Which grade of unleaded do you prefer? Have you seen a difference between grades in either mileage and/or performance?
Fuel Type? (1 Viewer)
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Factory manual suggests no less than 87 octane. Being a poor college student 
, I uses what I can affords.
, I uses what I can affords.
Pretty much anything short of water.
I'm serious. The 3FE was built to handle the crap they call gas in Africa. But I would recommend pump gas.
I put mid-grade in mine. It's funny to see the looks on people's faces when they see a 20-year-old hand the cashier $70 every week.
Factory manual suggests no less than 87 octane. Being a poor college student
I'm a poor college student, too....oh wait....I still live at home.
My suggestion and what I do is to run each grade of gas through several tanks and check mileages. The tank that you get the highest mileage out of is almost always the most efficient. For example, if 91 Octane is the most efficient you'll usually break even compared to saving money and getting poor gas mileage. The only thing to look out for is "pinging" this means that your timing and octane aren't matching up and you are damaging your motor. The dumbed down version, if you wanted to know, the lower the octane the faster the burn. So, if your motor is timed for a lower octane, read fast burn, and you run a higher octane, your exhaust valves are opening with less of a burn, read inefficient. Rant off!
Not to be the party pooper here, but everything I've ever read or heard on the subject is that there are absolutely no performance or gas mileage gains from running higher octane gas through an engine built for 87. In fact, it can actually be worse for the engine. High octane gas is not cleaner or better in any way. The idea that the occasional tank of premium will clean the engine is a common misconception. The octane rating refers to something about the speed at which the gas ignites. If your engine is designed for 87 (like the 80 series) and you put higher octane in it, then the fuel burns at a different rate which means that your timing will be off. You're paying extra money for no purpose and could be harming the engine.
bpenn1980
SILVER Star
Curious about this one myself. Prior owner said she only ran premium for 13 years, so that is what I've been running the last couple months. Since it had the premium stuff for so long I'm kind of scared to switch things up on the truck!
Think I should try dropping down to mid-grade and see how she runs?
Think I should try dropping down to mid-grade and see how she runs?
Wow...this is an eye opener. So no high octane fuel? Doesn't the manual say no less than 87? that means we can put 89 or 91 right?
I'm not sure if you're a mechanic/rocket scientist, or what, but I'm going to go out on a limb and say that I believe part of your octane theory is incorrect.
The higher the octane, the more pressure it takes for it to ignite. Meaning an engine with a high compression ratio (mostly sports cars, exotitcs, etc.) would need to use high octane gasoline.
The pressure would cause 87 octane to ignite before the spark plug ignited it, and would cause the engine to knock or ping.
Basically, as long as the spark plug is igniting the gasoline, it isn't going to harm the engine. I think putting some of the stuff you'll find at race tracks, like 97 octane and whatever, may cause harm, but using 91 shouldn't harm anything. Unless you happen to be driving an Indy car.
But you're not, you're driving a Land Cruiser, otherwise you wouldn't be here.
I need to go to bed.
Pretty much anything short of water.
I'm serious. The 3FE was built to handle the crap they call gas in Africa. But I would recommend pump gas.
I put mid-grade in mine. It's funny to see the looks on people's faces when they see a 20-year-old hand the cashier $70 every week.
That's why I use my ATM card when I do it twice a week.
I use 91. I can tell the Cruiser likes it better. Trust me.
These are very low compression engines fellas... Low compression, no supercharger, and factory set timing = 87 octane. Anything else is a waste IMO.
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I use 85 octane
From Wikipedia:
"The power output of an engine depends on the energy content of its fuel, and this bears no simple relationship to the octane rating. A common understanding that may apply in only limited circumstances amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this may be false under most conditions — while engines perform best when using fuel with the octane rating for which they were designed and any increase in performance by using a fuel with a different octane rating is minimal or even imaginary, unless there are carbon hotspots, fuel injector clogging or other conditions that may cause a lean situation that can cause knocking that are more common in high mileage vehicles, which would cause modern cars to retard timing thus leading to a loss of both responsiveness and fuel economy. This also does not apply to turbocharged vehicles, which may be allowed to run greater advance in certain circumstances due to external temperatures."
