Gas Octane

7 years w/ the truck. Tested them all for a time, I run 89. Worth the .10 a gallon. 87 pings low rpm (where best mpg is) and up hills in my 05. Towing 93.

 

Even though you can get 105 AKI fuel in Colorado, as noted it's E85 and you won't ever see as much power or economy since ethanol (85% ethanol = E85) has less energy per unit volume.



Interesting...[/QUOTE]

I'm not sure about that? I have seen two friends cars on the dyno, both turbo Hondas neither did anything but retune to run on e85 and both cars made substantially more power on e85 than the "race" fuel they where running.

 

yes you are correct. all modern day engines only require 87 octane. efi took care of that.

really, thanks ethonal. now my efi driven motor runs like crap!

 

87 octane chevron gas is the best gas to run in a stock engine. no holds barred.
i can prove it, just don't know how to post a link?

 

Used 91 E0 for last 2 weeks and saw 3 mpg improvment, from 15 - 18. Didnt drive enough to save money and gas is like $5.20 in Canada. Im doing long commutes next week and from Jan-Feb so i will see if i actually save money.

 

I have always run 91 or 93 since I first got my taco. Like others have said I have run lower octanes before. but the 1GR does seem to respond and run better on the higher octane.

 

I do 91 every once in a while. I notice a small difference but not significant enough to do it every fill up. I want to try 93 but I dont even think we have that where I live. (maybe its not in cali at all?)

 

Ethanol does not have as much unit energy as does gasoline, that's just the way it is.

It does, however, have other properties, like high octane. Also, it evaporates much faster so it cools the combustion chamber and air/fuel charge better. That would give a tuner some things to exploit: very high compression ratio from elevated turbo boost setting as well as aggressive ignition and valve timing, for instance. It's that which gives the engine greater power, not the fuel's energy.

This is the exact same principle behind top-fuel dragsters burning nitro-methane generating massively more horsepower than gassers. Their huge blowers are packing in incredible amounts of air and fuel on every intake stroke. So much that if they used gasoline the engine would blow up just by the super-charger's compression heating of the air/fuel from pre-ignition. They sometimes do anyway, even though nitro-methane has far less energy per unit volume than ethanol.

 

never tried anyother tane but 91!!!!!!!!.​

 

haha I fill with 91, I think the engine is happier

 

i use ethenol free gas 87 octane, and that alone got me better milage per tank. now that i have the supercharger ethenol free and 93 octane is all i run. yea its expencive, but i work offshore so i only drive my truck 6 months of the yr so i really dont care what the mpgs come out to being.

 

I ran 87 for my first two tanks after buying the it (used) and averaged around 15mpg. I'm all stop and go. Tried 91 for the next couple tanks and got 17+ mpg. I've been running 91 since. I just wish I could find a gas station that didn't use an ethanol mix.

 

What does anyone think about 85 octane at 5000 feet of altitude?

 

x2

 

If it's not knocking (which it shouldn't be since there is a knock sensor) you'll be fine. Maybe won't perform as nicely because the computer retards the timing when there is knocking.

right guys?

 

87 everytime, then a couple of tanks of 91 every 5k miles.

 

I think these engines run better with 91 octane. I pickup 2-3mpg with 91 vs 87 octane. It also seems to run smoother.

 

I'm not sure about the newer cars, but cars from the 80's & 90's didn't do well over the long haul when you ran straight 100LL. Muscle cars from the 60's & 70's did well when you mixed it with regular unleaded fuel.

I used to run 91 octane in my 93 Saturn when it was new. I would average37-38 mpg on the highway. The car was rated at 28-34. Of course there wasn't the ethanol mix and 91 octane was about $1.30 at that time. As many people have said, ethanol mixed fuel will cost you 2-3 mpg. I've only run 87 in my truck, but I might try 91 just to see what happens.

 

91 increases my hp. jk I have to cuz i'm boosted. When I'm not driving like a jack ass I get better mpg.

 

I convinced my mom to run premium in her Corolla (higher compression than the Taco) a year ago after driving it myself with both grades of fuel. A couple weeks ago she put in regular and the car's PCM spit out a random misfire code that didn't come back after it adjusted to the fuel. It dropped from a 39mpg average to about 35 which is more of a difference than the cost of the fuel.

I doubt she'll do it again.

After multiple tanks of premium in the truck the timing retard on startup only drops down to about 14º at cold idle instead of the 8º it used to do. Doesn't take so long to come back up to the normal 22º @1300.