I hate cars

I don't think you understood what I said. I named the reasons why you lose power and mpg on 87 and energy content was not one of them. I'll summarize one more time:

Detonation by itself causes a loss in mpg and power

Pre ignition by itself will cause a loss in power and mpg.

The timing retard that's a result of the ECU trying to protect the engine from detonation will really hurt mpg and power.

This has nothing to do with energy content and premium does not burn any differently than regular.

Acura-OC

Read my first post

".....Sounds good in theory but In the real world, it barely affects performance, or fuel economy."

And if it doesn't burn any different than regular where does it lose energy? Engine is not running much hotter.

NorCoTL

So it doesn't seem that you have any real world experience in verifying your theory if you have not tried it or tracked it. Please do it try it and report back... I have not bothered to try it on the TL but I have tried it on several other vehicles and have tracked differences in MPG based different fuel ratings.

The gasoline does not lose energy, the engine burns it less efficiently. It is a process called ignition timing. When the timing is not optimal then efficiency is reduced. If the engine is less efficient in the way that it burns the fuel then loss of power and increase in mpg result. It is actually a very well known and integral process of internal combustion engines.

The engine would not run any hotter as the energy of the fuel is not being combusted properly/fully. This also means that more unburned fuel exits the combustion chamber, since it is unburned, no extra heat just extra hydrocarbons out the tailpipe.

nfnsquared

I do. I've run 48 almost full tank loads of 87 (15+ gallons of 87 mixed with <2 gallons of 91) and there was no difference on the MID MPG display for highway driving (~450 miles on the tank) between this tank and the previous tank of 91 (also ~450 miles). Again, this is all highway driving with the occasional slow down/stops for small towns on a state highway. Since the MID only displays whole numbers for MPG, there could be a fractional variance in MPG. I have never done a manual calculation, but I'll try to remember to do so next time I make the trip.

And what's up with Nebraska and 87?? WTF?

NorCoTL

In my previous trackings I have found the smallest differences between 87 and 91, but there were differences. Often fractional yes and often barely enough to justify the cost of the higher fuel. The differences often come down to a gallon or less of difference over the course of the tank. Doesn't mean there isn't a difference though, it is just a small difference. Also doesn't mean that there may not be a long term effect, even a marginal one like slightly dirtier combustion chambers. Driving habits will most likely have a larger impact than dropping a rating level in fuels.

I have not experienced that issue in Nebraska myself but it is mostly likely they are serving their regular clientele and your not it (even if you go through their on a weekly basis)... Out of curiosity what route are you taking? Most of my Nebraska trips stay fairly close to I-80 but when I have ventured into the smaller towns and away from the main thoroughfares I do remember a lack of premium fuels. Not just in Nebraska though, I remember seeing that in Kansas, Missouri, Oklahoma, and quite a few other states. as well. Although it was almost always at small stations that didn't see many out of state license plates.

Acura-OC

You are right I do not have real experience with TL but I did use 87 in my prior car Lexus LS400 without any noticeable differences.

Now I am just wandering if I will notice any loss in performance and MPG with TL. I still have 3/4 of a tank of 91 it will be another week or two before I will need to fill up.

You said that portion of the gas will be unburned which will result in loss of power that could make sense but ECU consistently adjusts mixture (air to gas ratio) to make sure optimal performance. Wouldn't ECU just lower the gas portion to make sure it will fully burn which also will result in loss of power?

NorCoTL

There are four cycles to the internal combustion engines we are discussing here. Also known as a "four stroke" engines. Intake, compression, combustion and exhaust, in that order... The ECU adjusts the air/fuel ratio as part of the intake stroke/cycle. The determining factors here are more demand (throttle) based as well as altitude/air density based (dirty air filter can affect this as well), the cold start cycle also runs in this category. The fuel performance, octane related is not necessarily accounted for here. It is more accounted for in the combustion cycle/stroke when detonation/knock would be sensed (this can cross over into the compression stroke/cycle as well if the detonation/knock is a pre-ignition issue).

Note that the above is an extremely simplified explanation. The knock/detonation/pre-ignition explanation has been covered elsewhere on this site much more effectively by others. But if you hook your tailpipe up to a exhaust sniffer while you are running through a tank of lower octane fuel, a rise in HC's (hydrocarbons) is often quite evident. That rise in hydrocarbons is an indicator in loss of efficiency.

Keep in mind the differences could very well be minor, but they are there. The ECU can accommodate to an extent but there are always compromises that are made when operating outside of the recommended fuel types. Those compromises have consequences, even if they are miniscule.

nfnsquared

OK, sounds like at least 3 of us are in agreement that the loss in MPG (if any) is fractional, at least for highway driving (91 vs 87). This is certainly not an endorsement to go against the manufacturers recommendation of 91, just a statement of fact based on real world experience.

I hate cars

I explained it twice now. Forget energy, you're focusing on energy and completely missing what I'm saying. The burn rates and energy are nearly identical between 87 and 91.

Ignition timing leads the piston to TDC. The air fuel is ignited before TDC based on combustion chamber design, load, and piston speed along with many other factors such as compression ratio, temperature, and octane to name a few. The point of leading the piston and igniting the mixture while the piston is still coming up in the bore is to attempt to get the majority of the cylinder pressure created by combustion at 14 degrees after top dead center. This might mean leading the piston by 20 degrees before top dead center. When the pressure peak occurs before or after 14 degrees, power and mpg is lost.

