Quote :

"The Environmental Protection Agency's Office of Transportation and Air Quality is starting to think that raising the octane level that's considered to be regular gas could go a long way toward making modern, downsized engines even more efficient. 95-octane gas could be possible, but the investigation into the issue is still getting underway. It could be many years before any changes actually happen, if they ever come at all. Christopher Grundler, the office's director, discussed the idea to Automotive News. With a higher octane rating, fuel becomes less likely to pre-ignite and can withstand higher compression ratios. Such a change would theoretically allow small displacement engines to eke out even more horsepower, assuming they are engineered to take advantage of the higher-octane gasoline. According to Grundler, any changes to standard octane levels would first require significant research. The government would need to know that the higher cost of better fuel is actually a worthwhile investment, Automotive News reports. In much of the US, regular gasoline is currently 87 octane, although it varies by region. Many modern, turbocharged engines already need at least 93 octane. For example, putting in premium allows the Ford Mustang with the 2.3-liter EcoBoost four-cylinder to produce its stated 310 horsepower and 320 pound-feet of torque. The pony car can also run on regular in a pinch but peak power drops off."

Holy crap, is the EPA actually thinking about doing something that makes sense? I'd like to think that at the same time they'll remove ethanol requirements, but that's really asking way, way too much from them.

http://www.autoblog.com/2015/08/07/95-octane-cars-more-efficient-report/

8/7/2015 4:33:57 PM

yeah, wouldn't getting the corn out of our fuel do more for efficiency?

8/7/2015 5:48:15 PM

so...I'd like to see a study on keeping it the same octane levels, but removing ethanol from gasoline, and selling purer ethanol (maybe E85 or something) more widespread, so that manufacturers could design cars to use ethanol (E85) injection under heavy demand when the octane boost/intake charge cooling is needed.

[Edited on August 7, 2015 at 8:21 PM. Reason : ]

8/7/2015 8:20:52 PM

^^sure would

8/10/2015 8:40:07 AM

That's not really efficiency...

Higher octane means higher compression means better efficiency in the higher percentage of energy in being utilized to move the car forward.

E10 is more efficient then the straight 93 was due to the 10% ethanol cooling cylinder temps. But your MPG is worse since ethanol has less energy per gallon than gas... E10 is just putting less energy in per gallon.

MPG isn't really efficiency.

8/10/2015 9:33:51 AM

They will probably do it by dumping ethanol in it...

8/10/2015 11:32:05 AM

^^ you're narrowly defining "efficiency" as basically BTUs per mile. Different metrics are useful for different things, but I can't think of anything that metric would be useful for.

8/10/2015 8:16:00 PM

? <--- that was the n thing that's the symbol for thermodynamic efficiency.

I didn't define it. It's the definition of efficiency.

Just because 4 cubic feet of coal yields more energy than 4 cubic feet of gasoline doesn't mean a mechanical cycle would be more efficient with it.

I know you are a smart dude but I guess you are forgetting efficiency is energy input over energy output. Changing the energy input does not make getting more out more efficient.

It's apples to potatos.

[Edited on August 10, 2015 at 8:49 PM. Reason : .]

8/10/2015 8:46:53 PM

I'm agreeing with Duke, if I can extract more power out of the same volume of fuel then to me that sounds like better efficiency to me.

8/10/2015 9:45:14 PM

^^ raising compression ratio is raising thermodynamic efficiency, everything else being equal.

8/10/2015 10:12:38 PM

yes. which is what i said the first time.

removing ethanol is just getting 33% more power out of 10% of your gas which would yeild ~3% better mileage without really changing the efficiency of anything.

otherwise everything should be like #6 fuel oil.

[Edited on August 11, 2015 at 7:39 AM. Reason : .]

8/11/2015 7:37:59 AM

On a related note, during the news this morning they said that gasoline prices could drop as much as 70 cents a gallon over the next few months as the refineries stop producing the more expensive summer blends.

I'd be pretty damn happy about that

8/11/2015 9:03:37 AM

It's already 2.18 here if we go below 2 I'll be stoked

8/11/2015 10:54:20 AM

Yeah 2.17 out on S. Saunders.

Quote :

"It's already 2.18 here if we go below 2 for premium I'll be stoked"

8/11/2015 12:20:45 PM

yeah i'm on capital on the other side.

8/11/2015 2:15:09 PM

$2.97 for premium today in CLT. They are one of two stations in a center, and jack their prices up. Usually I time my fill ups better, but didn't get gas last night and had to get it this morning.
I usually pay about $2.50 for premium.

8/11/2015 7:22:03 PM

how are they supposed to magically almost double mileage by 2020 to meet cafe standards?

I wonder if the force calculations even make sense ?

8/12/2015 7:59:25 AM

i read a couple of years ago about E30 and left with the distinct impression that it (somehow) gives you better fuel economy despite the higher ethanol content...it also costs less and has reduced emissions

whatever happened with that? or am i even thinking of the right thing?

8/12/2015 3:13:48 PM

I think you might be thinking of something else. Because you can't magically remove energy from a gallon of liquid and somehow go further on it.

8/13/2015 12:41:05 PM

yeah... i think he's saying something like.

E30 allowed the compression to raise high enough to gain the 9% in fuel energy lost back in increased Otto Cycle Efficiency. (doubtful but possible?)

