Start switching to 87 octane gas.

[greasefingers]

From what I have read, this is very true for most of the stations. Logistics /transportation is a huge cost. The articles, for example, point out that Exxon gasoline may not be indeed Exxon gas if the timing is wrong. For example: they will not let a station run dry, so if no filling trucks are in the area they may choose to purchase gas from a different supplier.

 

[noodlesfusion]

Yesterday is my first time to use 87 octane gas for my 4Runner. Before that, I always use 93 octane gas. The reason for switching to another lower octane gas is the high gas price. At my area, 93 octane gas is $2.58/g. I know it's nothing comparing to California. However, filling up a tank cost more than $50 is too much for me. I'm planning to keep $200/month on gas.

I haven't noticed any knocking or slow start on the engine yet. I am thinking about getting two 87 octane and one 93 octane cycle.

--Thats why I got myself a Gixxer 6... 10 bucks per tank is good enough for me

-Yeah gas prices suck... i was filling chevron 91 @ $2.49/gallon..now its jumped up to $2.69/gallon now in under a month so i switched to 89.... same stuff and milage... i use the ac all the time cuz its been so friggen hot.. but same milage as when i was runnin 91...

if your car doesnt need hi octane gas just so long as there are detergents in the gas.. shouldnt it be okay to use 87 then?

 

[Iowa4Runner]

Iowa4Runner,

You did make this statement? What does it mean?

Koz

Earlier, out of the blue you said, "The energy difference between regular and premium fuel is so minimal..." I can only assume you said this because you think since regular and premium fuel have the same energy, they'll give your engine the same performance. I wanted to be sure this was your reason, that's why I asked what your point was, why it was significant.

Like it or not, even though they have the same energy, it is possible for your engine deliver more power on premium vs. regular. Why? Because internal combustion engines are very inefficient from an energy usage standpoint. Less than half of a fuel's energy is converted to mechanical power, most of it is thrown away as heat. There's no energy magic happing with premium fuel, your car simply is able to make use of a little more and throw away a little less.

Retarding the timing on an engine is going to reduce it's power output right? Be aware that this does not involve a change in fuel energy input, only a change in mechanical energy output from the engine. So if you're running under hot, heavy load conditions, where detonation is likely, then a low octane fuel will require retarding the ignition to avoid knocking. High octane fuel will allow your engine to keep it's optimum timing advance. This is how there can be a power output difference between two fuels of the same energy content.

I'm well aware of the fact that octane is not a measure of energy, power, or efficiency. It's simply an anti-knock index. BUT this does not mean there can't be a correlation between octane and engine behavior. All there needs to be, for a correlation to exist, is some kind cause and effect relationship.

So what's the bottom line about 4Runners and octane? There's no way to know what will happen if you switch from 87 regular to 92 premium, unless you actually try it. There's no guarantee you'll notice a performance increase and there's no guarantee that you won't. Knock sensors are more sensitive than our ears so don't fall for the old "if it's not knocking, then more octane won't help" routine. That's outdated thinking. Your computer will "hear" it and retard the timing before you get a chance to notice the first ping.

What do I use? 89 octane, because it's cheaper than 87, no joke. Iowa is a strange place...

 

[Koz]

Like it or not, even though they have the same energy, it is possible for your engine deliver more power on premium vs. regular. Why? Because internal combustion engines are very inefficient from an energy usage standpoint.

I think we are beating a dead horse here! We both agree that reg & premium fuel basically have the same amount of energy. We both agree that higher octane fuel has more resistance to pre-ignition, which may reduce the need for the ECU to retard the timing. We both agree that the use of premium fuel will help prevent engine damage do to pre-ignition. I think we can both agree that the 4Runner engines may not need premium fuel.

All that said, I use premium fuel to play it safe because I have a heavy foot.

Koz

 

[Iowa4Runner]

I think we are beating a dead horse here! We both agree that reg & premium fuel basically have the same amount of energy. We both agree that higher octane fuel has more resistance to pre-ignition, which may reduce the need for the ECU to retard the timing. We both agree that the use of premium fuel will help prevent engine damage do to pre-ignition. I think we can both agree that the 4Runner engines may not need premium fuel.

All that said, I use premium fuel to play it safe because I have a heavy foot.

Koz

You don't need premium fuel to prevent engine damage, the knock sensor takes care of this for you.

So answer me this.... In your opinion is it possible, under the right circumstances, for a 4Runner engine to produce more power on premium fuel vs. regular?

 

[LeeRunner]

This is from Yotatech.com

I follow the details of my owners manual recommendation for gas.