When there is detonation caused by low octane you usually get the peak too soon and instead of a controlled burn you get an explosion which is the pinging sound you hear. This in itself costs power. The energy content of the fuel is irrelevant.

When you experience preignition you not only ignite the air fuel mixture too soon and try to force the piston back down the wrong way which costs power, you also lose most of your power stroke because the pressure peak occurred at the wrong time so you're not contributing to power, you're losing power.

If it's not bad enough that you lose power from detonation and preignition by themselves, the ECU also steps in and retards timing to protect the engine from damage. This means the plugs are firing later and your in cylinder pressure peak is occurring too late. You lose both power and mpg from late ignition timing. Again, energy content plays no role here. You're igniting the mixture too late in the combustion stroke and evidence of this can be seen in exhaust gas temperatures. They shoot up when timing is retarded because you have some of the still burning mixture being pushed out of the exhaust instead of making power.

As I said in my first post, how much running 87 octane affects you depends on driving conditions such as city vs hwy, how heavy your foot is, temperature, etc. I used to make a 4 hour trip to Vegas twice a week for a couple years and before that I made a trip to Fresno and back which was 210 miles round trip a day for Fresno and 540 miles round trip for Vegas. All freeway and I always made the trips at the same time, went the same speed on cruise control, in both summer and winter. I thought there wouldn't be much of a difference under light load of the freeway but after running it on 87 a couple times in pure freeway use, it didn't take long to realize it was cheaper to use premium. It most definitely makes a difference in mpg in the real world.

You can't just use 87 octane and switch to 91 and compare with just two tanks of fuel. Inaccurate's observation of the knock system showed it can take a day or more to put full timing back in.

So don't worry about detonation and preignition causing the loss in power. Just remember that our 11:1 compression TLs will pull timing on 87 octane and less timing means a loss in mpg and power. You can google ignition timing and mpg if you like.

I hate cars

A dirty air filter can only affect power on a fuel injected car. It has no effect on mpg.

High octane does not burn more efficiently than low octane. There is no change in hydrocarbons unless you're testing it under load and timing has to be retarded on the lower octane. That's why if you run a car that only requires 87 octane on 91 octane, you don't gain or lose power.

pohljm

I think that is "carbureted"

I hate cars

Yep. If it's carbureted a dirty air filter will act as a choke, richening the mixture. With feedback fuel injection nothing changes as the calculation is based off of manifold pressure or mass air meter which are downstream of the filter plus the 02 sensors are in place to check and correct that calculation if need be via fuel trim. It's one of those old myths left over from the carburetor days just like the one where you can't mix synthetic and regular oils which hasn't been true since the '70s.

Turbonut

iTrader: (1)

After much research, and one can read from the product engineers and not Forum members, that mileage will not be affected, and performance, although maybe 5% decrease would not be noticed by most. Even Porsche and BMW admit that regular can be used in their vehicles and no problems as there are places in the world that high test or premium isn't available and the cars run fine. Personally, can't see how mpg can drop as the A/F ratios will be maintained by the ecu and reduced performance would be negligible.

SamDoe1

You got taken for a ride. There's no way your cylinders had any carbon build up at all. The use of any good quality gasoline would have prevented any buildup. The fact that she used 87 was irrelevant.

It has nothing to do with efficiency or energy content or burn temperature. There was just a thread on this, please go read it.

I hate cars

Air fuel ratios are irrelevant, they stay the same regardless of octane.

Detonation decreases power and mpg.

Pre-ignition decreases power and mpg.

Pulling timing decreases power and mpg.

The combination of timing retard and detonation or pre-ignition results in lower mpg and power.

I don't know how many times I have to repeat myself.

How can the octane not matter in a car that's designed to run on premium? If it makes no difference in power and mpg, why do they suggest premium? It's certainly not to increase sales.

Being able to run regular without damage is not the same as being able to run regular and retain the same mileage and power as premium. Some "forum members" have access to people in the industry and not google, along with their own research. I've done the long term mpg tests under very repeatable conditions. I've done the research with the scanner hooked up to verify the TL most definitely retards timing on 87. It even retards the timing on 91 a little.

I thought you of all people would understand what retarded timing and detonation would do to mpg and power but you will disagree with pretty much anything I say so I totally understand where you're coming from.

Since according to you there's no decrease in power and mpg and it's perfectly safe to run on 87 octane, do you suggest every TL owner run on 87? What do you have in your tank right now?

I hate cars

Good to see you back.

Turbonut

iTrader: (1)

Premium Required? Not Necessarily

At today’s prices, it’s understandable that drivers accustomed to filling their gas tanks with premium would be looking for ways to ease the financial pain.

Some relief may be as close as their next fill-up. Switching from premium-grade to regular unleaded can save several dollars on each tankful, given an average price difference of about 30 cents a gallon, according to end-of-July figures compiled by AAA.

While using gasoline that carried a lower octane rating than the engine required was once a sure path to disaster, that is no longer the case. Nearly all automobiles sold in the United States since the 1990s will happily run on regular-grade 87-octane gasoline without causing engine damage, a benefit of the electronic controls that now manage all engine functions.

