Octane question (For the Octane Savvy)

Trey, This is a loaded question. First, there are no detergents in fuel. Second, there are additives and they are area specific, not brand specific. In most cases the fuel at the pumps all come from the same local refinery. Different states require different additive packages for ecology and weather reasons. These packages typically change throughout the year. The worst of these additives is MTBF. It is a form of Ether. This stuff is bad for everything, including the gasoline itself. It will cause seal deterioration, fuel gelling, skin damage, you name it. Generally, gasoline having this stuff must be used within 90 days or else. Next wives tale to smother is there is more power in 91 than in 87. Energy content is the same. Do not believe the label on the pump, you could be buying anything. There are simply not enough industry controls to validate conformity and eliminate cheating. Your best bet is to buy fuel from a station you have a successful history with. Lastly, never use more octane than your motor needs to be knock free, it is a waste of money. The actual octane level the engine needs is a product of engine design with consideration of the following factors. Mechanical compression ratio, camshaft timing, inlet and exhaust restrictions and operating temperature. Steve

"Trey" wrote in message news:J07oe.55738$ snipped-for-privacy@tornado.socal.rr.com...

Just a follow-up 87 burns at a faster rate than 91 octane fuel. Also, use what your owners manual or the manufacturer recommends. I know my autos say use 87 and my bike says use 87 or higher. I use higher because it prevents knocking when the bike gets hot especially in traffic.

Coasty is correct; 87 octane gasoline does burn faster. Regarding the previous poster's comment about refineries, that too is correct. Gasoline is gasoline. The refineries all crank out 87-octane Regular-Unleaded. What makes the difference in 87 or 89 or higher octane gasoline is ADDITIVES. Contrary to urban legend 91 (or 93) octane gasoline is not more highly refined or more "pure". Gasoline is gasoline, period.

When your vehicle runs poorly on a certain brand and better on a different brand (octane rating otherwise being the same) likely what is causing the performance difference is the additives. Different brands use different formulations based on their own research and marketing.

Yes, gasoline is also custom-blended for different areas, altitudes, seasons and emissions performance.

You are wise to follow your owner's manual when selecting the fuel octane rating. If your vehicle performs poorly on the recommended octane then perhaps you should take it to the dealer to find out why.

Using a higher-than-recommended octane is foolish. It may give you a warm, fuzzy feeling to squander money needlessly, but you're impressing no one.

To date, with about 38 years behind me in the trade, I have NEVER experienced an engine running worse on 91 than on 87. I have never seen mileage decrease by using higher octane fuel. I HAVE seen many engines that specify regular fuel run much better, and get better mileage, on super.

As for the additives, refinery capacity is shared, but additive packs are added at the tank farm - often directly into the tanker, and these additives ARE brand specific. Some ARE detergents. Some are oxygenators. And SOME premium fuels will definitely help the engine run cleaner.

Some additive packs cause problems too, like the problem over the last few years with fuel guages on some models of vehicles using Shell ( and apparently one or two other brands) fuel.

There are more problems with different BRANDS of fuel causing engines to run better, or worse, than with different octanes, per se. It depends what is being used as the octane booster in the fuel. Some of the "Equine Urine" being sold as gasoline in some parts of North America won't run right in a car requiring 91 OR 87 octane.

Actually the additive packages AND detergents are different between most brands. Techron is a detergent package that is advertised as such, but most companies have a similar package as well. These are needed to keep the entire fuel system clean and functional. They reduce gum formation and break down any existing deposits. The base stock MAY be the same for each brand though. The states themselves do NOT require different packages, however the companies may change formulations to help reduce the effects of the seasons on emissions.

Yes. The above specifications are intended to ensure minimal quality standards are maintained, however as well as the fuel hydrocarbons, the manufacturers add their own special ingredients to provide additional benefits. A quality gasoline additive package would include:-

• octane-enhancing additives ( improve octane ratings )

• anti-oxidants ( inhibit gum formation, improve stability )

• metal deactivators ( inhibit gum formation, improve stability )

• deposit modifiers ( reduce deposits, spark-plug fouling and preignition )

• surfactants ( prevent icing, improve vaporization, inhibit deposits, reduce NOx emissions )

• freezing point depressants ( prevent icing )

• corrosion inhibitors ( prevent gasoline corroding storage tanks )

• dyes ( product colour for safety or regulatory purposes ).

