14mpg on 94 octane?

Why is that? Way back in the day I used low lead avgas when I raced. Obviously the motors back then were nothing like what we have our modern Tacomas.

 

You could get away with it years ago on a car with a carb. Avgas has a different Vapor Pressure and will not run right in your truck, I would not use it.

 

Can you tell us the exact steps you are using to calculate your mpg?

 

If I'm understanding this correctly avgas is leaded (adding lead stabilizes lower quality gasoline, basically bumps it up to a higher octane rating so that it can withstand higher compression) and can clog up catalytic converters rather quickly.

 

Thanks

 

At this gas fill up:
-Do NOT top off tank; let it shut off automatically and leave it.
-Reset trip odometer to 0 before actually starting truck
-Check tire pressure to confirm full and even pressure

At the next fill up:
-Check mileage on trip odometer; record this mileage
-Fill as before, not topping off tank. Record exact number of gallons pumped
-Divide the number of miles driven by the number of gallons of gas pumped
-The result is your MPG for the previous tank of gas.


Do this a few times, and try to fill up your tank the same time every day to avoid the temperature affecting the amount of gas you actually get. When you average this over about a month period, you'll get a decent picture of your average MPG.

 

You need to run race fuel in your truck to get better milage.either that or read up on how fuel works with your engine rather then assuming high octane fuel gives you better milage.

Or you could break into a airport and steal some jet fuel

 

I will agree with that but it is no greater than 3% Ethanol has heat value it burns pretty good and has an octane rating close to 110 there is less energy pound for pound but it is not useless as a fuel. So in the summer I get around 400 miles out of a tank but because I use a 10% mix it costs me about 12 miles of driving I don't think I'll lose any sleep.

 

Don't let the Harley guys know that they will drive 50 miles to waste their money. Even if av gas made a difference it would have to be substantial to make it worth $4.49 a gallon that’s twice what 87 goes for and there is not a shot of getting 40 MPG or having twice the power. Piston air craft at this point still use lead in the fuel because of it’s anti knock properties (not good for “cats”, or dogs for that matter) it is fairly low level but engine knock in an aircraft can be fatal not so much in a vehicle. Lead way back in time was also used in iron heads to lub valve seats but hard valve seat inserts in alloy heads eliminated that problem. Ethanol is not used because it’s hydroscopic and even on a warm summer day an aircraft engine is prone to carb icing. That also has a tendency to make air planes not fly any more. No I would not advocate using av fuel in any thing other that what it was intended for, that was my point of the joke.

 

I do this. I also try to fill up at the exact same pump as much as possible. I know that each fill up is not an exactly accurate measure of MPG, but the trend is what's important. I don't care if I get 17.5 or 18 (or 15 when the driving conditions cause it), I'm just keeping track in case there's a sudden change for apparently no reason.

 

Every time I go to Mexico, my mileage jumps up, and I am heavily loaded on those trips. Back here, with an empty truck, my mileage drops again. Consistently proves adding corn to gasoline dilutes true engine fuel with chicken/ cow/ human fuel!

 

Disagree with some of your opinions.
First make sure of your data. Use GPS or mile markers to determine how much error on your odometer/trip meter. Zero a trip meter and use gps or mile markers to confirm. If you drive 50 miles and trip shows 49 or 51 you have a 2% error - 49 it reads "low", 51 it reads high. When you do calculate mpg, adjust your total miles accordingly. Speedometer and odometer can have different error %, and both will change as tires wear.

Tire Pressure - Always measure before driving, and before sunlight has heated up the tires. Do it at home, write it down by tire. Get to air pump, measure again. If tire was 28 at home, and should be 30, and is 31 at the air pump, you still add 2 pounds.

Same time of day when filling up has NO effect on the amount of gas you pump. Gas station tank is underground, temperature is constant, so it doesn't matter what time of day you fill it.

Hardest thing to get accurate is how full your tank is on fillup. If you don't want to fill it to the top, take an average over several fillups of similar driving (averaging 1 tank all city vs 1 tank highway does not help here).

 

Something else is going on there other then ethanol.

Its true that ethanol only has 2/3 the energy of gasoline. 76K BTU/gallon versus 114K BTU/gallon. But that's only 1/3 less energy in 10% of the E10 blend. You get 97% to 98% (depending on which published data is used) of the power and mileage when burning E10. Around here the price premium for non-ethanol gasoline is quite a bit more than 2 or 3 percent so it costs more per mile to drive with the"good stuff". I suspect that is the case everywhere in the US.

I still use non-ethanol fuel in my boat and yard equipment. But it doesn't do anything other than waste money to use it in our trucks.

 

I tried 2 tanks of 91 octane on a trip last year, got 21.5 mpg on the trip out (across the Cascade Mountains). Filled up with 89 starting the trip back. 21.7 mpg on the way back. The difference is probably the route we took, Highway 2 on the way out and highway 20 coming back. Couldn't go as fast coming back. I drove on the way out, my brother on the way back so we have similar driving styles. 91 octane is a waste of money, the truck doesn't need it.

 

Aviation gas is called 100LL, the LL means low lead. It will poison you catalytic converter.

 

That's going to hurt you. Another thing that can kill MPG is unsprung weight. If you put heavier wheels/tires on your truck it will make a difference in your mpg. Example... my stock tires weigh about 36 pounds: 265/65/17 Bridgestone Dueler. The tires you said you have on 265/70/17 K/O's weigh 44 lbs. That's 8 pounds of unsprung weight per corner, 16 per axle. If you've put heavier rims on as well... I'm not surprised your mpg sucks.

 

Higher octane will not give you better gas mileage. It will give better performance on a high compression motor, but not necessary on the 4.0
Lower octane like 87 or 89 will get you better mileage.

 

The unsprung weight affecting fuel economy has a lot to do with driving style. My Taco weighs over 5500 pounds. On each corner I have a 59 pound tire. Most tanks are around 18 MPG. When I tow my camper very far, I'm around 15 MPG. Driving Montana's mountainous highways without the trailer, I'm around 16.5. I have the 6 speed and I don't take off fast.

Post edited for more accurate vehicle weight

 

Like posted above, I also have compared 91 to 87 octane gas and almost no change in mpg. What little difference there was had 87 octane giving better mpg!

As for non-ethanol Mexican gas, yes it was only slightly better, like 1-2 mpg better. However, when you only get 15-18, 17-20 is a big deal!

 

The 6 speed helps, and so does not taking off fast. I also suspect your gas in Montana is better than the oxygenated ethanol crap we get in CA.