The octane number posted on the pump is a measure of a gasoline blend’s resistance to a condition called knocking. The knocking sound — a rattling noise made by an engine under load, familiar to drivers of older cars — is a result of out-of-control combustion, the mixture of air and fuel burning erratically. The explosion rings the metal of the engine block like a bell.

The higher the octane rating, the more temperature and pressure the gasoline can withstand before it ignites on its own, rather than when it is set off by the spark plug. An engine that calls for premium gas typically has a higher compression ratio — it squeezes the air and fuel mixture to higher pressures — which can improve both fuel economy and power output. But such an engine requires the higher octane rating to run properly.

Before the switch to fuel injection and computerized controls, engines were subject to damage from prolonged knocking. But today’s engine management systems incorporate electronic knock sensors, which detect the condition and adjust the ignition to stop the problem. As a result, it is almost impossible to hurt a current engine by using 87-octane fuel, industry experts say.

“Modern engines prevent the damage from happening before it starts,” said Patrick Kelly, a fuels analyst with the American Petroleum Institute. “It wouldn’t impact fuel economy. And it wouldn’t impact the emissions. What it would impact is the performance.”

Of course, owners who do not heed the automakers’ recommendations may face consequences — the potential voiding of warranties, for instance. But for the most part, manufacturers’ fuel recommendations include some wiggle room.

Porsche, for example, acknowledges that any of its modern production cars can be run on regular fuel without the risk of damage.

A spokesman for Porsche North America, Tony Fouladpour, added a caveat. “If you want the car to perform at its maximum capability, the best choice would not be 87,” he said. “But we do not forbid it.”

Specifying premium fuel lets a car manufacturer squeeze out more horsepower. BMW, for example, recommends that all the cars it sells in the United States use premium fuel, but they will run on regular.

“There generally isn’t any harm done to the engine by using lower-octane fuel,” said a BMW spokesman, Thomas Plucinsky. “Because our engines do have very good forms of knock sensing and are able to deal with lower-octane fuels, you will not have any drivability issues. You will, however, lose some of the performance.”

How much of a loss? Some indication can be found in the peak horsepower numbers Hyundai recently released for its new Genesis sedan. On premium, the 4.6-liter V-8 engine is rated at 375 horsepower. On 87-octane regular, it is 368.

That seven-horsepower difference — less than 2 percent — seems a small penalty for saving 30 cents a gallon, especially when you can regain that performance simply by filling up with premium.

Does using lower-octane fuel reduce mileage or increase emissions, as some drivers believe? Not according to the Environmental Protection Agency. “E.P.A. fuels engineers say that there isn’t a meaningful difference between regular and premium gasoline,” said Dale Kemery, a spokesman for the agency.

Still, the warning from some automakers can give an owner pause at the pump. The manual for the Smart Fortwo repeats the warning issued for other vehicles sold by Mercedes-Benz: “To maintain the engine’s durability and performance, premium unleaded gasoline must be used.”

But even those stern words may have some room for interpretation. Dave Schembri, president of Smart USA, told John Schwartz, a reporter who was writing for this section’s blog about his experiences in buying a Smart, that he should not worry.

“You could use regular gas — there’s no damage to the car,” Mr. Schembri said.

Turbonut

iTrader: (1)

Why use premium gas when regular will do?

Marti Mayne once fueled her low-octane Subaru with high-octane gas. Not now. Premium-gas prices "went sky high, and now I just use low grade" to motor around Yarmouth, Maine, where she runs a marketing business.

Cost differences between regular and premium is as plain as, well, the sign at the station, like this one in Chicago.
By Scott Olson, Getty Images

When prices dropped earlier this year, she stuck with cheaper fuel because "I don't think that my car runs any differently on high, medium or lower grade."

She's right. Engines designed for regular fuel don't improve on premium and sometimes run worse. And today's engines designed for premium run fine on regular, too, their makers say, though power declines slightly. (Background: About Octane ratings)

But premium lovers are passionate. "I would simply curtail driving rather than switch grades," says Bill Teater of Mount Vernon, Ohio, who puts high-test in both his Cadillacs, though only one recommends it. He's sure both the DeVille and the Escalade run rough and lack pep on regular.

Prejudice and preference aside, engineers, scientists and the federal government say there's little need for premium.

When fuel's cheap, motorists are willing to pay 20 cents or so more for premium. But as gas prices sneak back up, the mental wrangle begins anew over whether it's OK to burn cheaper, regular-grade gas.
The answer almost always is yes.

"I personally use regular even though my owner's manual says you'll get better performance with premium," says Lewis Gibbs, consulting engineer and 45-year veteran at Chevron oil company. He's chairman of Technical Committee 7 on Fuels, part of the Society of Automotive Engineers (SAE) Fuels & Lubricants Council. Gibbs knows gas.

"My wife runs midgrade (89 octane) in her car, and it's a turbocharged engine" meant for 91-octane premium, he says.

Premium — gasoline having an octane rating 91 or higher — is just 12.1% of sales, and well below the modern high of 20.3% years ago according to industry and government data. Despite the allure of premium, once they abandon it, most motorists don't come back, the data suggest.

For every dime increase in the price, sales of premium gas drop 1%, Bob Johnson, general manager of gasoline and environmental services for the 7-Eleven chain, figures, based on data back to 1998.

