unless you have a supercharger, or are pinging, run the 87FortPieToyo said:
unless you have a supercharger, or are pinging, run the 87FortPieToyo said:Just got a '04 4x4 Tacoma, V-6 Auto and I was wondering if it really makes a difference on which octane I use. I'm talking about long-term, as well as short-term performance (which I know should be ever-so-slightly higher with the 93). I already ran about 4 tanks of 93 thru and want to make the decision now whether to stay with 93 forever, change over to 87 forever or alternate on some kind of basis. Thanks.
BigBadBob0 said:On a normally timed, normally aspirated 3.4l performance is actually lower with 93 vs. 87. Run 87. It's better for your truck and your pocket book.
I get a little long winded sometimes and get carried away.. lol.. Gas / oil companies and Bank of America are two of my pet peeve companies..BigBadBob0 said:In case you were wondering, David, you're 100% rightI had hoped that my mini version of your post would get that point across.
Actually in the manual they say 91 research octane number (RON), whereas on the pump they only give you the average octane number (R+M/2). Reportedly, sensitivity is almost as important as average octane number, but see if you can find that on any pump!!!03trdblack said:You know what's funny though, the 2003 Factory Service Manual for the Tacoma says they did all their engine testing with 91 Octane fuel. This was also the fuel they used to post the horsepower/torque ratings from the factory. It really made me wonder why they would do testing with the higher octane and then recommend the lower octane rating....
I think you missed the point, they say 91RON, this is not the same measurement as they quote on the pump when you go to fill up. The 91 is not the "octane" of the gas that everyone knows about.GoodyearMTR said:Probably because they advance timing so much they would get detonation if they didnt run 91. They would advance timing to increase power output.
What everyone else said. They can't get away with running 91 octane for the testing and then recommending 87. The 91 listed in that manual is research octane number, the "R" in (R+M)/2. The "M" is motor octane number, which is a lower number. R and M are averaged for the octane that is posted on gasoline pumps are required by federal regulation.GoodyearMTR said:Probably because they advance timing so much they would get detonation if they didnt run 91. They would advance timing to increase power output.
I dunno about that. If your ECU retarded the timing at 4700 rpm then what made it instantly jump up 20 hp by 4800 rpm?TRDOLMAN said:If you look at my dyno run sheet from the webshots link in my sig, you will see at 4700 RPM the knock sensor caused the ECU to pull timing. We never heard any detonation. Look at the momentary drop in HP and torque at that point. The ECU pulled timing even though I have fuel mods, water injection, and was running AFR's at 12.1 to 12.5.
What I was told by the "experts" is that, contrary to what I thought, the ECU will try and add timing back instantly and apparently that's what it did at 4800 RPM. I always thought that once the ECU pulled timing, it took a long time to advance again once the knock sensor settled down. I guess the "experts" were right and I was wrong. I am still trying to learn about these things. This is my first time trying to mod a computer controlled engine.flatlandtacoma said:I dunno about that. If your ECU retarded the timing at 4700 rpm then what made it instantly jump up 20 hp by 4800 rpm?
Bah, I'm still skeptical. The ECU does start adding back timing as soon as the knock disappears, but it is supposed to be a more gradual slope than it took it away by. I don't see that at all on your dyno sheet. There are more sensors than just the knock sensor that will advance or retard your timing, if that is even what is going on there.TRDOLMAN said:What I was told by the "experts" is that, contrary to what I thought, the ECU will try and add timing back instantly and apparently that's what it did at 4800 RPM. I always thought that once the ECU pulled timing, it took a long time to advance again once the knock sensor settled down. I guess the "experts" were right and I was wrong. I am still trying to learn about these things. This is my first time trying to mod a computer controlled engine.
Dave