I live in North Carolina where they put ethanol in our gasoline during the winter. And our maximum octane seems to be 93.

I went to Pennsylvania and got some 94 octane from Sunoco. I don't think it was my imagination that the car ran MUCH better with this gasoline.

We do have much higher octane fuel available for nascar racing. But I heard that it is very bad to put this level octane in an every day car.

Is there a maximum octane that can go into a 2004 E55? Is there a way to safely boost 93 octane gasoline?

And does this higher octane really work with an E55? Or is it just my imagination?

 

.............A local consumer advocate in metro Atlanta did an expose on this a while back. His conclusion was that cars who's manufactures require (1 octane or above can safely run on 87 or 89 without any appreciable difference in performance and with no risk to the engine. Also, all those rental cars that fall into this category and all the loaner cars that MB, BMW etc give out are mostly filled with regular unleaded gasoline by the people to whom the cars are loaned and nothing happens to the car. Of course the long possible down side to this is engine knock.

............No saying that you should go to regular unleaded, but if indeed t6he above is true, then going from 91 to 93 or 94 octane should make no appreciable difference. Since the manual says fill car with 91 octane or above, at 93 you are already above the requirement. Now I wonder if your car drives any differently compared to someone who was using the 91 octane.

Ted

 

When they used to put put MTBE and Ethanol in the winter gas here I used to store 55 Gal drums of Prem. and I have a 33 gal. gas caddy. I also tended to drive my other cars more. You could just buy one 55 gal drum of unleaded racing gas and just put in a gal or 2 every tankful. I've used 108+ and some other stuff but I like the race gas the best. You're lucky that you can get 93 or 94 Octane. All I can get is 91 or 92. In some forgotten college textbook of mine is a formula for blending different octanes. The other problem with winter gas is that they tend to put a lot more shorter chain HC's in the mix to lower the vaporization temp. curve. This is a carryover from carburated days as far as I am concerened.

 

i can't tell the difference between 92 and 94. Both feel very fast

 

The deal with most racing gasoline is that it contains lead and that will ruin your catalytic converters and oxygen sensors after continued use. One of the highest octane fuels available that doesn't contain lead is a 100 octane unleaded that is available in select areas. It is a sunoco product called GT100 and you could use this everyday as it does not contain lead. Ted's post has merit if you are driving a Honda accord as you will not see any difference in performance between a lower octane fuel and a higher one because this engine does not have a high compression ratio or a supercharger. You are just throwing away the extra money it costs to use premium fuel because it is not needed. It is possible that the ECM in an E55 could reduce the timing with a car that is churning over 10psi boost if a lower octane fuel(even 91 octane) if any knock is detected by the knock sensors. Obviously, this would reduce performance. In a car such as the E55 you would be wise to use the highest octane available and 93 would be preferable. Of course, 91 could be used but it may affect your performance slightly.

 

I'm using Sunoco 100 oct 90% of the time.
When I get 93,I can tell the difference in performance.

 

And the higher 100 octane doesn't affect engine parts because it is burning hotter? I remember hearing that putting too high an octane in a car can burn up the valves.

 

Like lots of things gas is a blend. One thing about race gasses is all of them have more BTU per vol. than pump gas (hence more density). This = more power and, if the engine doesn't compensate, more thermal load on the cooling sys. etc. Now if it turned into power the heat load is minimal. There is race gas blended for blown motors and 2 cycle air cooled engines that takes more energy to vaporize. This gives a cooling effect. Just a little compared to Methanol but a good thing. Bottom line, Race gas is good. The higher perf. the engine, the better the effect. Octane is the resistance to detonation. That is a good thing. That allows higher temp and pressure withoug some percetage of the unburnt misture chemically combining all at once (whell, within millionths of a sec.) causing a big temp and pressure spike. This spike is the mechanical componets reacting to this sudden stress. Like sending shock waves threw metal. This keeps happening in the same part of the combustion chamber resulting in a hot spot. Bad stuff is happening. Too make the most the ECU would have to be reprogramed but you will see a difference, even if you don't.

 

Do all the Sunoco stations carry the 100, I don't ever recall seeing it.

 

http://www.racegas.com/gt100locals/default.asp
http://www.76.com/products/76racing.asp
http://www.76.com/76locator/

 

I can also tell the difference in performace when I use 100 octane vs 93. You can easily tell.

 

Where are you getting your 100 octane from?

-m

 

Wow, another thread on octane. Some truth and some myth here. The diference in one octane rating point may not be the significant factor.

Gasoline is made up of dozens of compounds all which have an effect on octane rating. (See https://mbworld.org/forums/showthrea...threadid=55111 for a somewhat complete list) Since each gasoline suplier is free to mix and match within certain limits, the BTU/gal, density, octane, flashpoint, vapor pressure, volitility, etc. can vary greatly. It has already been said that octane rating is the fuel's ability to resist detonation. It does not necessarily mean that it will contain or produce more power. It means that the gasoline was tested against reference fuels (made mostly of toluene) in a calibrated single cylinder engine. Once in your tank, the way your car reacts to Shell's 91 octane and Sunoco's 91 octane gasonline can be different due to the difference in blends.

Ethenol, like many other components in gasoline, is a fuel but in this case, it is an oxygenate. It has a higher octane rating but a lower BTU/gal compared to many other gasoline components. It will raise octane but lower power output slightly. If the gasoline did not contain Ethenol or other oxygenates, the octane rating would drop slightly but BTU/gal would be up. To take advantage of every last BTU without detonation, aromatics like Toluene are added to raise octane ratings. This is why you see your mileage and power drop in states where there are manditory oxygenated fuel requirements.


Oh yeah, you can run the highest octane unleaded gas you can find with out any problems in your car. It does not run hotter or burn valves, etc. It will only waste money if you run something higher than what your car can use.

 

Mundelein,Townline rd(RT 60) at the west end of the road,Clark station.