The main advantage of premium-grade gas is that it allows automakers to advertise a few more horsepower by designing and tuning engines to take advantage of premium's anti-knock properties. But auto engineers generally agree that if you use regular in a premium engine, the power loss is so slight, most drivers can't tell.

"I go back and forth, and I'm hard-pressed to notice" whether there's regular or premium in the tank, says Jeff Jetter, principal chemist at Honda Research and Development Americas. He drives an Acura designed for premium.

Import brands, especially, use premium fuel to distinguish their upmarket models. Most Toyotas, for instance, are designed to run on regular or midgrade, while the automaker's Lexus luxury brand prefers premium. Same with Honda and its Acura luxury line.

"Generally, the more expensive the vehicle, the higher the expectation for performance and the more the customer is willing to pay for fuel," says Pete Haidos, head of product planning for Nissan in the USA.

Actually, the price debate is nearly worthless. At 20 cents more for premium, pumping 20 gallons of it instead of regular would cost $4 more. Annually, that's a difference of $171 for a vehicle that averages 14 miles per gallon — as some big sport-utility vehicles do — and is driven 12,000 miles a year.

Gasoline retailers and refiners like high-test because it's more profitable than regular-grade gas is. The retailer paid about 8 cents more for the premium you pay 20 cents more for — though that margin can swing wildly. Refiners make a few cents a gallon more on premium than on regular when they sell to wholesale distributors.

As long as it's clean

Profit is meaningless to the modern engine, which, regardless of what's specified in the owner's manual, hardly cares what you use — as long as it's clean.

Today's engines use highly evolved versions of a device called a knock sensor to adjust settings automatically for low-octane gas. And more engine control computers have adequate memory to allow separate sets of instructions for various octanes. The engine control computers keep pushing to maximize performance on whatever grade of fuel is used.

Extreme pressure inside the cylinders causes knock, which is the sound of the pistons literally rattling inside the cylinders. Too much too long can damage the engine. A little now and then won't.

The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.

Automakers say they don't test premium engines on regular to check the difference, but some auto engineers estimate that power declines roughly 5%.

"We can't guarantee the vehicle will perform as specified if other than premium fuel is used," says Mercedes-Benz spokeswoman Michelle Murad. All U.S. Mercedes engines specify premium.

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches.

Premium, in fact, sometimes is worse fuel than regular. It resists knock because it's harder to ignite than lower-octane fuels. As a result, some engines won't start as quickly or run as smoothly on premium, notes Gibbs, the SAE fuel expert.

High-test does have a potential fuel economy benefit. It is slightly denser than lower-octane gas, meaning there's a little more energy in a gallon. But the small difference is hard to measure in real-world use, and that same density can contribute to undesirable buildup of waste products inside the engine.

No data show that engines designed strictly for regular run better or longer on premium.

The Federal Trade Commission, in a consumer notice, emphasizes: "(I)n most cases, using a higher-octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner."

There is "no way of taking advantage of premium in a regular-grade car," says Furey.

"There is no gain. You're wasting money," insists Jim Blenkarn, in charge of powertrains at Nissan in the USA.

"No customer should ever be deluded into thinking there's any value in buying a higher grade of octane than we specify," says Toyota's Paul Williamsen, technical expert and trainer.

But premium retains a mystique.

Even Mayne, the sensible Subaru owner who has switched to regular, says she'll buy premium when her neighborhood station has a special price. "It's my perception that I might get better gas mileage or that it might be better for my engine," she says.

"I would stop driving rather than use a lower grade of gasoline," says Andrew Martschenko of Boston, who drives a 2003 Nissan Maxima. Nissan says premium is "recommended" for that engine — automaker code for regular is OK, but you'll only get the advertised power on premium.

If the price difference between regular and premium grew to $1, Martschenko says, "Then I might consider trading down" to regular.

Guilt plays a part

Some people feel almost guilty, as if they are abusing their cars, when they don't burn premium, says gasoline retailer Jay Ricker, president of Ricker Oil of Anderson, Ind., which operates 28 stations. "They go all the way down to 87 (octane), but maybe every fourth tank they put in the good stuff."

Sam Turner has seen the appeal, too. He's president of Favorite Markets of Dalton, Ga., which operates 139 outlets in three states.

He recalls visiting one of his stations during a price war with a nearby station, which had cut the price of premium to just 4 cents more than regular, instead of the usual 20-cent difference.

"A customer was waiting and asked me if I was going to match the guy across the street. I said, 'Yeah,' and he said, 'Good. For 4 cents, I'm gonna buy super.' "

Brock79

Here is a quick question that no one has even asked or thought about. Is the 91 octane really 91 octane? The same goes for 87 and any other premium octane out there. I worked at a refinery in NJ for a year during my first stint and 6 months for the second. I do general contract work for them. I discussed these octane ratings with some of the higher ups, I was pretty amazed at first by what I was told, then it sunk in and realized its an oil company of course they are going to scam us. Anyways the info I got was pretty much that no one gas company matches the others as far as octane. What's 91 at BP might be 89 at Exxon, and no on. The higher premiums like Sunco 94 is more like a 92 they said. Even worse the no name and off brand places 91 is really more like 87 and there 87 is closer to 84-85. The reason for this is the cleaner they run through the system to get on companies dye out to change over to the next dye. By the way this one refinery sources almost all of the fuel in the northeast, no matter the brand or gas station. They just change the formula to the companies specs. So most people are likely not even putting a true 91 in their tanks, you could be paying a premium price for an 89 and the guy across the street is getting 90 for the same price.

nfnsquared

Assuming they are all using the (R + M)/2 rating system, they should all be the same. e.g. Sunoco 92 should be equal in octane to Shell 92....

