I have to recind my earlier post that you can find 94 Octane at the Sunoco in Woodbridge Va. I went by there this morning for gas and to my surprise they only had Ultra 93, not Ultra 94. Sorry for the bad information.

 

Cant using too high of octane be bad for car. I mean if it calls for 91 its better to have 93 than 89... but If you go high enough that can harm your car too I thought.

And 91 is the "premium" of all the pumps around here. regular is 85 and mid grade is 88.. I am in Utah

Oh and searstream, you said only one truck showed up, but I think most tank trucks have the capacity to carry multiple grades in thier truck. Like having three seperate tanks inside the trailer.

 

No big deal. I suspect this will be the case all over the area.

Thanks for the update.

 

I just started burning 87 octance in my 04 TL just to see what it does. So far, no pinging, and the gas mileage seems to be better, which is weird. I reset my gas mileage reading and I have gone about 50 miles so far, a mixture of city and highway, and I have gotten 25 so far. I usually average 22 to 23. Anyone else tried this and what are your long term results. I am on a 36 month lease and plan on selling the car pretty soon, so I am not that concerned about long term damage.

 

WTF...$1.22?

 

The HIGHER the octane (RON), the LESS Volatile the gasoline. Period.

If you think different, you are wrong.

Higher octane fuels are used to prevent pre-ignition, ping and/or knock. Why do they prevent pre-ignition, ping and knock? Simple, they resist the initial burn and are less volatile. Higher octane fuels DO NOT mean or equal more power, torque and/or fuel economy. They just do not work like that.

High compression ratio engines, turbocharged or supercharged engines are all KNOCK constrained. What determines this is the cylinder pressures. As the cylinder pressure rises, the need for more octane is required.

Heptane which is technically gasoline has a chemically correct formula of 14.64:1 (some of you say 14.7:1 which is fine). Octane is an organic compound that is added to heptane to DECREASE the volatility of the fuel. Lead was added to fuels to decrease the volatility as well. We don't use leaded fuels in late model pollution control vehicles and longer.

For one, lead is very environmentally unfriendly. The lead will react to the catalyst in the catalytic converters and ruin oxygen sensors. I can't imagine lead would be friendly for the new pintle style fuel injectors as well.

Some of you will argue with me and tell me how you car feels "faster" with HIGH octane gasoline or race fuel. That's fine, but the STOP (seat of the pants) meter is almost always wrong.

Most cars with KS (knock sensors) detect the onset of knock well before a human can hear it. The frequency of vibration triggers the KS to retard the spark timing. 1 degree of spark on a supercharged engine is worth approx 4-5 HP and 5-10 lb.-ft of torque.

An example, so if you have an engine that requires 91 octane fuel and you are using 87 octane the KS might be activated. The computer pulls 3 degrees of spark timing and you've just lost 5-6 HP (n/a engine is worth about half the power depending on the engine). Then you decide to try 93 octane and poof...the car feels faster. Did you make any more power? No, you made the power you should have been making all along. Except now the KS isn't being tripped.

If you added 100 octane unleaded fuel to you stock TL it will not make any more power or run a faster 1/4 mile time. NO WAY...NO HOW!

The only way to make the engine respond to the increased octane would be to tune it and add more spark timing (if possible at all). Perhaps a 2-3 degrees more spark could be added, but it depends on the engine dynamics. Would the ECM detect the additional octane and increase the spark on it's own...NO.

I've seen Lincoln Mark VIII guys pull this magic trick on the dyno and claim more octane means more power. The Mark VIII uses a 4.6L DOHC V-8 and by default the engine is knock constrained right from the factory. As a Ford engineer once told me, those cars are almost always into the KS right off the showroom floor.

So add 100 octane fuel, 1 heat range colder spark plugs and a 180 degree t-stat and boom the car made an additional 10-15 RWHP on the dyno. Or did it? No not exactly. The power is usually exactly where it should be but without triggering the KS to activate.

Should you even consider high octane fuel for your stock TL? If you do you are just wasting your money. 91 octane is recommended and that is what you should use unless the engine pings or knocks. Then you move up a notch.

Also please don't argue about alcohol based fuels being the best thing since sliced bread. Please consider what it takes to even produce E85. Lot's of electricity is required to turn your favorite ear of corn into fuel for your car. Where does the electricity come from? Think about it.

There are many disadvantages to using alcohols, particularly methyl and ethyl alcohol. When used near their stoichiometric air/fuel ratios can produce more power, however a much...much larger quantity of fuel is required. Why?

Alcohol has a chemically correct formula of 9:1. So you need nearly twice as much to produce the same results at stoich. Yes that's right. So if a gallon of gasoline is $4.00 and a gallon of E85 is $2.00 but you are using twice as much E85 than gasoline, what have you gained?

Yeah its a way to get away from using 100% fossil fuels and the combustion process is cleaner then straight gasoline. Cost wise and energy wise...no it won't save you a penny.

Some of you will remember Vapor Lock. The relatively low boiling points and high vapor pressures of alcohol based fuels would cause problems with vapor lock, especially on a hot day.

Alcohol is higher corrosive and tends to absorb water. This means the fuel systems would have to be upgraded to deal with the corrosiveness of alcohol based fuels. Even been to a track and seen an alcohol fuel race car? Ask those racers how often they have to change their fuel lines and rails.

A-Train

 

a-train, my friend, you are very wise. he is totally correct, octane has absolutely nothing to do with hp, more octane only means that the gasoline is more resistant to detonation from compression(the more pressuree exposed on somthing, the temp rises) until it is actually exposed to a flame

 

A-train Outstanding! I have worked will fuel research in the past and you say it right on. We actually found the drivability of mid-grades better than 91 octane? The engine must be designed fro higher compression, like the TL, to take the most advantage of higher octane.

ML

 

Props to atrain for the great explanation on octane ratings.

I was talking to a (non-acura) car engineer, and he said it didn't matter what octane rating you used, as long as the car has a proper KS. The KS would retard the timing so the engine would work fine just with less power.

Believe it or not, he also said that some (very premium brand) manufacturer does not have a proper KS system, since they require premium fuel. This means for their products, if you put in low grade fuel and it knocks, you can seriously f*ck up your engine.

1 more reason to love your Acura, since they recommend premium but not require it.