Gas prices/Octane rating required?
- Thread starter SWUtah
- Start date
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I work in the industry, so I thought I would bring my change to the table. I will do my best at laymans.
Octane = Resistance to burn rating. Not the density of oxygen. Higher compression engines need higher octane so they don't pre-ignite the fuel before the piston has reached the peak of it's travel.
Volatility = 1 cup of fuel should make 20 cups of vapor at a given temperature for proper mixture. (speaking only for gasoline) This is why we have winter and summer blend fuels because of temperature differences. So you have to make a fuel that will be volatile at 20 degrees F, and then make a fuel that will be volatile at 100 degrees F. The engine would not run right at all if you tried to run the same time of fuel year round. Think of it like a broken clock, it is only right twice a day.
Whether or not you can run different octane fuels in your landcruiser than what is specified. YES, yes you can.
Will you experience the same level of performance that the engineers planned for, NO, no you won't.
Will you damage anything in the engine bay, NO, no you won't.
Engines capable of monitoring "PING" will introduce more fuel (like all you boys with FI engines) to compesate. Once this compensation has happened your fuel/air ratio is set. You will burn a slight percentage more fuel per cycle than an engine that was designed to run on lower octane. Performance will be lacking slightly. This is something like being tone deaf. Some people will notice this loss of power, and others won't.
Now, there is a wicked idea that I must make you aware of. Particularly on engines spec'd to run 87 and you try and run 93 octane. In this situation you CAN cause premature failure of components due to excess un-burned fuel leaving the combustion chamber and causing the carbon to adhere to engine components. When your engine does not reach high compression it does not need high octane fuel, therefore using these fuels will NOT boost performance. The excess unburned fuel is just ejected out of the cylinder in a vapor form and as it cools it will adhere carbon deposits in and around the exhaust.
The catalytic converter prevents this stuff from being ejected out the tail pipe and your O2 sensor will help a little with leaning you out some, but there is no way the engine can change timing for this condition. When running low octane in a high octane engine, it can retard the timing a little.
Now I don't know if I helped this argument any...I tend to suck at breaking this stuff down in easy to read segments. Mostly I just dork out and glaze peoples eyes over.
My background is I manage Chemicals and Lubricants for a major engine builder. I am certified in two engine lines (not Toyota) as a technician and just love to tinker on anything new.
Octane = Resistance to burn rating. Not the density of oxygen. Higher compression engines need higher octane so they don't pre-ignite the fuel before the piston has reached the peak of it's travel.
Volatility = 1 cup of fuel should make 20 cups of vapor at a given temperature for proper mixture. (speaking only for gasoline) This is why we have winter and summer blend fuels because of temperature differences. So you have to make a fuel that will be volatile at 20 degrees F, and then make a fuel that will be volatile at 100 degrees F. The engine would not run right at all if you tried to run the same time of fuel year round. Think of it like a broken clock, it is only right twice a day.
Whether or not you can run different octane fuels in your landcruiser than what is specified. YES, yes you can.
Will you experience the same level of performance that the engineers planned for, NO, no you won't.
Will you damage anything in the engine bay, NO, no you won't.
Engines capable of monitoring "PING" will introduce more fuel (like all you boys with FI engines) to compesate. Once this compensation has happened your fuel/air ratio is set. You will burn a slight percentage more fuel per cycle than an engine that was designed to run on lower octane. Performance will be lacking slightly. This is something like being tone deaf. Some people will notice this loss of power, and others won't.
Now, there is a wicked idea that I must make you aware of. Particularly on engines spec'd to run 87 and you try and run 93 octane. In this situation you CAN cause premature failure of components due to excess un-burned fuel leaving the combustion chamber and causing the carbon to adhere to engine components. When your engine does not reach high compression it does not need high octane fuel, therefore using these fuels will NOT boost performance. The excess unburned fuel is just ejected out of the cylinder in a vapor form and as it cools it will adhere carbon deposits in and around the exhaust.
The catalytic converter prevents this stuff from being ejected out the tail pipe and your O2 sensor will help a little with leaning you out some, but there is no way the engine can change timing for this condition. When running low octane in a high octane engine, it can retard the timing a little.
Now I don't know if I helped this argument any...I tend to suck at breaking this stuff down in easy to read segments. Mostly I just dork out and glaze peoples eyes over.
My background is I manage Chemicals and Lubricants for a major engine builder. I am certified in two engine lines (not Toyota) as a technician and just love to tinker on anything new.
Pskhaat
Tourer
Hey Proven, I don't actually work in the industry but went to a particular boutique Uni that is geared towards raping the land 
and thus produced it's wealth of mining & petroleum engineers, as such I had the `blessings' as a Mathematics major of the requirement for way too many petro/mining courses way back.