I hate cars

Thanks for the Spam turbonut. Thanks also for the explanation of octane, I had no idea what octane was lol.

You're doing your usual twisting of words and putting words in my mouth, something you specialize in.

If you read what I wrote long before you came in this thread, I said running lower octane will not result in catastrophic failure. It can mean more cylinder/ring and rod bearing wear over the course of 200,000 miles. The engine damage debate was over long before you came along.

I also stated you will not gain or lose power or mpg by running a higher than required octane so again, you're late to the game.

Thank you for proving my point that you lose power on 87 octane. Now you need to connect the dots to the mpg side.

If you can answer the question of why power is reduced when you run a lower octane in a car that requires premium, you might be able to apply that to the mpg loss as well. Let's see if you can make the connection.

I might as well give you the answer. So, when timing is retarded, power is lost. To counter that loss in power the driver must give it more throttle. More throttle equals more air and fuel being burned. It's not making best use of the air and fuel it has because timing is too late and the in cylinder pressure rise comes too late. You're burning the same amount of fuel but you're making less power with it.

You can not have a loss in power due to timing reduction without a corresponding loss in mpg.


So again, you get worse mpg and power for a few bucks at the pump. You're talking a savings of $4 on a fill up. Are there really people out there that own a TL that are so cheap that they can't afford an additional $4 twice a month even when it means filling up less often? You're talking a
5-8% difference, something that can easily be made up in the mpg department.

Can you counter in your own words or will you quote more google nonsense?

One more thing, I'm going to pick your google crap apart when I get to a computer. There is so much misinformation from those so called engineers. You should be a little more critical of where you get your information from.

They have the balls to say that Honda specifies regular in their Honda models but premium in their upscale Acura models to make them seem more prestigious? I guess they forgot the Accord that runs on regular had 10:1 compression while the TL had 11:1 compression. It's just a sea of misinformation written by biased journalists that know nothing about cars.

I can't believe you would post so much crap but I know why you did it.

So again, what's in your tank?

nfnsquared

^^^Wow dude, once again you proved that you are incapable of having a civil discussion. Throughout this thread, people have been posting their position in a very civil manner without name calling until you came along and showed your immaturity. Let's hope it stops with that post.

Let's see if you can engage in the discussion and express your view without belittling or name calling or threats.

GKinColo08TL

IHC...I think you've handled this quite well...I've seen your posts numerous times about gas octanes etc...and to my research your info has always been accurate. Also, I didn't see you call anyone names either. I for one appreciate your knowledge about many different topics.

I hate cars

Name calling? Threats? Where? I let turbonut start with the belittling, I just followed suit but I wouldn't expect you to acknowledge that. The discussion was going fine with both sides being expressed until you two showed up. Show me the name calling and the threats. I can start making remarks toward the two of you that only the 3 of us will get as you guys do and then act innocent when you react.


Don't give me that crap about being civil. The two of you have played this game for years. You post some nonsense, push some buttons, and then back off while the other plays cheerleader or instigator and try and turn it around on me. You know exactly what turbonut did because you do it yourself all the time. You guys will argue any point to go against me even if it's as ridiculous as running 87 in your TL when your history on this board shows you're against it. This has been going on for years, nothing new here.

If you read that article with an open mind you would see how twisted it was with almost zero facts and a lot of opinion disguised as fact. It gets old having to clean up the shit you guys sling. I could make a full time job of it.

I've refused to give in to the google education as you guys do. Half the stuff out there no matter how well written is BS. I try to stay away from it except for SAE white papers because it doesn't help anyone to repost bad information. I most definitely don't repost articles as my own writing and without citing the author or a link to the website it came from as someone did. I wonder how many articles I can find in favor of running premium.

ggesq

iTrader: (1)

I don't see name calling or threats by anyone. Let's keep this thread on track as opposed to having a history lesson on the interactions between members. I'm well aware as are the other mods that know you guys in regards to the history between you all. Thanks.

pohljm

try again......same crap different day!

ggesq

iTrader: (1)

nfn, your post was deleted. It was deleted because I'm keeping this thread on track early. If you'd like to repost the last part of your previous post without the back and forth with IHC by all means please do so. Thanks.

Acura-OC

I hate cars,

You've explained it 4 or 5 times no reasons to repeat it anymore, I got it thank you very much.

I am using 91 and will keep using 91 just calm down and listen for a second.

You keep going to theory assuming (and that is a big assumption) that TL engine with 11:1 compression ratio will detonate earlier than it suppose to therefore all your bullet points will happen. What I am saying that it will not. For example Toyota makes 3.3 litter engine with 10.8:1 compression ratio that doesn't require premium and it is not even recommended. Not only that it also requires certain temperature for gas to detonate.

