Start switching to 87 octane gas.

[Iowa4Runner]

:corn:

Koz

Ahh you beat me to it. I was just about to ask when you were going to post another empty message with the dancing guy...

 

[Iowa4Runner]

Question #1: Yes and no. Of course this is hypothetical because 80 octane is about as low as it gets, but if your engine ran perfectly fine on a mythical 50 octane, you had no preignition in the conditions you were operating, then running 150 octane will not yield any improvement in performance. Now were the engine designed to run on 87 octane and you put 50 octane in and it would run on it, but pinged like crazy to a point that the timing was retarded to eliminate preignition , of course you would see an increase in performance a higher octane that does not cause preignition.

Question #2: This depends. Towing changes the operating conditions. Hearing the knocking may be impossible to detect. If it occurs and you can hear it, of course you would benefit by upping the octane. If by chance you had a scanner connected while towing and your knock sensor detected nothing, then you would not benefit at all by upping the octane.

The point I am trying to make is that correct octane is important. Anything lower will suffer from performance loss and increased engine wear, and anything higher will not increase performance and can lead to more problems down the road.

Question#1. It appears you are acknowledging there can be a cause and effect relationship (I called it a correlation). A fuel's octane can affect performance (via timing changes) right? If that's true then how can there be no correlation between octane and timing? Some kind of relationship exists doesn't it?

Question#2. Your answer is no. You can't be sure, and that is the correct answer.

I think at the heart of the disagreement is this notion that there is a correct octane number. Toyota didn't design the engine for a specific octane number, there isn't a certain number that you need. Rather, Toyota designed the engine to use a range of octanes, resulting in a range of engine performance. Toyota doesn't recommend high octane fuel simply to make us waste money and carbon up our cylinders.

 

[Koz]

The energy difference between regular and premium fuel is so minimal it does not matter and has nothing to do with deciding which to use. Octane rating is in no way correlated with engine power or efficiency. You guys can argue all day about it, the fact is that higher octane fuel is NOT a measure of power but of the fuels resistance to ignition from heat. A higher-octane fuel also, under identical combustion chamber conditions, will burn slower.

Koz

 

[Pistonslap]

The energy difference between regular and premium fuel is so minimal it does not matter and has nothing to do with deciding which to use. Octane rating is in no way correlated with engine power or efficiency. You guys can argue all day about it, the fact is that higher octane fuel is NOT a measure of power but of the fuels resistance to ignition from heat. A higher-octane fuel also, under identical combustion chamber conditions, will burn slower.

Koz

Kozman what are you saying? That is a total half tuth and lie. J/K. Thanks for putting in it different words. Maybe the boyscouts will understand now.

 

[RickyCRX]

The energy difference between regular and premium fuel is so minimal it does not matter and has nothing to do with deciding which to use. Octane rating is in no way correlated with engine power or efficiency. You guys can argue all day about it, the fact is that higher octane fuel is NOT a measure of power but of the fuels resistance to ignition from heat. A higher-octane fuel also, under identical combustion chamber conditions, will burn slower.

Koz

Yep, higher octane will burn slower, which helps you run higher compression ratios due to higher cylinder pressures (and temperatures, which tend to preignite lower octane fuels because they burn more quickly).

But again, since the spark plug already fires BEFORE the piston reaches TDC, if you wait until later in the compression stroke to fire the spark plug (retarding the timing), then you will have less of a change of pre-ignition (knocking) happening. However, if you have a compression ratio high enough and can also fire the spark plug sooner, you will have more complete burning but without preignition. There's a delicate balance and there ARE cases where you can feel a noticeable difference.

If you've ever owned a high compression ratio Honda (like an Integra GS-R, Type-R, or Honda S2000), you will KNOW what I'm talking about. These have compression ratios of 10.1:1, 10.6:1, and 11.0:1, respectively. With the 4Runner's compression ratio of 9.5:1 (or 9.6, depending on year), the engine DEFINITELY can benefit from the use of higher octane fuel.

Ricky

 

[RickyCRX]

Oh, and read section 6.13 on this page that I just found while doing a google search:

http://www.repairfaq.org/filipg/AUTO/F_Gasoline6.html

It reiterated exactly what I've been saying. "If you are already using a fuel with an octane rating slightly below the optimum, then using a higher octane fuel will cause the engine management system to move to the optimum settings, possibly resulting in both increased power and improved fuel economy."

In this case, the 4Runner's "optimum" would be 91 octane, according to the owner's manual.

Ricky

 

[Koz]

Kozman what are you saying? That is a total half tuth and lie. J/K. Thanks for putting in it different words. Maybe the boyscouts will understand now.

:wtf:

Koz

 

[Pistonslap]

J/K= Just Kidding. The first part was sarcasm.

 

[Pistonslap]

Oh, and read section 6.13 on this page that I just found while doing a google search:

http://www.repairfaq.org/filipg/AUTO/F_Gasoline6.html

It reiterated exactly what I've been saying. "If you are already using a fuel with an octane rating slightly below the optimum, then using a higher octane fuel will cause the engine management system to move to the optimum settings, possibly resulting in both increased power and improved fuel economy."

In this case, the 4Runner's "optimum" would be 91 octane, according to the owner's manual.

Ricky

Your wild speculation kills me. Please tell me that you are really not that stupid? Were that the case, under normal operating conditions you would see a benefit by using higher octane fuel. I have seen none in my 4 runner. No increase in mileage, no increase in performance. I agree, that is not truely scientific test, but it is good enough for me.

You do understand that your knock sensor is reactive, right? It does not measure the octane running through your fuel system. If it does not detect preignition, it does nothing. I will admit that I don't know how sensitive it is, but I have made mine ping going up hill towing a 3000lbs boat in heavy stop and go traffic on a 90 degree day. On that day, without a doubt, I would have benefited from higher octane fuel.

Please do us all a favor, before you come up with another one of your baseless theories, get some real test data to back it up. I really am tired of your mindless thoughts.

 

[Iowa4Runner]

Kozman what are you saying? That is a total half tuth and lie. J/K. Thanks for putting in it different words. Maybe the boyscouts will understand now.

Less than half of a fuel's chemical energy is converted to mechanical energy in a 4Runner. There's plenty of room for improvement in the energy conversion department, and that's where octane comes into play.

 

[Koz]

Less than half of a fuel's chemical energy is converted to mechanical energy in a 4Runner. There's plenty of room for improvement in the energy conversion department, and that's where octane comes into play.

:wtf:

Koz

 

[RickyCRX]

Your wild speculation kills me. Please tell me that you are really not that stupid? Were that the case, under normal operating conditions you would see a benefit by using higher octane fuel. I have seen none in my 4 runner. No increase in mileage, no increase in performance. I agree, that is not truely scientific test, but it is good enough for me.

As they always say: "Your butt dyno is full of sh!#"

Put your 4Runner on a dyno with a tank of 87 fuel, then drain it and put in a tank of 93 and run it again and let me know what the difference is. You ridicule me for having 'baseless claims'... Well, your perception of power and economy that is 'not truely a scientific test, but it is good enough for me' is NOT good enough for me. Prove it; strap your car to a dyno, then get back with me.

You do understand that your knock sensor is reactive, right? It does not measure the octane running through your fuel system. If it does not detect preignition, it does nothing. I will admit that I don't know how sensitive it is, but I have made mine ping going up hill towing a 3000lbs boat in heavy stop and go traffic on a 90 degree day. On that day, without a doubt, I would have benefited from higher octane fuel.

Oh, please... Please, Mr. Know-It-All, what is the difference between your engine's needs pulling a 3,000lb boat and my engine's needs when my right foot pushes the gas pedal into the floorboard as far as it will go while running up a freeway onramp?? Both of our engines will be developing maximum horsepower; both of which would be benefiting from higher octane based on the scenario you described.

If you also read the link I provided, you will notice that it mentioned to try different octanes depending on time of year (winter vs. summer); temperatures do have a lot to do with what your vehicle needs. I run 87 octane in my 4Runner, but I know that it would provide me with more power if I ran premium through it in the summer here in South Central Texas. Until you put a vehicle on a dyno, perceptions are just that; perceptions. Some people don't notice things and others are very sensitive to changes in their vehicle's performance. You may just be somebody who doesn't notice certain things.

Please do us all a favor, before you come up with another one of your baseless theories, get some real test data to back it up. I really am tired of your mindless thoughts.

Those in glass houses.......

Ricky

 

[Iowa4Runner]

:wtf:

Koz

This is a painfully simple concept. What's the problem?

 

[DaveS]

:soapbox:

 

[rossmon1]

Towing my boat at 87octane

Hi All

I just got back from a weekend of fun / sun and it was hot. 95-98f
yesterday as i towed about 3k lbs in a very mountainous terrain.
I have towed the same package with 2 6 cyl jeeps, a 99 dodge ram w/v8, and my early bronco which had a 302.
The toyota motor is much more powerful and smooth than any of those vehicles.(you'll never see that comparo in motor trend!)
I never had a hint of preignition, or any lack of power for the task at hand, even when running the a/c. So, I don't see any need to pay more for gas.

 

[Koz]

This is a painfully simple concept. What's the problem?

Since the engineers at Toyota have missed this "Simple Concept" maybe you could enlighten us.

Koz

 

[Boaz]

:corn: Heheheeheh

 

[Iowa4Runner]

Since the engineers at Toyota have missed this "Simple Concept" maybe you could enlighten us.

Koz

What are you talking about? How did the engineers at Toyota miss this concept? I'm not suggesting Toyota missed anything.

We need to back up and address why you made a point of saying "The energy difference between regular and premium fuel is minimal."

I know this, and have never said or even implied otherwise. I think Ricky knows this too.

What's the significance is of this fact, what's your point?

 

[Koz]

Less than half of a fuel's chemical energy is converted to mechanical energy in a 4Runner. There's plenty of room for improvement in the energy conversion department, and that's where octane comes into play.

Iowa4Runner,

You did make this statement? What does it mean?

Koz

 

[charlier180]

The main thing I try to do is just vary where I buy my gas from - I try not to fill up with the same brand time after time (somebody suggested sticking with the same brand can create a build up of additives - not sure whether that is true but it costs me nothing to vary where I buy from anyway).

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.