Pretty good MPG in the mountains

Idk about this E88 fuel, but all our grades here are E10. I never noticed any change in fuel economy when i ran E87 in my tundra, and when on trips up north switched to the non ethanol 87 offered. My tacoma runs fine on E10 87 fuel.

 

Ethanol contains about 30% less chemical energy density than gasoline, so E85 fuel would be somewhere north of 20% less efficient as far as energy released during combustion assuming the engine is not designed to run it and the ECU doesn't compensate by injecting more fuel.

 

Where does it clearly say not to? It says not to use E85

 

Literally reads "Up to E15" right on the cap. Regardless, as the post above you states, fuel containing more ethanol uses more energy so you will get worse gas mileage.

I am going to guess that you changed the display measurements to show MPG Imperial instead of MPG US.

 

Actually they did a test on myth busters sometime back that these newer vehicles with all the sensors and ecu were able to run on pure ethanol just fine. It was the older carb engines that wouldn't without major jetting changes.

 

I have to check that out, did they get the same/better/worse mileage?

 

I'd bet money he means normal 88 octane with ethanol, not actual ethanol fuel. For relatively slow speeds with a lot of downhills that is totally believable fuel economy.

I just did a trip with my truck loaded with hunting gear, a topper, supercharged, 33's and went over several 10k foot passes, did 75mph on the freeway and averaged 19.6mpg.

 

Run fine or not, they won't make as much power and therefor efficiency will go down significantly. The O2 sensor(s) and CL feedback will account for excess oxygen and richen the mixture until it is happy IF the ECU has the authority and the injectors have the capacity, still being down on power compared to gas. In OL behavior the engine will be very lean, the STFT will reach its limit and power will be way down.

I'd be interested to watch that episode. MB does some interesting stuff but they usually perform a poor test setup without a control and the results are less than reliable.

I don't know why I didn't think of this. makes sense

 

That they didn't report. They only proved these newer vehicles could run fine just on on moonshine. When they tried it in an older car that had a carburetor it just began to run... farted, and stalled out.

 

You guessed wrong.

Good catch. You're correct. I'll update the post.

 

I've always gotten better fuel mileage in mountains, I don't think the 88 octane was the difference. You burn more fuel going up but being able to coast down the other side more than makes up for it. It is wind resistance at speeds over 70 mph on level ground that eats up the most fuel. I can match the fuel mileage I get in mountains if I keep speeds under 50-60 mph on level ground. But who does that?

I've done a lot of research, and experimenting in the last year, especially since July on octane ratings and what is best to use in my vehicles. Based on what I've found; if your vehicle is less than about 20 years old you shouldn't be running 85 octane fuel even in the mountains. In fact they probably shouldn't even offer it anymore.

Years ago if your vehicle was designed to use premium 93 octane fuel it would run like cap on 87 and in fact long term use of 87 could cause damage. And if your vehicle was designed for 87 octane it was a waste of money to buy 89 or 93 octane. And at altitude 85 octane was even OK.

But all newer vehicles (around 15 years old or newer) are designed to give best performance with 93 octane fuel. And with computers controlling everything now the engine can compensate for 87 octane and still give acceptable performance without doing any damage. But never 85 octane, even at altitude.

Using the higher octane fuel is most noticeable when towing, but you'll get a little better performance all the time. You might get a little better fuel mileage, but probably not enough to offset the added costs. And the newer the vehicle, the more likely 93 octane fuel is to make a difference. A 3rd gen should benefit more from it than my 2nd gen.

I've decided to run 93 octane in my vehicles. Doing the math at todays fuel prices, it will cost me about $200 to drive 1000 miles on 93 octane vs $170 on 87 octane even if fuel mileage remains the same. If I can get one more MPG by using 93 octane then the additional cost is even less. To me the $20-$30 more every 1000 miles is worth it. For you it may not. Your truck should still run OK. But if you want more power give the premium gas a try.

 

I think l remember that episode, they were running a modern V6 Camaro around a circle track IIRC.

 

Myth busters was entertainment and put that ahead of actual scientific method. Even when challenged on results they’d repeat the same errors. Some things don’t scale up from the models used and others used bad assumptions with huge error margins and the crash test dummy paid the price. Fun show though as long as you didn’t take it for real.

 

S

Sure, the show is entertainment, but for the most part it is real....many episodes have been back up by scientific fact.

 

Just sayin you can’t take that as given without that backup. Using them alone as “proof” of anything is not justified. The concepts are real enough but the devil is always in the details where “close enough” doesn’t cut it. I would never take their “proven” or “busted” as anything meaningful without closer examination. I enjoyed the show in spite of that not because I believed them inherently. 60 minutes is another show that pretends to be fact based but also places drama/entertainment value ahead of reality. It’s not that they don’t have value but that journalistic integrity is not of primary importance.