Hello all...got a little confusion regarding how fuels are rated...gasoline vs diesel and octane vs cetane. I was under the assumption that octane ratings...say 87 octane was a ratio of 87% Octane to 13% ?? I thought that octane was C8H18...and was the main constituant of gasoline. Am I wrong, if not what is the other 13% and does this formula relate to Cetane...is there C8H18 in Cetane? I believe that Methane is CH4, Propane is like C2H8, I guess I only know enough of chemistry to be dangerous to myself...anyone out there with a PhD in Chemistry???

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1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown

Cetane

Octane

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Probably should have gone there first b4 asking...Graci Aklim. Now I need some asprin.

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1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown

Tylenol 3 with codine or Oxycontin will help.

__________________
01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

I wish!!!

__________________
1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown

What? No drug pushers where you live or what?

__________________
01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Nothin but moonshine...and Mennonites...both will dull the senses in a righteous manner.

__________________
1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown

BUT, one is faster, the other is more fun

Gas with an octane of 87 will have similar resistance to burning upon compression as a mixture of 87% octane and 13% heptane. It does not have to actually be made purely of octane and heptane, it just says that it will have the same resistance to detonation as a mixture of 87% octane and 13% heptane.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Anyone know what the equvalent cetane rating of svo would be?

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82 300D....went to MB heaven
90 350 SDL....excercising con rods

Depends on the plant oil. Soy is around 38-40, high oleic safflower is like 48.
I'll look for the link...
The cetane number for most plant oils is between 35 and 40, i.e. short of the 45 necessary for diesel engines

Fuel properties of fats and oils

__________________
1999 E300DT (131,800) 154,000 Black on Black SOLD

2006 CLK 500 coupe Capri Blue on Grey (zoom,zoom)
47,000mi

04 VW TDI Passat 80,000mi
(Techno)

How to eliminate oil dependency through market-driven approaches.
“We could cut oil use in half by 2025, and by 2040, oil use could be zero,”
The Sound of Diesel Speed
Ode to MB

I know there is a gas station that sells "premium diesel" but for the life of me, I have no idea what they are talking about since they don't know either. I told them that premium diesel is over 45 cetane but they don't know.

Also there is another shop that sells 40 cetane diesel. Says so on the pump.

Anyways, just because it is 45 cetane, does it mean it is good? What if the BTU is lower? Is that going to help? Biodiesel is higher cetane but BTU is lower and the MPG seems a little lower to me too

__________________
01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

There are different methods used to calculate the octane rating of a gasoline; for example, you'll often see on the gas pump the method used to compute the octane metric. All the organic chem you need to figure the formula for methan, ethane, propane, heptane, septane, sextane, octane, nonane, dectane, lol or some similar names with the prefix giving the number of carbon atoms. Carbon wants four bonds; in a chain each carbon will have one bond with each carbon next to it in the chain (except the first and last carbon which will have three hydrogens) plus two hydrogens making a total of four. But, yes, it's difficult to know a useful and stable octane rating for your gas unless each station uses the same method to calculate octane.
You'e right, methane is CH4 (so the carbon has four bonds). Ethane is C2H6, propane is C3H8, butane is C4H10, etc. Just remember the first and last carbon bonds with one carbon and three hydrogens, and all the carbons in the middle bond with the carbon on either side (two), plus two hydrogens to make four bonds for the carbon.

#2 is all going to have very close BTU values (except winter blend). Cetane's importance is more critical when
ambient temperatures start falling. You want to have that quick detonation(for easy starts) of higher cetane, when its cold out.

__________________
1999 E300DT (131,800) 154,000 Black on Black SOLD

2006 CLK 500 coupe Capri Blue on Grey (zoom,zoom)
47,000mi

04 VW TDI Passat 80,000mi
(Techno)

How to eliminate oil dependency through market-driven approaches.
“We could cut oil use in half by 2025, and by 2040, oil use could be zero,”
The Sound of Diesel Speed
Ode to MB

Man, I would love to see Ralph's description in a molecular schematic. Thanks Ralph69220d...that actually made sense to me...damn miracle. Let me se if I have it right CH4 is easy with Carbon surrounded by 4 Hydrogen atoms but when it gets into the long chains, and am I thinking right, that you get C-C-C-C with each Carbon sharing two others and the rest of the bonding is stated top-wise with Hydrogen except at the end points...
H H H H
H C-C-C-C-C>>>
H H H H

And I guess that my next thing is to ask, with relation to octane, is when it's 87% octane and 13% other...is the 13% other...as in heptane...basically junk...or lower on the distillate scale and similar to cetane? which I see as junk on that scale and right near to fuel oil. I guess I'm trying to understand the distillate scale here. Take a gallon of crude oil, distill it into the various grades and you get...?? What. I assume you get a scale of oils from light to heavy. From jet fuel, kerosene, through high octane gasoline...101-87 octane and here I get lost...is there a source for the distillates out there somewhere? I know it ends with tar but the process is interesting and let's face it, it's sort of guiding the price of gas so has a direct impact on all of our lives. I'd like this thread to continue for a while.

__________________
1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown