Difference with high octane?

Except it does. These trucks have dedicated low and high octane ignition maps.

 

For what it's worth, that Engine Master's video is using an LS3 engine which does not have variable valve timing.

 

Thats comparing apples and oranges. the 3.5 isn't even close to an LS motor wise lol.

Yall need to stop trying to be YouTube mechanics.

 

There is still timing adjustment in an LS but comparing it to a Toyota 3.5 is miles apart.

 

Been a lot of that going on lately... Especially in the 4GT section.

 

I can say this, I get 2-3mpg better with ethanol free 90 octane

 

Al my Japanese brand vehicles got better MPGs and ran better/smoother on 91E0 or higher.

My truck is a beast running premium SFOB tune on 94E0.

 

Try some plane fuel see what happens lol she’ll run like a scaled dog.....lol no seriously I do agree I got a 94 single cab z71 I run high ethanol in her she doesn’t run as smooth and mpg as the high test non-ethanol seriously ....plus the ethical crap coats and draws moisture believe it or not over time what do you think it would do?.. So whenever I can or usually I run 91 non ethanol in my rides.....my wife does too but she’s got turbos in her rides lol

 

Is there an OBD application that can display ignition timing and knock suppression( retardation)?

That would provide "cause and effect" evidence of why high octane was "more better".

 

interesting. it's only 15 cents more for 93 here versus 89 octane. about 75c more than 87 for 93 ethanol-free.

 

any idea what the highest octane the ECU could realistically take advantage of on a stock tune? i'm guessing 91. figured the tuners would know more than anyone.

 

I ran 92 . You would need to get a tune to see potentials of high octane or even 87.
Even OG OV 2.0 tune has the same problem.

 

tuners with ott and kdmax both told me that even without a tune these trucks make more power throughout with higher octane fuel. almost all modern vehicles will make more. they are constantly adjusting timing and fuel trims to an extent to take advantage

 

I'll respond to you since it was you who I responded to yesterday.

I was wrong. I put in an effort to learn more, and while I couldn't find anything regarded objective measures of performance for our trucks based on octane rating, I'll concede I was incorrect about the effects of octane on timing.

 

sure, the timing will advance on High octane vs 87. But on stock ECU, 92 performance was pathetic. Those red vertical lines are pings that I heard.
Tacoma ECU is not handling high octane well without modifications to Ignition, Knock , Valve timing
Your cases could be different, but it was not worth for me to pay extra per gallon.

 

So, this has always interested me.

Advancing timing can improve performance, it does so because the fuel in the cylinder takes time to completely ignite and you want complete ignition to happen when the cylinder reaches top dead center (or just about). Since it takes time you need to ignite the fuel BEFORE tdc (advance).

In short, how much advance you have is a measure of how INEFFICIENT the ignition burn is, more advance is a slower burn, short advance is a faster burn.

Here is the thing, you advance ignition on the SAME engine using the SAME fuel because as much advance as you can get makes the most power, ALL OTHER THINGS BEING EQUAL. To the same point, engine designs with more efficient combustion chambers (chevy heart shaped vs hemi) use LESS advance. So, change something but keep the fuel the same then less advance is better. Said quickly, a short fast burn is better than a long slow one.

Wouldn't that imply that the fuel with MORE ignition advance is the LESS efficient fuel (the slower burn)? Again, yes, I know how ignition advance works and why you do it, but you do that to the same engine with the same fuel, if you change something (like fuel) then the one with the lower ignition advance would be the one with the MORE effective combustion would it not?

If high octane fuel has more ignition advance then it has a slower ignition burn which is less efficient. It also has less energy as well.
-That doesn't sit well with observed fuel economy improvements however...

 

i wonder why it still pings with higher octane fuel? i'm guessing ECU will just constantly advance the timing until it senses knock, then backs off a bit. the service manual even states some light pinging is normal under heavy loads.

 

Interesting…..I’ve never heard any pinging

 

it's not easy to hear it. you can see it pull timing in real-time with a OBD reader/scan tool though. it's very light pinging.

 

I didn't read the whole thread. I use the cheapest gas available. I added a pedal commander and increased my range by 55 miles per tank.