Here is something from Yotatech.com

+++++++++++++++++++++++++++++

while running higher octane gasoline will reduce pining, it can actually *increase* carbon build up.

higher octane means the fuel is harder to burn (which is why it stops pinging).

carbon build-up is caused by incomplete combustion.

fuel harder to burn = more likelihood of incomplete combustion = carbon build-up.

engines are designed to run gasoline with a specific octane rating. if you run an octane level higher than what the engine is designed for, you can get incomplete combustion (because the gasoline is harder the burn than the engine was designed for, so the engine does not completely burn it).

the result, over the long-term, is carbon build-up.

now, once you already have carbon build-up, you may need to switch to (or continue running) higher octane fuel. the reason is that the carbon build up effectively reduces the volume of the combustion chamber, thereby raising the compression ratio (higher compression requires higher octane). also, the carbon deposits retain heat, thereby raising the temperature of the combustion chamber.

however, if you do not have pinging problems and your engine is stock, you should run the recommended octane level, not higher or lower.

http://yotatech.com/showthread.php?p=657272#post657272

 

[jwyshrek]

Wow...didn't realize there was such a passion for gas!?

Well, here is my 2 cents...

87 octane is 'easier' to ignite than 91/93 octane.

Under a 'heavy load' (towing, hard acceleration, etc.), the 87 octane is more likely to cause preignition...or what is commonly referred to as 'knocking' (or valve clatter).

Most modern engines have 'knock sensors', that when knocks are detected by the computer, it retards the timing.

From my understanding...knocking is when the fuel air mixture ignites too soon...before the piston has completed its compression stroke. (Reason you don't hear knocking on modern engine is because the computer senses and adjusts quite fast...)

Anyway, so...what happens when you retard timing...it reduces the amount of power the engine can potentially produce...hence the the word...potentially.

So, by using higher octane you reduce the chances of knocking...preventing the retardation of timing...making the most potential power.

Now, having said that...you only get the most out of higher octane gas IF your engine was design for it...like the V8 4runner. It was design for 91/93, but it has the ability to 'adjust' itself to lower octane...and in most driving conditions you won't be able to tell the difference.

My '99 Olds Alero was design for 87 octane...putting 91/93 won't do a dam bit of good...other than make my wallet lighter.

Its too bad that cars still don't have distributors which you can turn a little to the left or right to adjust the timing...so you can see what effect timing has on engine power...and power band.

anywho...sorry if someone already posted the above...but too lazy to read the whole thread. ADD you know.

later,

 

[bryancos]

<B><I>I used to think this way in the past. That was until I happened to be near the local gasoline distributor's tank farm. When I saw a number of tankers labeled Exxon, Sunoco, Sheetz and other brands filling from the same pipe connections at the tank farm it made me stop and think. Since the tank farm was not huge (maybe 6-8 tanks) it appeared that the same gas was being loaded into different tankers that then delivered their "brand" of gas to the neighboorhood stations. If this is indeed the case, for my area, buying by brand is meaningless since it appears to be all the same gasoline.</B></I>


I've often joked that the buttons where you select what octane/grade of gasoline to pump are really just there for show... Those paying for high grade are probably getting the same gas the rest of us do, and behind the panel the hoses probably all feed from a single underground tank! I wouldn't put this past the oil companies...

 

[Koz]

So answer me this.... In your opinion is it possible, under the right circumstances, for a 4Runner engine to produce more power on premium fuel vs. regular?

Absolutely, #1 If the knock sensor detects knock the computer will retard the ignition temporarily. This temporarily reduces vehicle performance. Therefore higher octane fuel would reduce the chance of knock. Causes; Under very hot ambient temperatures, low altitudes, very dry air, rapid acceleration and/or heavy loading, such as pulling a trailer or climbing a hill, stop-and-go driving and excessive idling can cause buildup of combustion chamber deposits. Any one of these scenarios or combining of any will cause a demand for higher octane, which would provide better performance.

Koz

 

[Pistonslap]

All that said, I use premium fuel to play it safe because I have a heavy foot.

Koz

Do you think it is worth the risk of carbon build up?

I say that because I have used both and seen no noticable difference in mileage or performance. Of course everyone drive under different circumstances. I just don't think it is worth the risk of running higher octane fuel if the result could be long term performance loss.

 

[Iowa4Runner]

Absolutely, #1 If the knock sensor detects knock the computer will retard the ignition temporarily. This temporarily reduces vehicle performance. Therefore higher octane fuel would reduce the chance of knock. Causes; Under very hot ambient temperatures, low altitudes, very dry air, rapid acceleration and/or heavy loading, such as pulling a trailer or climbing a hill, stop-and-go driving and excessive idling can cause buildup of combustion chamber deposits. Any one of these scenarios or combining of any will cause a demand for higher octane, which would provide better performance.