During the 1980s significant problems with deposits accumulating on intake valve surfaces occurred as new fuel injection systems were introduced. These intake valve deposits (IVD) were different than the injector deposits, in part because the valve can reach 300C. Engine design changes that prevent deposits usually consist of ensuring the valve is flushed with liquid gasoline, and provision of adequate valve rotation. Gasoline factors that cause deposits are the presence of alcohols or olefins [46]. Gasoline manufacturers now routinely use additives that prevent IVD and also maintain the cleanliness of injectors. These usually include a surfactant and light oil to maintain the wetting of important surfaces. Intake valve deposits have also been shown to have significant adverse effects on emissions [47], and deposit control additives will be required to both reduce emissions and provide clean engine operation [48]. A slightly more detailed description of additives is provided in Section 9.1.

Texaco demonstrated that a well-formulated package could improve fuel economy, reduce NOx emissions, and restore engine performance because, as well as the traditional liquid-phase deposit removal, some additives can work in the vapor phase to remove existing engine deposits without adversely affecting performance ( as happens when water is poured into a running engine to remove carbon deposits :-) )[49]. Chevron have also published data on the effectiveness of their additives [50], and successfully litigated to get Texaco to modify some of their claims [51]. Most suppliers of quality gasolines will formulate similar additives into their products, and cheaper product lines are less likely to have such additives added. As different brands of gasoline use different additives and oxygenates, it is probable that important fuel parameters, such as octane distribution, are slightly different, even though the pump octane ratings are the same.

So, if you know your car is well-tuned, and in good condition, but the drivability is pathetic on the correct octane, try another brand. Remember that the composition will change with the season, so if you lose drivability, try yet another brand. As various Clean Air Act changes are introduced over the next few years, gasoline will continue to change.

I have Octane Boost and am inclined to experiment w/ it. It will increase octane as much as seven points. Recommended for off road and racing. Any thoughts or feedback on that?

What kind of timing, compression, cams, or boost are you running, and on what engine? Bone stock Dodge Ram, you will be disapointed...

More info on Octane

Also,

Most owner manuals state use 87 not because it runs the best on them (because most modern high compression engines realy do not) but because of for marketing reasons. It would kill sales if they labeled their vehicals as requireing higher octane fuel. Also, the difference in burn rate is minimal but oremium does burn just a bit slower but it does have a higher pre-igniton point than regular. Also some fuel do have a "detergent " addive of sorts to keep injectors clean and some even use a additive to minimize or prevent formation of ice crystal in fuel in extreme cold if moistue is present in fuel in small amounts.

So would a bone stock 1995 Dodge Neon benefit from 91 over 87??

highly

You are in error here. They crack the base stock differently for hi octane fuel it is not the product of additives, it is not that easy (like in the leaded fuel days when they added tetryl lead). Most refiners make a 87 and a 91 to 93 octane fuel and they mix the two for plus grade and some stations mix the two themselve on delivery to your tank and some have plus tanks under ground but 87 and 93 IS NOT the same gas base stock with additives added to increase octane, it is a different "cracked" and cooked brew all together though some would like to believe otherwise. There is also 100LL av gas (a different brew yet) and they used to make a 110/130 octane leaded aircraft fuel for the old big piston aircraft of the 40 and 50?s that are still in service and as some of them are still flying today, someone must still be making the fuel for them too off yet another base stock. I might also add that as you "cook" the fuel longer to raise the octane and distill out the elements that lower its octane rating, you also lower the BTU content of the fuel so 93 octane does have a few thousand less BTU per gallon of fuel than 87 does just like deisel which is refined even less has even more BTU content than gasoline does.

Lower octane gas does burn faster than high octane but only under identical combustion chamber conditions. Octane is nothing more than a measure of the anti- knock characteristics of a given fuel. Running higher octane than what the manual calls for or throwing in those bottles that raise the octane level only keep company CEO's happy and your wallet thinner.

Jerry

If it is a twin cam, most definitely, as the manual calls for 91.

The engine code is ECB, Compresstion Ratio is 9.8:1, SOHC Valves, SFI Fuel Injection.

That depends, if you drive it in hot weather with A/C on, it will likely run a good bit better because it will either ping like crazy or retard the spark so much to prevent it that it will lose power and performance. If you drive in cool weather and do not use A/C you should get by on 87 just fine.