8/13/2015 12:42:43 PM

efficiency (eta) doesn't matter. MPG doesn't really matter.

all that matters is miles per dollar

8/13/2015 8:49:59 PM

^^^ & ^^

yeah, it's a combination of E30 and an engine designed to use it: http://www.nytimes.com/2013/05/05/automobiles/squeezing-more-from-ethanol.html

8/18/2015 9:49:31 AM

Quote :

"efficiency (eta) doesn't matter. MPG doesn't really matter. all that matters is miles per dollar"

word. in the practical sense of the word, efficiency refers to dollar efficiency, not the efficiency of extracting energy out of fuel. there's some overlap, but there's too much nuance for the average joe.

The average joe wants to put as little money in to go as many miles as possible.

8/18/2015 10:29:44 AM

Agreed. It doesn't matter if the combustion cycle of an ethanol tuned engine is able to extract more power, percentage-wise, from the specific volume of ethanol. You're starting with less energy to begin with, so you're never gonna beat 100% gasoline, even if the gas-only engine can't match the high volumetric efficiency of the higher octane ethanol fuel.

From the article:

Quote :

"Using high-octane premium-grade gas in an engine that does not require it offers no benefit. But in engines designed to squeeze the fuel-air mixture to very high pressures before igniting it with the spark plug, high-octane fuel burns predictably and can produce more horsepower. (On the other hand, burning low-octane gas in an engine tuned for premium grade can cause erratic combustion, or knocking, and result in severe engine damage.) Ethanol contains only about two-thirds as much energy as gasoline, gallon for gallon. But if it is burned in engines designed for high cylinder pressures, it will produce competitive horsepower."

I don't think anybody in this thread is arguing that an engine designed specifically for high octane ethanol blend fuel will make less horsepower than an engine designed for high octane pure gasoline. The point is that fuel economy won't be better. At all. The bottom line is there is less energy in those chemical bonds. If E30 gasoline only costs 2/3rds the price of 100% gasoline then you'd probably start to see some support (heck, even 3/4ths cost will prob gain support). But that will never happen.

[Edited on August 18, 2015 at 1:02 PM. Reason : k]

8/18/2015 1:00:18 PM

I use 85.

8/20/2015 2:26:20 PM

Quote :

" If E30 gasoline only costs 2/3rds the price of 100% gasoline then you'd probably start to see some support (heck, even 3/4ths cost will prob gain support)."

never underestimate the power of the corn lobby

^i thought you were a liberal hippy; ethanol is bad from an environmental standpoint, food policy standpoint, and global emerging markets standpoint. Use regular gas.

[Edited on August 20, 2015 at 2:59 PM. Reason : .]

8/20/2015 2:57:48 PM

Haha what gave you that impression. I hate hippies.

I'm confused now. Does 85 Octane gas have Ethanol in it?

8/20/2015 3:36:25 PM

i read that as E85 and not 85 octane because 85 octane is shitty

8/20/2015 4:02:28 PM

Why's it shitty? It's the regular gas in Denver. No reason to put anything higher unless I'm driving at sea level.

--Most of my driving is above 10k feet.

[Edited on August 20, 2015 at 4:08 PM. Reason : s]

8/20/2015 4:07:55 PM

It's shitty b/c it's low octane. However, it works out there because of the high altitude. Would never fly on the east coast.

8/21/2015 8:29:04 AM

yeah you have no oxygen in your air so not having any octane in your fuel is no big deal.

8/21/2015 8:57:14 AM

Yeah I read somewhere that for non-turbo charged engines there's a 3-4% loss of horsepower per 1,000 feet of elevation. Crazy.

8/21/2015 9:08:59 AM

85 probably isn't high enough octane at elevation though if you need premium

8/21/2015 12:46:35 PM

Yeah it's not but I don't need premium.

--Like here premium is only 91. There's no 93.

[Edited on August 21, 2015 at 1:23 PM. Reason : s]

8/21/2015 1:22:56 PM

But hey, at least with the lower octane your fuel costs less, right?






























lol yeah right

8/21/2015 3:07:35 PM

I get 30 mpg and fill up my tank once a month. Maybe 2 times if I go on longer weekend trips. Almost never drive during the week. Gas prices aren't a huge concern of mine. They need to actually go way up as we Americans don't consider the entire price of gasoline in the consumer price at the pump.

8/21/2015 3:21:15 PM

Must be nice. I'm making up for you; I fill my tank every 2-3 days.

8/21/2015 9:16:24 PM

Quote :

"They need to actually go way up as we Americans don't consider the entire price of gasoline in the consumer price at the pump. "

GTFO with that kind of talk.

8/24/2015 8:53:06 AM

Was hoping I'd catch someone with that one.

8/24/2015 8:56:03 AM

Stopped for gas off 40 otw back from the beach yesterday, thankfully was not driving the 335

87 - $2.25
89 - $2.94
93 - $3.24

6/21/2016 12:00:28 PM

wow. a full $1/gal more for 93?!

I miss the days of 10 cent deltas...

With that said, $2.08 regular off 401/70

6/21/2016 1:32:02 PM

da faq?

$2.64/gal for 93 Shell V-Power on South Saunders.

6/21/2016 2:58:37 PM

1.94 in NE Alabama.

6/21/2016 3:09:08 PM

that is how prices are here (SW VA) at stations which have ethanol-free 93 octane gas.

6/21/2016 3:45:54 PM

$2.33 at Costco for 93

6/21/2016 6:17:25 PM

Quote :

"In a recent independent study, AAA found that gasolines with fewer detergents left 19 times more deposits on engine intake valves than top-tier fuels after 4,000 miles of driving."

http://www.autoblog.com/2016/07/07/aaa-claims-not-all-gasoline-top-tier-study/

7/11/2016 9:45:43 AM