85 unleaded..... (1 Viewer)

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WSOPgold2012

MoxieMan
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Givin it a go as its .25c/g cheaper than 87. Hopin itll run smooth with the EFI conversion. So far so good...at idle!! #FingersCrossed

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You should run the lowest octane fuel you can that doesn’t cause pinging/detonation.
 
At 10* initial my truck will audibly knock above 2500rpm on 87. I have to run 89-93.

It likes the non ethanol 93 the best.
 
Carefully calculate your true mpg with a calibrated odometer with that fuel. You'll likely find the MPG hit won't make up the few pennies saved. At sea level,, 87 octane fuel is garbage in the 2F and the most expensive fuel you can buy due to the decrease in mpg. And you're using 85. But that's with a carb. Maybe your EFI can work magic.
 
Ran smooth as buttah....for 25 miles 🤣🤣😊😂😉😉
 
Carefully calculate your true mpg with a calibrated odometer with that fuel. You'll likely find the MPG hit won't make up the few pennies saved. At sea level,, 87 octane fuel is garbage in the 2F and the most expensive fuel you can buy due to the decrease in mpg. And you're using 85. But that's with a carb. Maybe your EFI can work magic.
Def will keep this in mind....Saving $4/fill up would be spiffy tho.
 
You should run the lowest octane fuel you can that doesn’t cause pinging/detonation.
Why im trying 85 again. Didnt like it while carburated at 10000'....but ran like a champ from 5000' to 7700' today. #FingersCrossed
 
85 is typically sold in higher elevation areas where your compression is inherently lower, and thus, your need for octane points is lower.
 
Carefully calculate your true mpg with a calibrated odometer with that fuel. You'll likely find the MPG hit won't make up the few pennies saved. At sea level,, 87 octane fuel is garbage in the 2F and the most expensive fuel you can buy due to the decrease in mpg. And you're using 85. But that's with a carb. Maybe your EFI can work magic.

I've run 87, 89, and 93 octane fuel in my truck and calculated the mileages for multiple tanks of fuel and not seen an appreciable difference in mileage. Mostly i run the higher octane now and then as I have desmogged and my dizzy curve is still set for the emmissions.

Math wise if I use from the AAA website:

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There is a 27.5 cent difference per gallon between regular and mid grade. In a full 25 gallon fill up thats a $6.87 difference in cost from regular to mid grade. So I can buy 2.5 more gallons of regular for the same price of Mid-Grade. If I'm basing my decision on mileage then I better be getting an increase in mileage that offsets this 2.5 gallon buffer. In my case my mileage always varies between 13.3 and about 14 mpg regardless of whether I filled up with 93 or 87. If I can get 13mpg with 87 octane then I need to to get at least 14.3 mpg to equal the cost difference from regular to mid grade.

All this said there is no mechanism in the 2F engine that is capable of optimizing for higher octane fuel. There is no system measuring knock and adjusting the ignition to maximize advance like on a modern system. Also the higher octane fuel will produce less power for a low compression engine like the 2F. The only thing the higher octane will do is bandaid the preignition/detonation issues like I have because of my ignition advance curve or because carbon buildup etc.


Now in my 1999 Saab 9-5 I always run 93 octane fuel when I can get it because it is high compression engine and also turbocharged running a reasonable amount of boost. With the higher octane fuel the computer can maximize the timing and boost and get more torque out of the engine which in turn allows me to run a lower gear with less rpms and use less fuel. If I run 87 in this car I can feel the power the difference and the car drives much worse. I also see a significant drop in mpg because I can no longer run the boost.
 
Where is this that the gas has such low octane?
 
Where is this that the gas has such low octane?
Colorado as stated...but i see it all over Midwest...Kansas,Misiouri, Iowa, Wyoming ect ect
 
Most mountainous area either have 85 or 86. Premium is usually 90 or 91. I guess its proportional to the amount of oxygen available. Higher elevations is less O2 so reduced horsepower. Less need for the higher octane numbers, within reason.
 
My desmogged 1987 pings terribly on 87, usually on the highway. I switched to 93, and all is my 2F world. My truck has been properly desmogged, so I assume that I have a good amount of carbon buildup somewhere......
 
I've run 87, 89, and 93 octane fuel in my truck and calculated the mileages for multiple tanks of fuel and not seen an appreciable difference in mileage. Mostly i run the higher octane now and then as I have desmogged and my dizzy curve is still set for the emmissions.

Math wise if I use from the AAA website:

View attachment 2184698

There is a 27.5 cent difference per gallon between regular and mid grade. In a full 25 gallon fill up thats a $6.87 difference in cost from regular to mid grade. So I can buy 2.5 more gallons of regular for the same price of Mid-Grade. If I'm basing my decision on mileage then I better be getting an increase in mileage that offsets this 2.5 gallon buffer. In my case my mileage always varies between 13.3 and about 14 mpg regardless of whether I filled up with 93 or 87. If I can get 13mpg with 87 octane then I need to to get at least 14.3 mpg to equal the cost difference from regular to mid grade.

All this said there is no mechanism in the 2F engine that is capable of optimizing for higher octane fuel. There is no system measuring knock and adjusting the ignition to maximize advance like on a modern system. Also the higher octane fuel will produce less power for a low compression engine like the 2F. The only thing the higher octane will do is bandaid the preignition/detonation issues like I have because of my ignition advance curve or because carbon buildup etc.


Now in my 1999 Saab 9-5 I always run 93 octane fuel when I can get it because it is high compression engine and also turbocharged running a reasonable amount of boost. With the higher octane fuel the computer can maximize the timing and boost and get more torque out of the engine which in turn allows me to run a lower gear with less rpms and use less fuel. If I run 87 in this car I can feel the power the difference and the car drives much worse. I also see a significant drop in mpg because I can no longer run the boost.
Had to read this 3 times...but, i think this is good news for me lololol. Ty
 
My desmogged 1987 pings terribly on 87, usually on the highway. I switched to 93, and all is my 2F world. My truck has been properly desmogged, so I assume that I have a good amount of carbon buildup somewhere......
93 in a 2F? Something ain't right. I guess it could be carbon, but that still doesn't sound right to me. In these low compression tractor motors, you should not have to use premium. It definitely isn't called out by Toyota.
 

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