hi guys and gals just wanted to know if i would notice any inprovment with 93 octane insted of the 91 i found a place that sells 93 on the way to work one day i live in the sooner state and mostly have 91 here i going to buy 9100 soon and wanting to know thanks 72 mustang p.s have 5.4 screw

 

Hi 72,

Yes, there is indeed enough additional performance & fuel mileage available to make it worth having us tune for 93 octane instead of "only" 91 octane.

But don't forget, with the 9100 we can set it up with 3 different custom tunes - so we could do one for 87 octane, another for 91, and then the last for 93 octane, if you like. Or, we can do a max performance tune for 93 octane (which is basically a "sprint" tune, designed for quickest 0-100 mph acceleration, that can still be used every day on the street but is just a bit too aggressive for a full Top Speed run), then a "street" performance tune tune for 93 octane that is top-speed capable - and then whatever you want in the first position - like maybe a fuel economy tune or a towing tune for 87 octane, perhaps.

Just give us a call whenever you're ready & we can go over exactly how you would like to have the 3 different tunes set up in the 9100, we can let you know just what all options we can give you, etc.

 

Unless you are going to make some programming changes to the truck, there will be no performance improvement. If your truck is getting knocking a little then it will help get rid of that and your anti-knock sensor will stop retarding your timing.

Higher octane actually has less energy. The rating number actually pertains to the fuel's flash point. With a higher flash point detonation can be controlled better (won't combust during the compression cycle with hot cylinder walls and carbon deposits, known as predetonation) so the spark can ingnite the mixture closer to TDC (top dead center) for a longer power stroke, which means more power at the wheels.

If you don't have any mods and your owners manual recommends 87 octane, save your cash and buy the 87. If you do any modifications that recommend higher or if you hear knocking and pinging, move up.

 

Hi Brian42,

Thanks for your post!

Actually, "72 Mustang's" original post pointed out that he was going to be using the 9100 - which is our custom Micro Tuner with performance tuning. So that being the case, as I stated originally, yes, there *is* more power to be had by having us tune for 93 octane instead of 91 octane.

Additionally, it is NOT automatically & always true that using higher octane fuel is a complete waste of money on the stock tuning - though to be fair, I'm kinda-sorta "splitting hairs" here, as I'd be the first to say that I wouldn't spend the additional money on additional octane that the motor is not specifically tuned for, as you usually don't get enough additional mpg to *justify* that additional expense in these F-150's.

In reality, that actually depends on how the knock sensor system is set up (calibrated) in each individual vehicle's computer code (PCM revision/calibration), and that varies widely in these trucks. For example, some will allow as much as 8 more degrees of timing as long as the knock sensor does not detect detonation (and here we're talking about one specific form of detonation, "pre-ignition") - but the other catch is the actual *rate* at which that timing comes in. It's usually slow enough (say, only 1 degree every 2 seconds at the same TP & load) that it's just not worth spending the money as you don't get enough additional fuel mileage to offset that cost - UNLESS the truck is actually tuned for it's use. There are some F-150's (a good number) whose knock sensor system calibration cannot add any timing when detonation is not detected, while others can add only another 2 degrees of timing, but can do it pretty quickly - again, this varies widely in these F-150's. You can take 20 trucks of the exact same configuration & model year, and have 13 different knock sensor calibrations.

I generally *do* agree that as long as the engine is not specifically tuned for the higher octane in the borderline knock table, it's not going to be worth spending the additional 20 cents per gallon as compared to what can be had (both in terms of raw power and fuel mileage gains) if the higher octane is actually *tuned* for. These F-150's have more different PCM revisions each model year than virtually any other vehicle made - sometimes *hundreds* of different revisions each model year alone, and they vary widely in certain areas - such as how certain limiters are effected, how the knock sensor system is calibrated, etc. Just FYI........

By the way - on the subject of fuels & energy content - higher octane fuel does not automatically have "less energy." On the other hand, it is also false that higher octane premium fuels will always automatically have a *higher* energy content than "regular" fuels, as some assume (and as some oil companies have advertised/marketed) - more often than not, when there is a difference, it's usually in favor of the higher octane fuel. There is not any kind of "rule-of thumb" *either* way.

When dealing with *quality* fuels, the actual BTU content per gallon (or per lb.) of fuel usually does not vary much regardless of octane (in the 87-100 octane range, R+M/2). The actual energy content of gasoline is expressed by the oil company/refiner in terms of the number of BTU's per gallon - say, 110,000 BTU's per gallon, or 98,000 BTU's per gallon, etc. - and that is not "automatically" increased or decreased (all else being equal) based solely on the octane rating.

Another point that comes up from time to time regarding fuels & higher octanes is the burn rate - once ignited, the flame front propagates itself across the combustion chamber at roughly the same speed regardless of octane (again, when we're talking about fuels in the 87-100 octane range R+M/2), generally speaking - but getting it *LIT* - actually INITIATING the burn of the A/F mixture takes more time - both in real time and in degrees of crankshaft rotation, as octane rating goes up. This is *precisely* why it's generally considered close to a waste of money to use more octane than the motor is tuned for, more often than not - and I'd be the first to say not to bother using more octane than the motor is tuned for, I do agree with you on that, certainly. Using significantly more octane than the engine is tuned for will actually *reduce* power and fuel mileage, and can also cause MIL's, etc. just as the owners manuals for most of these vehicles mentions.

With higher octane, it's not just that we can make more power & mpg *if* we add timing - proper tuning dictates that we *must* add more timing to the motor to compensate for now much longer it takes to *initiate* the burn of the higher octane A/F mixture. The spark plug needs to get it's current with the piston further down the bore (BTDC) so that peak cylinder pressure still occurs with the piston the same approximate number of degrees *down* the bore (ATDC) - otherwise the engine doesn't make the power it should, and won't get the fuel economy it should, either - this is why most of these vehicles owners manuals specifically instructs *not* to use premium gas, as they are originally tuned for 87 octane from the factory.

In tuning, the BTU content ("energy") of the fuel makes every bit as much difference, if not more, than just it's octane rating. A low energy 93 octane fuel can be out-performed by a higher-energy 92 octane fuel, for example. Or take methanol-based fuels (far different from gasoline) - now they have a *very* high octane rating, but have only about 50%-70% of the BTU content per gallon of gasoline.

Just some quick general FYI...................