actually beneficial, makes you shift gears.

 

LOL, I can guess where the funding for that one came from.

 

But that is a flawed argument. It has the cart before the horse.
If the market demanded more high octane fuel, it could be produced in the blink of an eye.
The LACK of enough high octane fuel is NOT the problem.

 

Demand can also be created by marketing. How else do you explain the demand for Beats Electronics?

 

RON and MON and aki, are used for octane rating. No one knows what they mean but google. OK googled - Research Octane Number, Motor Octane Number.

HCCI -> stands for homogeneous charge compression ignition which to me is more confusing than the acronym. Its a gasoline engine that in a certain mode ignights gasoline from compressing the air like a diesel instead of using a spark plug. The engines haven't made production yet and those in running cars also have spark plugs or glow plugs to get things started, or to provide more power. To get the pressure up a lot of cooled exhaust is used, it requires a turbo or a super charger, or in some cases both are used, direct injection is required with current technology.

Hyundai is working with a simpler model that isn't HCCI because it uses a stratified charge after top dead center instead of homogenous charge before. That means the gasoline is not in the engine early enough to cause detonation. Hyundai then can eliminate the spark or glow plugs. They do need to heat the air on cold days to get the engine to work, so their is additional hardware there, and a little less efficiency than HCCI because of delayed timing, but it is a simpler problem to solve.

 

It's considered polite to spell out the acronyms the first time you use them.

 

Sure but RON, MON, and HCCI are like RADAR and SCUBA, where the acronym is better known than the words that make it up.

It doesn't sound right to type radio detection and ranging (radar). I think these others are the same, but yes HCCI is a future technology that probably requires links.

 

Yeah but he'd be mired. Austingreen, thanks for the patient explanations.

One thing I suspect, sometimes we go out of our way to pile on the adjectives, JUST to justify creation of an acronym. ICE for example: engine used to be ok. I think it's still just fine. It's pretty much cargo cult to repeatedly qualify it as Internal Cumbustion Engine.

Anyway, thanks again, interesting info

You know, the last time I bought a shop manual (Honda) I found I was pretty much asea: the escalating use of acronyms made certain sections unintelligible to me. ;(

Merged, and by the way, I was a SONAR operator, you're right: I have no idea what it stands for, now. Maybe not at the time either. It's a word in its own right.