bubbabud

Schmucks is way to polite but I guese this is a mixed company site. Bubbabud.

Cowboy Ron

The ECMs in the motor should comp for whatever fuel we put in them but, if the higher octanes have more BTUs then I would think that would equal more power to the wheels.

Any thoughts on this?

sbronemann

The reason I ask that is because here in Iowa, there is no such thing as 85 octane. Minimum any pump in Iowa is 87. Most stations are 87, 89, 91. Wal-Mart Murphy stations have 89, 91, 93. So I was confused by that

bubbabud

Higher octaine gas does not have more btu infact it has less it is harder to ignite and burns slower but your ecm on a modern engine will recognize this and adjust timeing and fuel which will improve performance however the performance improvement will seldom match the increased cost of premium fuel note if you want more btu energy its spelled DIESEL. Bubbabud 2011 XLT SC ECOBOOST

pfbz

The key benefit of high octane fuels is to allow the engine to run in more extreme conditions (heat, altitude, load) with more timing advance, and not have pre-ignition (knock).

But that does not mean the ECU will necessarily run more advance with premium fuel than with regular. The ECU is only going to advance the timing so far, no matter what fuel you are using.

If lower octane fuel combined with the operating conditions does not cause knock, then the ECU will not pull advance. There is no advantage in this situation when using higher octane fuel, for mileage or performance.

If lower octane fuel combined with the operating conditions does cause knock, the ECU will retard timing. This is where higher octane fuels have advantage... They allow the ECU to run more advance, with more performance and more MPG.

Unfortunately, there isn't really any easy way to see if the ECU is retarding timing with lower octane fuel. Some might think they can feel it, some might think they can see the difference in MPG, but really the only accurate way to tell would be to observe the OBDII timing data while you are running.

In general, if you are running in environments with some combination of hot temperatures, heavy loads, high altitude, or steep climbs, then with 2011 Ford engines like ecoBoost, you are likely to have some advantage to high octane fuels. Otherwise not.

But if you really want know what is going on, get an PC or smartphone application that allows you to view OBDII parameters like "PID 0D, degree's of timing advance" and you can see when/where your engine controller starts to pull timing.

Even that isn't 100% though, as he ECU will also pull timing for many other reasons... Warm up, perhaps even to soften a shift point, etc. so you really want to pay attention primarily during high throttle applications with the tranny locked into a particular gear.

GlennRMK

Here in Montana we have 85.5, 88 and 91.

I'm going to try running different grades from the same station to see if mileage varies at all.

I know most of the time the 91 octane here has no ethanol in it while the other grades do, so 91 might be an even bigger advantage.

Also, sometimes mid (88) is same price as regular because it has ethanol so I will be avoiding that.

klumb15

Higher octane gas typical DOES have more BTU's per content. I say typically because most stations have E10 as 87 Octane, E5 as 89 Octane and 91/93 as E0. Gasoline has more BTU content than ethanol no matter which way you slice it. If it wasn't for this known fact, BTU content is not a function of octane what so ever and higher octane fuel certainly doesn't contain less BTUs..

ken75ranger

That is going to depend on where you live-buy fuel. In NY is all E10 for every grade of gas in most counties.

Yippie21

I have gone back and forth, but here in the DFW area, our stupid EPA mandated 10% ethanol blend @ 87 octane makes my EB run like crap compared to 93... So I've been biting the bullet and just running 93. I like the way the engine responds to the 93. Now, when I've bought gas outside of the area, the non-ethanol 87 runs just fine. I blame ethanol, the EPA winter/summer blends, etc.

Shan

The blend on the pumps will usually state "up to 10% ethanol". Seeing how ethanol is an octane booster you'll usually find more in the 93 octane fuel than the 87.

In MS area anyway.