Gas Octane

ethanol is NOT required by the EPA. there are many gas stations around here and other parts of the country that are "ethanol-free"
edit: sans-commiefornia

that 10% is easily made up for by the rise in food costs and the fact that corn for food is having to be imported to make up for the fact that farmers are growing corn for ethanol just for the egregious federal subsidies.

 

I said, to paraphrase a little: where it's required it will be required in all grades. If reformulated fuels aren't required in your area then you're OK..but that would doubtless be true in all the other grades too.

Ethanol is increasingly being made from feed stocks other than corn...feedstocks with no food value whatsoever, grown in land not good for corn or other foods.

Even so, I'd rather pay more for my tostitos and less for terrorists to blow up troops. But that's me.

 

canada?
http://www.eia.doe.gov/pub/oil_gas/...ons/company_level_imports/current/import.html

 

octane is a rating of the gasolines resistance to dentonation by compression as compared to combustion by spark. in a stock tacoma motor you should be absolutely fine running regular. running premiumwill not increase your gas milage unless you are detonating. The only reason i could see that premium would in crease gasmilage is that some premium gasoline are not mix with e-85 ethanol which severly decreases power and gasmilage. if you can find non-ethanol blended gasoline it will probably give the best gas milage and performance.

 

Well thats cool. When I pull a tandum 12ft trailer to Colorado I will use preimum and when I go up in the mountains.

 

http://www.seco.cpa.state.tx.us/re_biomass-crops.htm

Corn is still the primary feedstock...but other sources are growing. My in-laws told me of a plant in Enid, Ok. that opened several years ago to take the wheat stalk and other agricultural by-product and produces ethanol.

I cannot believe Canada wouldn't require oxygenated fuels... certainly in congested metropolitan areas at least?

Mexico however? well..that's different...

 

I hope no one uses E85 in our Tacoma's! It's not certified for it! It could cause degrading of seals and rubbers in the fuel system, and maybe corrosion too, leading to injector clogging and very expensive repair bills.

You are right it does decrease power as ethanol has a lower energy content per unit volume. When I lived in El Paso, they would go to oxygenated blends in winter and MPG would drop 1 or 2 for the duration. But ethanol also has much higher octane than gasoline, so blending it in increases total octane of the formulation.

 

Reading some of the posts it is really surprising how many people do not understand Octane and what it is used for, I don't claim to know it all but it is my understanding that The best fuel you can put in your truck is the one with the lowest octane without getting the "ping" or "Knock", which is (or can be) pre-ignition. pre-ignition is (or can be) the result of having fuel which is too pure and to counter this a retardant must be added (Octane) it is something like adding "Water to Whiskey" it reduces the strength of the fuel. many people think the higher the Octane the better the gas (which the oil co's would like you to believe, hence the name premium) when it is really the opposite. the lower the octane the more pure Auto manuals used to explain this. Now most people think when they purchase premium they are getting the "Good Stuff" Well,, Maybe not! jmop Doc

 

That is so true...most peoples' understanding of fuels comes from the old gasoline commercials urging drivers to 'put a tiger in your tank' and fill up with "High Octane" from your Esso-Extra pump. They may never have seen the commercials, but the Madison Ave. legacy of ignorance persists here as in so many other consumer areas.

And they are all freaky about how racing fuels are 'high octane'...well they are that because compression ratios are really high and they run with timing pushed as close to the ragged edge of melt down as they can push it. They would use lower octane fuels if they possibly could.

Then there's the theory that if it cost more it's gotta be better.

The truth is it is far more complex...anyone willing to read the link I posted to the gasoline faq will learn that.

But that's only half the answer: the other half comes in just how Toyota tuned the Tacoma.

 

so you're trying to tell me that putting jet fuel into my truck won't make it fly?
http://www.youtube.com/watch?v=rJL5VC5RI20

 

I always thought the higher the Octane, the cooler the temp for combustion (lower combustion point)

I think Octane ratings are almost a moot point seeing how all vehicles (EFI) made or imported (they have to pass EPA reg.) are based on Federal EPA minimum emission standards (which also vary from state to state)

& their standards are 87 octane, nationwide....just my $.02

lead was added to gasoline as a lubricant for valve train (where valve stems go thru valve guides if I remember right)

 

I think it's safer to say...the higher the octane the cooler the temp OF combustion, although even that may not be quite right. Higher octane fuels burn more slowly and ignite less readily so you can run leaner mixtures at advanced timing with out igniting early from hot spots in the combustion chamber.

