Engine/Transmission (1998.5 - 2002) Enlighten me about the cetane rating of diesel

[Huff N Puff]

Does any one know about what the cetane rating of diesel fuel,how does it effect the engine,how does it effect power,is 42 cetane rating better than a 40cetane rating. Is it like octane is to gasoline. Any insights into this issue would be appreciated Merv.

 

[David Oxland]

Cetane Number/Cetane Index



Cetane number is a relative measure of the interval between the beginning of injection and autoignition of the fuel. The higher the number, the shorter the delay interval. Fuels with low Cetane Numbers will cause hard starting, rough operation, noise and exhaust smoke. Current commercial fuel cetane requirements may not adequately address these customer satisfaction issues. Generally, diesel engines will operate better on fuels with cetane numbers above 50 compared to fuels with cetane numbers of the national average of approximately 45.



Cetane number may be increased through the refining process or the blending of combustion ignition improving additives by fuel suppliers.



Cetane index is an approximation of fuel ignition quality through measurement of distillation range and specific gravity. It is not affected by the use of combustion improver additives; therefore it produces an indication of the base cetane number of the fuel.



I just pasted this note from some where. Prompt ignition with out delay is especially important in an automotive engine for a couple of reasons;

noise, less knock

smooth running when cold or under light load

better cold starting

With continous running engines under higher loads cetane may not be so much of a factor as already present heat and up to speed(rapid injection) are happening so combustion commencement tends to be promt.

David

 

[illflem]

More than everything you ever wanted to know about diesel

http://www.chevron.com/prodserv/fuels/bulletin/diesel/

 

[Huff N Puff]

Thankyou both

Thankyou David,thankyou illflem

 

[jtisdale]

Give me Fuel, give me Fire, give me that which I desire...

There is a big difference in fuels. There are two stations in town that sell diesel. I have had both tested along with other suppliers from surrounding towns. I have found a 9 cetane difference between the lowest and highest. (42-51) Not all diesel is the same! Buyer beware.

 

[Shovelhead]

Re: Give me Fuel, give me Fire, give me that which I desire...

Originally posted by jtisdale

There is a big difference in fuels. There are two stations in town that sell diesel. I have had both tested along with other suppliers from surrounding towns. I have found a 9 cetane difference between the lowest and highest. (42-51) Not all diesel is the same! Buyer beware.

Since each station's pumps are required to be labeled for cetane content, how much of a variation did you see between what the pump was labeled and what was actually in the tanks?

 

[jtisdale]

6 was the biggest difference. EDIT: (between advertised and test) When I asked the manager about it, he promptly told me my "test" didnt mean anything and is obviously wrong and to buy somewhere else, if I didnt like it. (I didnt test it myself, my pump shop did. ) Our pumps arent labled here. You have to ask.

Of the other stations tested, 4 were as advertised, and 2 were 2-3 cetane lower and this joker was 6 lower than advertised.

 

[TPlasek]

Good Homework!!!



Hard to believe there would be that much a difference.

 

[Shovelhead]

Thanks

I've often wondered about the labeling vs actual on the ratings.

In these parts, the label states "Minimum Cetane Rating".

It's amazing that those "caught with the hand in the cookie jar", like the one station owner, protest the loudest.



I guess just another case of "Buyer Beware"

 

[Un-Hemi]

How and where do you have diesel fuel tested for cetane rating?

 

[jtisdale]

My diesel pump guru did it for me. How, I dont have a clue. He tests most of the fuel in the trucks he works on to keep an updated log for this area.

 

[radar doctor]

Diesel Fuel

I wasn't aware that the C Tane had to be posted. I dont recall seeing anything at the pumps here in Kansas. I wished it were posted. Does anybody have any input on this? Also, Our fuel comes by Pipeline from i think Huston Tx, Is the Ctane put into the pipe line at Huston or is it a additive at the truck Terminal???I'm trying to figure out why our stations aren't standardized?? Help me out here ??????

 

[Shovelhead]

I'm in Virginia, and it's a State requirement for both diesel/cetane and gasoline/octane to be visibly labeled on the pump.