Though I'm kind of with you on this, can it not also be argued that the different blends have much to do with perceived (and possibly correct) environmental impacts by season, as well as seasonal availability of blends like ethanol. The Front Range has drastically different atmospheric conditions in summer and winter and fuel to my understading is blended accordingly. In counter to this, there are many locales in AZ that in summer >115F that get fuel from coastal CA blends where temperatures are drastically more mild where that doesn't seem to make sense.
Even modern EFI systems still don't handle extreme conditions well. When it's absurdly hot in PHX, low-test gasoline will make many well maintained 80 series' LCs pre-ignite on low RPM high load cases. I've also heard cases of overly-rich smells from 100s in extreme cold conditions.
Couldn't agree with you more on this! Let me ask you this as I have no idea but the theory is in this case like on our Hundys though they're spec'd for high-test to run a tank every once in a while of low-test and introduce more complete burn to help the chamber and cats. True?
and thus produced it's wealth of mining & petroleum engineers, as such I had the `blessings' as a Mathematics major of the requirement for way too many petro/mining courses way back.Though I'm kind of with you on this, can it not also be argued that the different blends have much to do with perceived (and possibly correct) environmental impacts by season, as well as seasonal availability of blends like ethanol. The Front Range has drastically different atmospheric conditions in summer and winter and fuel to my understading is blended accordingly. In counter to this, there are many locales in AZ that in summer >115F that get fuel from coastal CA blends where temperatures are drastically more mild where that doesn't seem to make sense.
Even modern EFI systems still don't handle extreme conditions well. When it's absurdly hot in PHX, low-test gasoline will make many well maintained 80 series' LCs pre-ignite on low RPM high load cases. I've also heard cases of overly-rich smells from 100s in extreme cold conditions.
Couldn't agree with you more on this! Let me ask you this as I have no idea but the theory is in this case like on our Hundys though they're spec'd for high-test to run a tank every once in a while of low-test and introduce more complete burn to help the chamber and cats. True?
[/QUOTE]
This is a new one. While I won't say this is wrong it is a very unique idea. I can't think of a reason I would do this as a "Maintenance" item. Might bounce this around some other brains and get some feedback.
Yes, there is regions where they must do this for environmental issues as well. I was going for a more broad explaination hitting a majority, rather than a minority. Seasonality can also mean "Higher Smog levels." With the number of new blends across the united states it is hard (no, near impossible) to keep up with them. MTBE being replaced with Ethanol as high as 10% in some regions of the US has played some forms of havoc on engine performance across the board. Ethanol being a way of modifying octane level, as well as assisting with smog levels, does not burn as well as some other additives.....wait...I am rambling.
In short, each region has fuels that are spec'd for a number of reasons. Not just the season/temp, but the reason for the seasonal fuel is based on volatility. Everything else is a tweak to the additives packages.
______
If you would like to experiment with this. Take a gallon of fuel purchased at the end of summer, and store it through fall with fuel stabilizer. Try and run that fuel in your garden equipment and you might see what I am trying to demonstrate. Fuel stabilizer is good for about 3 to 6 months of fuel storage.
Pskhaat said:
This is a new one. While I won't say this is wrong it is a very unique idea. I can't think of a reason I would do this as a "Maintenance" item. Might bounce this around some other brains and get some feedback.
Yes, there is regions where they must do this for environmental issues as well. I was going for a more broad explaination hitting a majority, rather than a minority. Seasonality can also mean "Higher Smog levels." With the number of new blends across the united states it is hard (no, near impossible) to keep up with them. MTBE being replaced with Ethanol as high as 10% in some regions of the US has played some forms of havoc on engine performance across the board. Ethanol being a way of modifying octane level, as well as assisting with smog levels, does not burn as well as some other additives.....wait...I am rambling.
In short, each region has fuels that are spec'd for a number of reasons. Not just the season/temp, but the reason for the seasonal fuel is based on volatility. Everything else is a tweak to the additives packages.
______
If you would like to experiment with this. Take a gallon of fuel purchased at the end of summer, and store it through fall with fuel stabilizer. Try and run that fuel in your garden equipment and you might see what I am trying to demonstrate. Fuel stabilizer is good for about 3 to 6 months of fuel storage.
- Thread starter
- #25
Wow, very great post and information. Thanks
I think I will continue with my use of 91 octane in my 99 since regular here is 85 octane and I live at 5000 ft. and drive up and down several KKK ft. on a regular basis.
I think I will continue with my use of 91 octane in my 99 since regular here is 85 octane and I live at 5000 ft. and drive up and down several KKK ft. on a regular basis.