(lean mixture + advanced timing = lower emissions)

I don't think really think EPA regulations affect octane...even though closed loop engine control systems brought on by EPA (and california) demanding lower and lower emissions brought on things like anti-knock sensors.

With AK sensors you can run even a Ferrari on regular and not risk pistons falling away in chunks from pre-ignition knock! But if you want to experience all a Farrari can be, you need to run 94. So I wouldn't say it's moot either.

Even my Maxima performs better with Sunoco 93, but the cost premium isn't worth it to me. Gas mileage doesn't suffer enough to matter with 89 so I don't generally use it.

I think it was valve seats...but I see your point.

 

Fair enough, I haven't heard mention (maybe I missed it) of engine compression ratio in relation to higher octane, is there even an engine/auto manu. in the U.S. that builds a motor for production that has compression ratings higher than 8-9 to 1 ? I dunno, I'm old school & haven't kept up as such

 

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Bingo...


I had a '68 Mustang 302 with 11:1 compression. If I EVER ran regular, it pinged like a bucket of marbles, it really liked premium.

This engine has 10:1 compression and the difference between 87 and 91 is within the margin of error of most dyno's.

It's tuned to run well with regular, it's very obvious. In order to reduce pinging on my Mustang I would retard the timing way back and it would stop pinging but was noticeably slower too, even with premium. The difference with the 1GR is the ECU controls timing advance, not a distributor, and isn't adjustable.

If you COULD get a chip with a mapping that tests the knock sensors on premium it would be amazing to see what you could get out of this motor. Maybe 10 hp across the power band...the type of gain FI engines get with a chip.

 

Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. When Toyota recommends 87 (RON 91) they are telling you your engine is NOT a 'high-performance' engine.

The common misconception voiced here, that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for, is just that, a misconception.

The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.

However, burning fuel with a lower octane rating than required by the engine often reduces power output and efficiency one way or another. If the engine begins to detonate, that reduces power and efficiency for the reasons stated above. Many modern car engines feature a knock sensor – a small piezoelectric microphone which detects knock, and then sends a signal to the engine control unit to retard the ignition timing. Retarding the ignition timing reduces the tendency to detonate, but also reduces power output and fuel efficiency.

If your engine is in good tune, the recommended octane rating is sufficient and you are wasting money on the 'good stuff.' But that's fine I suppose if it makes you feel better.

I might 'feel better' if I changed my oil once a month, but . . . .

 

haha thats the sad part almost all of use small amounts of e-85 now unknowingly. the big gas companies are saving money now by blending there gasoline with up 10% ethanol. stuff is terrible for vehicles though. never new that it had a higher octane rating though. Guess ya live and ya learn which is good considering im only 22...

 

Umm...I don't think you understand...E85 is 85% ethanol...10% ethanol would be E10...they are permitted to put up to 15% (E15) which all cars are required to be capable of using, by law.

In most all metropolitan areas and many others, EPA requires oxygenated fuels..."reformulated" they call it... for emission control. The way they do that now is use around 10% ethanol, they used to use MBTE but that polluted ground water much worse (thank you CARB).

So it's not economy that drives the oil companies to do it, it's the EPA and pollution regulations. I believe ethanol is either more expensive, less available, or both. If it weren't there'd be a lot more 'flex-fuel' vehicles on the road, more stations offering E85 and an even greater push to make more of it.

 

once again i learned something i didnt now that the number after the E was the percentage of ethanol. and yeah ill go with epa to the knowledge i have of gasoline was learned in a rednecks backyard building a race chevy motor for a 1934 ford 5 window coupe

 

The octane rating not only affects the probability of dieseling, but also the speed of the flame front. Lowering the speed of the flame front means you can advance the timing slightly, which usually results in a slightly higher power output and more efficent running.

So while your engine may not ping on 87 octane, the computer may not be advancing the timing as far as it might on higher octane.

On old vehicles you adjusted the base timing, vacuum advance, and centrifugal weights or springs to get the maximum timing without pinging. Now that is done by the computer on the fly.