87 octane vs 89 octane

[robchalmers]

is Octane a Universal rating?? just I think we're a it spoiled over here our 'regular' is 95Oct and 'premium' 98-99 depending on supplier. in previous cars i have noticed FE increases on AA-BB-AA-BB tank fulls of reg / premium. Sadly due our unelected dictatorship taxing us soooo much and the margins the oiler but in, that although mpg is increased cost-per-mile can be lower and at the end of the day thats what I'm after PPM (pence per mile, how old skool!)

[instarx]

Originally Posted by kill-9

I recently (a day after I joined the forum) filled up all but about 3 L of my tank with 89 octane. I've been told that depending on the car, it can make a big or small difference. so far, Ive gone through roughly 34L of my tank and I am at 400 KM, making it 8.4 L/100KM (27 MPG) which is WAY better than my previous 13 L/100KM (18 MPG). So far it looks to be worth it.

Psychologists know that something called head-factors bias experiments all the time. It is almost impossible for humans to not unconciously bias results. The only way to know is to get your wife to fill up with either 85 or 87 octane, write down which, and then not tell you. After a few months of recording mileage unbiased by your expectations you can "open the sealed envelope" to see if octane really made a difference.

[instarx]

Originally Posted by Frank Lee

Kind of a leap to conclude that if E85 (roughly 85% ethanol) drops fe "27%" that E10 (roughly 10% ethanol- 75% less than E85) yields only 7% different results??? I've never experienced anywhere near a 20% fe drop because of E10.

Agree. I can't find it now but a recent technical study of various ethanol blends showed that all cars have sweet spot ethanol blend where mileage is at its maximum - higher than either pure gas or E85. Some crs showed significant improvement at their sweet spot, others only a small amount. They tested several cars, including some that were not flex fuel. Sorry I don;t remmeber details but sweet spots were generally between E25 and E40. Maybe someone can find it with google.

[tjts1]

Originally Posted by ih freak

Is your 850 turbo or non-turbo? Mine is the non-turbo. I love the car though...300 thousand miles and still ticking.

Non turbo. Check this out
http://www.matthewsvolvosite.com/for...&sd=a&start=56
You'll most likely pickup some MPGs in the process and you should be able to run on 87 octane most of the time without a problem.

Originally Posted by robchalmers

is Octane a Universal rating?? just I think we're a it spoiled over here our 'regular' is 95Oct and 'premium' 98-99 depending on supplier.

No. In the US octane is calculated by the formula (RON+MON)/2. In the UK and most of the world its simply RON.
http://en.wikipedia.org/wiki/Octane_rating

Our 87 octane is equivalent to your 91-93 and our 92 is around 95-97 in the UK. Generally speaking the US has lower octane gasoline than the UK and europe but the difference is not as big as the raw numbers would suggest.

[Frank Lee]

Originally Posted by instarx

Agree. I can't find it now but a recent technical study of various ethanol blends showed that all cars have sweet spot ethanol blend where mileage is at its maximum - higher than either pure gas or E85. Some crs showed significant improvement at their sweet spot, others only a small amount. They tested several cars, including some that were not flex fuel. Sorry I don;t remmeber details but sweet spots were generally between E25 and E40. Maybe someone can find it with google.

Study Finds Certain Ethanol Blends Can Provide Better Fuel Economy Than Gasoline | Auto Newswire Article from Motor Trend

[pgfpro]

Originally Posted by Frank Lee

Study Finds Certain Ethanol Blends Can Provide Better Fuel Economy Than Gasoline | Auto Newswire Article from Motor Trend

Wow!!!

I might have to try out some different blends to see if I can make some improvements.

I already have a 55galllon drum of E85 I use for racing.

Nice find!!!!

[2000mc]

in the motortrend article i dont see where it says anything about more / better mileage.

Previous assumptions held that ethanol's lower energy content directly correlates with lower fuel economy for drivers. Those assumptions were found to be incorrect. Instead, the new research strongly suggests that there is an "optimal blend level" of ethanol and gasoline--most likely E20 or E30--at which cars will get better mileage than predicted based strictly on the fuel's per-gallon Btu content

this sounds like a fancy way of pushing ethanol with new and improved "less loss than expected"

[Frank Lee]

Jeezus, you didn't even read it didja?

[jasonck08]

I use to drive a 26cc stand up scooter with a Tanaka engine. It would run on standard 87 fuel, but I typically ran it on 98 octane + octane booster, aprox 100 octane. It definitly ran about 2mph faster with the higher octane.

With that said, I know where talking about cars mostly, but every engine is different and if MPG is different that will depend on the compression ratio of the engine etc.

[2000mc]

nope, didnt, looked like re hashed version of

http://www.ethanol.org/pdf/contentmg...yStudy_001.pdf

back when it didnt work for em at all except with some wierd denatured alky/biodiesel stuff i've never heard of....
...but now i see they have

http://www.ethanol.org/pdf/contentmg...inal_12507.pdf

now they think they have something but they dont... they forgot to bring a gm tech to thier tests...

theyre excited about a chevy that cant handle the test because they dont use actual fuel sensors anymore, and only recalibrates to adding e0-e10 or e85, it cant handle adding mixtures in between, you can drive on e10, add some e85, and have a tank of e30 just fine.... but dump in e30, what will happen isa crapshoot.


from gm SI fora 07 impala
E85 Flex Fuel Description

E85 compatible vehicles no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle calculates the alcohol content of the fuel through measured adjustments.

The ethanol calculation occurs with the engine running after a refueling event has been detected via a measured change in the fuel level sender output. The virtual flex fuel sensor (V-FFS) algorithm temporarily closes the canister purge valve for a few seconds and monitors information from the closed loop fuel trim system to calculate the ethanol content. This logic executes several times until the ethanol calculation is deemed to be stable. This may take several minutes under low fuel flow conditions such as idle, or a shorter time during higher fuel flow, off-idle conditions.

Air-fuel ratios and the corresponding ethanol percentage are updated following each purge-off sequence. the fuel alcohol content percentage value can be read on a scan tool.

When an E85 compatible vehicle is built, an ECM replaced, or if the learned alcohol content has been reset with a scan tool the fuel system will need to contain ASTM gasoline with 10% or less ethanol content.

A minimum of 11 Liters (3 gallons) must be put in the tank in order for the vehicle to recognize a re-fueling event. It is not necessary to turn the ignition off in order to have the re-fueling event recognized; however local safety regulations should be followed.

After the re-fueling event, the system registers the amount of fuel that was added, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines if the fuel added was either ASTM Gasoline or ASTM E85. Based on that determination, the system adjusts to the expected alcohol mix in the fuel tank, and then the fuel trim and O2 sensor activity fine tunes the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or E85 to gasoline, can result in driveability symptoms due to the inability of the system to adjust for fuel composition by not attaining closed loop operation.