I have a 2002 F150 S/Crew w/ 4.6L ..Ok i live Ca and my owner's guide pg 268 Talks about gas for youre truck and says to use 87 octane "" PREMINUM " UNLEADED gas is not recommend in the U.S Whats up with that ? what would happend ? and what about adding acetone to youre gas ? wont that increase the octane level? I plan on getting a super tunner too ?

 

What they mean is, use 87 octane, premium unleaded (92 octane) is not recommended, nor is it needed. Nothing bad would happen if you used 92 octane rather than 87, other than you'd be wasting money! If you do use a programmer or a computer chip, that may requre the use of 92 octane, depending on the chip, or the programmer, and how you set it.

 

What part of reading and following the owner's manual needs explaining?

Steve

 

Thanks alot for the reply steve D H

 

Using higher octane fuel will cause carbon build up in the combustion chamber.
Eventually this will cause detonation, leading to engine damamage.

 

Other famous quotes.....

Nixon "I am not a crook"

Sorry but not even close on this one.....

 

I guess what I see in the shop is not true?

The higher octane is "slower burning". So on an engine not designed for it, the unburned fuel turns into carbon build up on the valves and combustion chamber. These carbon chunks will flace off and can make valves stick open, smacking the piston.

 

In basics, the octane rating is just that, how much OCTANE is in the gas. When we refine our gasoline, we break the crude into its different hydrocarbon chains. The chains we use to make gas are HEPTANE and OCTANE. OCTANE has a chain length of eight hydrocarbons. HEPTANE has seven. HEPTANE becomes unstable when compressed and this property is used to ignite the OCTANE. When you put premium gas in the tank, it has less HEPTANE and the gas is harder and slower to ignite. It would be similiar to running the engine in a retarded timing condition. It can form carbon deposits, usually there is a slight lose of power and fuel mileage. I wouldn't recommend it for the Triton engines. Acetone, yes it will raise the "octane" rating but considering that you generally are mixing it at a ratio of 4 oz per 10 gallons, the effect is minimal. The best gain from acetone is that it relieves surface tension, thereby contributing to the atomization of the fuel. Better atomization= more power, cleaner burning, and better fuel mileage.

 

Open mouth, insert foot...

 

So i have a few guys at work putting acetone into there tanks "TEST DUMBIES" 1 a BMW and the other a Hummer H20 has anyone else tried it in there ford ?

 

The important point in this discussion, that pertains to Ford 4.6/5.4 and 6 engines, is that you have "no way" of advancing the ignition timing to take advantage of higher octane ratings of fuels.

The chip tunes for these higher octanes does indeed reprogram the ignition timing more advanced so the higher octanes are able to be used.
This type of change is known to increase engine torque and is not so much from the fuel but the "ability" to use it, given by reprogramming.
Since burn time is slowed, the timing needs to be advanced.
The advance is where the extra torque come from.

 

I'm not sure I believe much of this thread. The principal components of gasoline are benzene and ethane (formulations change all the time, this was true 20 years ago anyway). There are only inadvertent traces of octane. The octane rating is the resistance to detonation in a research engine, a single cylinder engine with specific cylinder wall and head temps, RPM, compression, etc. A formulation of gasoline is rated relative to what running on pure octane would be.

As to the carbon deposits, I'm not sure. The key to higher octane fuels is that higher temperatures are required to ignite them, this is what prevents heat from compression, carbon deposits, sharp corners on heads, etc from lighting them off. That may make the slower burning and that could lead to deposits. Interesting thought.

It's true that the computer is tuned for low octane gas. It's also true that higher octane fuels do NOT have more energy. But higher octanes allow engines to be designed more efficiently (higher compression and more spark advance) so the effect is more power from the high octane gas. This is only a secondary effect and will ONLY help engines that are knock corrected but here goes. If the knock detector detects knocking or pinging, it will retard the spark advance and may increase EGR and may enrichen the mixture. You'll probably not notice when this happens. But if your engine runs this way often, running a higher (knock resistant) octane will keep it from knocking, and therefore from the retarded spark and other corrections. If your engine doesn't knock (you wouldn't hear it, it would be corrected before it was audible outside the engine), higher octane wouldn't help.

As to a chip tuner 'realizing the benefit' of higher octane. The two big wins for engines designed for higher octane are the higher compression ratios and the more advanced spark. The tuner can advance the spark more, but it can't do anything about the compression. Therefore, it can only take a small advantage of increased octane.

Someone is likely to know more than I do about this and correct this, but I think it's all correct.

 

You bring good additional points.
Modern fuel is quite a soup mix and has a lot shorter shelf life and is photo sensitive to beak down when exposed to light.