I am just curious to know if for every day normal driving conditions there is any noticeable difference. I think not. I do not think that small difference from 87 to 91 is enough to make a difference. I really do not know maybe it is because there is point at which 87 will detonate.

Sonata 11.3:1 doesn't require premium
Cobalt, Malibu, and Saturn Vue, 11.4:1
Equinox 11.7:1

I hate cars

In response to a member's request for real world information/data, I responded with real world information from running 87 octane during highway driving. Not from just one tank of 87, but from 48 tanks of 87. I have never advocated for the use of 87 in these posts. But the fact remains, there was no difference on MID MPG while running 87 on the highway.

So, let's talk about something I think we all agree on (at least most of us do):

1. Detonation decreases MPG
2. Pulling timing decreases MPG.

Yet from my experience from running 48 tanks of 87 gas for over 21,000 miles, there was no difference in MID MPG.

So based on my substantial real world experience, one can only assume that running 87 gas on the highway (in a 3G TL) has neglible effect on detonation and knock...
I'll answer this...

As I said earlier (this is the 3rd time I'm repeating myself in one thread), the conditions in which 87 is run have a huge influence on whether or not you can get away with it. Temperature, driving style, speed, etc all have an effect. I too drove my car at about the same time of day, filled up at the same station and made the same 460 mile trip twice a week, I even posted on it back in the day on here. I was surprised there was a mpg difference in 87 and 91 under light load. Temps were generally 90-113 in the summertime and there were some mild hills.

Taking off from a redlight requires 2-5x as much throttle as cruising at 70mph. Unless you can cruise steady state on flat ground in 60 degree weather, you will see a decline in mpg on 87 octane as I did. To take it a step farther, I got another boost in mpg when going higher than 91, showing it's still pulling timing even on the freeway on 91 in my conditions.

Also to add to my experience was driving for a couple weeks with the scanner hooked up monitoring knock retard and there most definitely was timing being pulled.

ggesq

iTrader: (1)

In fairness, IHC, one of your posts was deleted too.

On topic guise...

I hate cars

You forget one huge point. Those with the very high compression ratios are direct injection which allows substantially higher compression and boost on a given octane. That's the number one selling point of direct injection. You can't compare our port injected TLs, it's apples to oranges.

It is not a theory that the TL detonates on 87. I've had the scanner on it. Hell, it detonates on 91 octane under the right conditions. Others have seen the same thing. The TL detonates on 87 octane period. If you have 87 and you're driving normally, the knock sensor is working overtime.

It is not a small difference between 87 and 91 when you have a car with port fuel injection and 11:1 compression that has some detonation even on 91. I'm the original owner and I've been forced to run about 4 tanks of 87 since the car was new, usually due to poor planning. The car surges and feels gutless when you attempt to drive it normal. It feels ok as long as you put your foot in it and you keep rpms above 4,000rpm.

I hate cars

Sorry.

I hate cars

Onto this abortion....

About the author of this article:
"Dexter Ford writes about fast cars, hot motorcycles, sustainable transport, solar power, avant-garde and green architecture, adventure, travel and other fast-moving topics for some of the world's most-respected newspapers, magazines and websites. And creates influential advertising, branding, naming and interactive/web work for Mercedes-Benz, Lexus, Ferrari, Infiniti, Nissan, Acura, Oracle, Siemens Medical, Indian Motorcycles and other major brands."

Reading more of his stuff, he has a liberal green and underlying promotion in most of his writings. To say his writings are biased is an understatement but let's pick it apart so the mis-information can stop.....for now. This thing is one huge contradiction.



Here's the problem I have with this... If knock could destroy an engine made in the '90s it most certainly can destroy a modern engine especially those designed with less drag thinner rings, higher top rings, light low friction pistons, etc. The electronics attempt to keep knock in check and they do a good job. However, the knock system is reactive. The knock has to occur in the first place in order for the sensor to hear it and retard timing. To stop knock once it starts, you have to remove more timing than if it never started in the first place.
1,600hz to be exact.

The important thing to remember here is knock is damaging long before it's audible to the human ear. Since I know my GN so inimatly I know that 13 degrees of knock retard is at my hearing threshold and it's a pretty quiet car. By the time you've hit 13 degrees you've blown a head gasket. The lower powered TL can get away with some audible knock but as I said at least twice in this thread it's a cumulative effect. Instead of blowing a head gasket or knocking out a ring land the engine never blows up but the detonation does hammer away at the pistons, rings, and rod bearings. Over time as you get into high mileage the effects of continuous detonation will start to take it's toll.
Right here. I hope everyone reads the above 10 times. Keep in mind he says engine designed for premium fuel with high compression ratios can improve BOTH fuel economy and power. Let's keep reading and see how long he takes to contradict himself.
Mostly true but again, it's a reactive system, knock has to occur. Once the timing is pulled, it's not pulled for good. The ECU continually tests the waters to try and get full timing back in as quickly as possible for best power and mpg.
Prevent the damage before it does instant damage but it can't predict knock. This is where Mr. Patrick Kelly is wrong. You can't impact power without impacting mpg. You're pulling timing, the engine becomes less efficient so it makes both less power and loses mpg. Let's say it another way. So they admit the engine loses power so that part is a given. Now what happens when you want to accelerate at a certain rate and the ECU pulls timing because you're on 87 octane causing you to lose some power? You give it more throttle to get the rate of acceleration you want. You open the throttle plate to allow more air and fuel into the engine just to make up for the power loss due to timing being pulled.
The first part was fact, second was the author's opinion. He states running a lower than recommended octane will void some warranties yet states multiple times you can't hurt a modern engine by running it on low octane.
Remember the part in the beginning where I said he would contradict himself, here it is. So let me get this straight, according to this guy, designing an engine to run on premium can increase mpg but running regular in it won't decrease mpg????? Am I the only one that thinks he's full of shit?
Hmmm. The manufacturer repeats a warning to use premium to "MAINTAIN THE ENGINE'S DURABILITY" Again, it's not going to blow up but it's not going to last as long either.
And I always believe someone who's in a position to make money by selling more cars.