Koz

That's what I was hoping you'd say. Now we can finally let this thread rest in peace...

 

[bulldog-yota]

Do you think it is worth the risk of carbon build up?

I say that because I have used both and seen no noticable difference in mileage or performance. Of course everyone drive under different circumstances. I just don't think it is worth the risk of running higher octane fuel if the result could be long term performance loss.

Has anybody proven higher octane causes carbon build up?

Has anybody used a dyno to test power output on exactly the same conditions for high and low octane on the 4Runner engines? This way we will know if it produces more or less power, which will also be a good indication if it will yield better fuel economy.

I know on high performance engines like the M3, Porsches, etc that they have to be detuned (produce and rated for less torque and HP) for US low octane gas. Yes even premium here is relatively low octane compared to 98 you get in Europe, but then again we pay half the price

The question is what is the actual difference for 4R engines? Some say yes some say no, but nobody has hard data to prove either point. So it seems like religion, believe what you want to believe and be happy.

 

[Northof49]

Has anybody proven higher octane causes carbon build up?

Has anybody used a dyno to test power output on exactly the same conditions for high and low octane on the 4Runner engines? This way we will know if it produces more or less power, which will also be a good indication if it will yield better fuel economy.

The question is what is the actual difference for 4R engines? Some say yes some say no, but nobody has hard data to prove either point. So it seems like religion, believe what you want to believe and be happy.

That's 1000% correct. We have at least eleventy billion threads on gas mileage, octane ratings, gas mileage and octane ratings, what octane to tow with, towing gas mileage, what octane to use while towing 2 giraffes precisely 11.67 degrees west of north through Istanbul, etc, etc.

The only thing we know for sure, is that the threads last forever, and that no one has hard data to back up there own theory.....and that everyone's theory is different.

All we know, is that no one has ever blown up a V6 or V8 in a 4rth gen from using 87 octane, and that there is the POSSIBILITY of a slight performance increase using higher octane fuel under harsh conditions. Toyota recommends at least 87......that means if you put 87 in the truck it will run normally.

I think another error many people make is assuming the highest octane possible is the best for their application. The way to make the most power with the highest efficiency is to use the lowest octane possible to acheive 0 knock/ECM timing pull......unfortunately, until someone straps one of these things on a dyno and runs different fuels while measuring knock voltage, we won't know what that is.

 

[Kanab]

I used to think this way in the past. That was until I happened to be near the local gasoline distributor's tank farm. When I saw a number of tankers labeled Exxon, Sunoco, Sheetz and other brands filling from the same pipe connections at the tank farm it made me stop and think. Since the tank farm was not huge (maybe 6-8 tanks) it appeared that the same gas was being loaded into different tankers that then delivered their "brand" of gas to the neighboorhood stations. If this is indeed the case, for my area, buying by brand is meaningless since it appears to be all the same gasoline. [/QUOTE

Same gas different additive package. Often added at the tanker truck level. There is a difference.

 

[Bluto]

Re: This is from Yotatech.com

If you run the higher octane fuel long enough and get enough carbon built up, you will increase the compression. If you increase the compression, you will need higher octane.

Here is something from Yotatech.com

+++++++++++++++++++++++++++++

the result, over the long-term, is carbon build-up.

now, once you already have carbon build-up, you may need to switch to (or continue running) higher octane fuel. the reason is that the carbon build up effectively reduces the volume of the combustion chamber, thereby raising the compression ratio (higher compression requires higher octane).
http://yotatech.com/showthread.php?p=657272#post657272

How much build-up would it take to increase the compression ratio?

I can see the build-up causing hot spots and preignition.

I'm with bulldog-yota on this. I'd like to see some faqs from the oil companies, auto manufactures, or mechanics. Not internet speculation.

More speculation...

http://yarchive.net/car/carbon_deposits.html

http://www.misterfixit.com/deton.htm

 

[Kanab]

Re: Re: This is from Yotatech.com

How much build-up would it take to increase the compression ratio?

I can see the build-up causing hot spots and preignition.

I'm with bulldog-yota on this. I'd like to see some faqs from the oil companies, auto manufactures, or mechanics. Not internet speculation.

More speculation...

http://yarchive.net/car/carbon_deposits.html

http://www.misterfixit.com/deton.htm

I had a 1995 Landcruiser that at around 100K had to start using 89 Octane and at 120K miles I had to go to 91 Octane to eliminate the pinging. I only had pinging when I was pulling steep hills and the higher octane got rid of it. I think it was carbon build-up that was causing the need to increase octane. It ran great on 87 octane for the first 90-100K miles.