"The power output of an engine depends on the energy content of its fuel, and this bears no simple relationship to the octane rating. A common understanding that may apply in only limited circumstances amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this may be false under most conditions — while engines perform best when using fuel with the octane rating for which they were designed and any increase in performance by using a fuel with a different octane rating is minimal or even imaginary, unless there are carbon hotspots, fuel injector clogging or other conditions that may cause a lean situation that can cause knocking that are more common in high mileage vehicles, which would cause modern cars to retard timing thus leading to a loss of both responsiveness and fuel economy. This also does not apply to turbocharged vehicles, which may be allowed to run greater advance in certain circumstances due to external temperatures."
invest in getting injectors professionally cleaned and doing a seafoam treatment, will more than make up for the expense of running 91 or higher.
Also higher octane fuel does take "longer" to burn. Hence why in motorsports we pick which fuel we can use and build almost everything around that...and then can do the final tuning based on fuel mixture. Hence why we carry hydrometers with us and mix fuel at the track.
Static Compression in itself does not have a bearing on fuel needed. My daily driver is a 12:1 motor that runs on 87 octane. Ignition timing, camshaft timing/dynamic compression, and combustion dynamics, spark plug temps, running temperature...etc determine needed octane.
The PCP(peak cylinder pressure) needs to occur at 13* atdc for most efficient work to be exerted on the angle of the crank. So the motor is designed and ignition timing set so that with the desired fuel it burns and PCP occurs at 13 atdc. If 91 or 93 octane makes your car run better, I would assume your ignition or chambers need cleaned up or maintenance as 93 octane would naturally cause PCP to be delayed and thus loose torque and power.
I hope this makes some sense.
Also higher octane fuel does take "longer" to burn. Hence why in motorsports we pick which fuel we can use and build almost everything around that...and then can do the final tuning based on fuel mixture. Hence why we carry hydrometers with us and mix fuel at the track.
Static Compression in itself does not have a bearing on fuel needed. My daily driver is a 12:1 motor that runs on 87 octane. Ignition timing, camshaft timing/dynamic compression, and combustion dynamics, spark plug temps, running temperature...etc determine needed octane.
The PCP(peak cylinder pressure) needs to occur at 13* atdc for most efficient work to be exerted on the angle of the crank. So the motor is designed and ignition timing set so that with the desired fuel it burns and PCP occurs at 13 atdc. If 91 or 93 octane makes your car run better, I would assume your ignition or chambers need cleaned up or maintenance as 93 octane would naturally cause PCP to be delayed and thus loose torque and power.
I hope this makes some sense.
Mine will knock with 87. Dunno why. But I don't like hearing it. So I use 89.
I use 87 octane 99% of the time and use whatever brand is cheapest. No problems 99% of the time. Rarely, usually when traveling, I will get a tad of pinging after a fill-up, most likely due to crap gas. I also will occasionally, just for grins, put in 93 octane; and the vehicle does have a tad more power, better acceleration etc while that fuel is in the tank.
Grench
SILVER Star
I run the 10% Ethanol blend. 90-91 Octane. But not for the Octane value.
Ethyl alcohol has about 90% of the energy per gallon as the 87 no lead that it gets mixed with.
Here, Ethanol 91 Octane is $0.20 a gallon cheaper than 87 no lead.
So... ~99% of the energy, 94% of the cost per gallon ~ 5% cheaper per mile. It has nothing to do with the Octane though.
Since we in the US are securely shielded from any real information about the gas we buy, I buy whats cheap. It all comes from the same truck/storage facility/pipeline/hole in the ground.
YMMV
Ethyl alcohol has about 90% of the energy per gallon as the 87 no lead that it gets mixed with.
Here, Ethanol 91 Octane is $0.20 a gallon cheaper than 87 no lead.
So... ~99% of the energy, 94% of the cost per gallon ~ 5% cheaper per mile. It has nothing to do with the Octane though.
Since we in the US are securely shielded from any real information about the gas we buy, I buy whats cheap. It all comes from the same truck/storage facility/pipeline/hole in the ground.
YMMV
Sometimes I run 100 octane in my 3fe and I run 12.4 second quarter miles...