My friend has had a few Mercedes CL65 AMG cars, this is the twin turbo V12. He put 87 octane in one of them one time and we were both laughing. The ECU basically pulls the plug on power. Boost dropped by nearly half and the car felt like it lost half it's power. We never paid attention to mpg in that car since it was usually at full throttle or at idle but it was a joke on 87 octane.


Something I found by accident, from a Chrysler Crossfire's owners manual I saw when looking for the author of this article:

"Owners Manual
Starting and Operating
Page 149

FUEL REQUIREMENTS

Your engine is designed to meet all emissions
regulations and provide satisfactory
fuel economy and optimum performance
when using high quality unleaded gasoline
having an octane rating of 91 or
higher. DaimlerChrysler Corporation requires
the use of 91 octane or higher premium fuel to
minimize the potential for engine damage.

Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and should be reported to
your authorized dealer immediately. Engine damage
resulting from operating with a heavy spark knock may
not be covered by the new vehicle warranty.
Poor quality gasoline can cause problems such as hard
starting, stalling and stumble. If you experience these
problems, try another brand of gasoline before considering
service for the vehicle.

Over 60 automobile manufacturers around the world
have issued and endorsed consistent gasoline specifications
(the World Wide Fuel Charter, WWFC) to define
engine performance, and durability for your vehicle."


I haven't scratched the google surface yet so let's not go there.

I hate cars

This one is even worse. You have to love anything written by USA Today writer James R. Healey, I'm guessing he's not a car guy.


Cool, so we're already starting out by withholding the model of car. Is it a regular Forester with the naturally aspirated engine that will run just fine on regular or is it a WRX turbo car that needs premium. I guess we'll never know but it's a safe assumption the model was withheld to keep readers guessing, thinking it's a turbo model.

That's good to know. Some unknown chick in some unknown car doesn't think her car runs much differently on regular or premium. Thanks for the bombshell.
I referenced his reference above and wow, I can't wait to tear that one apart. If you think these two articles were full of crap, they're nothing. This is what I mean about believing everything you read on google. You have an article published by a major newspaper by a guy who knows nothing about cars referencing another article that has some of the worst information I've ever come across.

But yeah, there's no performance to be gained if the engine can't take advantage of higher octanes but, despite what this moron says, you do not lose power from running high octane in a car thats designed for low octane, you just waste money.
So this know nothing author chalks the car owner's observations up to prejudice. Well at least he's passionate according to the author.

This last sentence is a blanket statement if I've ever seen one.
He may know a lot about gas but he's not that smart when it comes to cars.
The decline is because knock is rarely audible anymore. It's still happening when you run regular in a car that's supposed to have premium but the ECU keeps it to a level that's hard to hear. Most people know nothing about cars and especially about what goes on inside the engine so if there's not huge flashing neon sign like audible pinging telling them to run a better gasoline, they're taking the cheap route.
It would be nice to know which "engineers" are making this claim. Remember in the other article it said engines designed for premium can get better power and mpg.
Again, it's an Acura. What kind of Acura I wonder? What climate does he live in? What type of driving does he do? Is it an underpowered 4 banger where it's so slow to begin with you can't tell the difference?
Yep, our TLs require premium to distinguish them from the Accord. It can't be that the Accord ran a 10:1 compression ratio and the TL ran an 11:1 ratio during the 3G run. They don't even try to use facts.
I can afford $4 extra once a month as I do now and I had no problem affording it when I filled up twice a week. Not to mention I fill up less often with premium so I'm not actually paying more.
I don't care about their profits, not sure why the author does unless he's ...... gasp ....... biased.

No mention that the knock sensor is reactive. This guy tries to make it sound like there's an octane sensor that automatically backs off the timing when you fill up with regular and puts it back in when you switch to premium. It doesn't work that way. The computer does try and maximize performance for a given octane but if it's designed to run on 91 and the computer tries to maximize performance on 87, it's also trying to maximize performance on 91.
It absolutely is not the pistons rattling for God's sake. It's an uncontrolled explosion or two flame fronts colliding in the cylinder. It's this explosion that causes the harmonics in the block around 1,600hz in both iron and aluminum. I bring up 1.6khz because that's the frequency that goes through the block when detonation occurs. How can a piston rattle at 1,600hz every time regardless of rpm? It can't.

He's right that too much too long will damage the engine. However, a little now and then will add up over the life of the car and may or may not ever bite you in the ass.
Wait, did a chemist really just say that an electronic device can't keep up with a mechanical device? The reaction speed of the electronics is thousands of times quicker than the supercharger is to full boost. The ECU can do millions of calculations in the time it takes to hit full boost.

Last time I checked, superchargers and turbochargers force feed AIR and not FUEL into the engine. I'm pretty sure the injectors force feed the fuel. WTF??? How can someone post this crap with no regard to it's accuracy?
Hmmm. I could swear the previous article said manufacturers can void warranties. I wonder which article is telling the truth. Probably neither. I wonder how much "perhaps a little bit of performance that a customer wouldn't really even notice" is. If it's so little, why go to the trouble of specifying premium in the first place. Requiring premium certainly does not help sales.
I absolutely guarantee they do test on regular fuel. I know this first hand from one of the Ford modular design engineers.
Anyone have a hard time starting their TL? Didn't think so. My GN sits on a tank of 110 leaded fuel with a low 8.5:1 compression ratio and it fires off just as quickly on 110 and even 116 octane as it does on 87. We're not talking carbureted cars here.
Did he say premium does have a potential fuel economy benefit?????? As much as I would like to use this to prove my point, it's utter BS. Premium does not have more energy content and it does not leave any more or any less "buildup of waste products inside the engine" lol.
I think we're all pretty clear on this.

Finally something I agree with. Well, with the exception of the Nissan engineer when they're notorious for knocking extremely badly. The fiancee's Murano knocks embarrassingly loud under light throttle. I took it in 3 times, had to show them how to look at timing and knock retard and finally gave up and fixed it myself. It was a dirty MAF that seems to need cleaning every year even with a factory air filter.
I'm not sure why the above was included, what's the point exactly? Is it trying to analyze the mind of a premium lover? Lol.
That answered my question.
Depending on the car, maybe they should feel guilty, or maybe they shouldn't. You can't make a blanket statement.
Okaaaay. What a horrible article.

I hate cars

I can't help myself, I have to post this article. This was a reference used in the article above. This is some of the worst crap I've ever read but the website is pretty and professional looking with advertisements so it must be legit....
http://www.examiner.com/article/trut...octane-ratings

Clear up myths? More like spread old myths and even create new ones. Read on for a good laugh.
Octane has absolutely NOTHING to do with the speed at which fuel burns. My 110 octane race gas was chosen over the 116 octane because it has a quicker burn rate than 116 and 91. Burn rate and octane are not remotely related, take a look at wiki if needed.
OMG. Knocking occurs when the air/fuel explodes instead of a controlled burn. It has nothing to do with combustion occurring too early. "Knock" does not break valves. I say "knock" because the author clearly does not know the difference between detonation and pre-ignition. I didn't realize "efficient cars use less energy to ignite fuel and therefore need a lower rating". WTF is this nonsense? I literally can't even guess what he's trying to get at.
The first sentence is almost right despite using the wrong words to describe the AFR. I like that more fuel will "produce more combustions and therefore more engine revolutions and ultimately a faster car" Can someone translate this?
So let me get this straight. If an engine uses less air and fuel, you can use a lower octane? My little 4.2L turbo engine should be running 80 octane compared to a Viper's 8L V10. And low octane gives higher efficiency, got it.

A turbocharged vehicle has a huge advantage over a naturally aspirated vehicle at high elevations. It is the exact opposite of what this moron is saying. I've seen stock GNs beat stock Vipers in Colorado because the turbo is forcing the same amount of air into the engine at altitude as it does at sea level while the other cars lose some serious power.
I don't know where to start. I give up. I wish this kind of crap could be taken off the internet. It looks like it was written by a Dumbass lol.

The sad part is this article was used as a reference by a major newspaper.

pohljm

Whats the best cold air intake?

6 MT

2-3mpg (or roughly 50 miles/tank) difference on the mid over the same route and type of driving. Consistent over the last 70k miles on my car. I understand the theory, but can't argue with real world application/experience. Worth noting driving mix is about 50/50 local roads and highways.

Acura-OC

My TL has a little over 83K miles on it. Did anyone had any smog test done at about same millage? I will fill up with 87 and will take it for a smog test for sporting interest so we could compare it to your results using 91. I know that there is one person that has already done it and later laughed about it with his buddy under the blankets. But this time I am looking for a true unbiased experiment. My car is due for registration and smog check so I will fill up and drive for a few days before taking it to a test station just to make sure it burns the bad stuff.

Jackass

If the state isn't checking the stations and refineries, then they aren't doing their jobs. My parents own a gas station (in MO) and they get checked more than once a year to verify that the pumps are accurate as well as that their blends meet the correct ratings being advertised and sold. They actually don't even sell a mid-grade anymore because their "87" octane is actually closer to 89 once the Ethanol is blended in. Their "91" is Ethanol free.

Yes most gas all comes from the same refineries, it is usually just the additives that are added at the local station that differ between brands.

I hate cars

It shouldn't make a difference. You can't compare two different cars, you need a larger sample size to do so. You can smog your car twice, once with premium and once with regular. Does your state use a dyno and test it under load?

I had mine tested when new with the 3rd cat removed and it was very clean. I had it tested again when it was actually due with over 100,00 miles and it was even cleaner. The hydrocarbons were even lower than new at zero. NOx was a little on the high side which tells me it was on the lean side most likely.

Who was laughing under blankets???