Hi,
The Cetane Rating has a great bearing on how the engine will run/sound
The reason for this, is The higher the cetane rating, The shorter the delay before combustion initiates.
Combustion does not start immediately, the fuel-whatever the Cetane rating, has to warm up.
On injection, there is a pressure rise phase, during which time the fuel mixes with the air, and vapourises, this leads to greater temperature, and a greater pressure rise untill such time as the fuel ignites.( one reason why there is an advance of so many degrees, to diesel injection)--Direct burning of the fuel does not occur unless the engine is under full load, and only on certain types of motor. ( one reason diesels sometimes sound quieter while accelerating, than while idling!)
The shorter this period of time is, The better, to achieve this you need a high Cetane rating fuel, or a higher temperature air in the combustion chamber.-The lower the cetane rating the longer the delay, and the greater the apparent "Diesel Knock/nailing.
Desmondo and I have been discussing Cetane rating and Biodiesel ( which has a Cetane rating of around 55, and you would be suprised how much quieter the motor will run with it! ) over on the Infopop forum recently, as to how it affects the Injection Timing requirements. For the high Cetane of BioD and SVO, it has been found for the interests of NOx emmissions, that a reduction in Injection advance is needed, of around 2-3 degrees, to in part compensate for the reduction in combustion delay, and hence the peak combustion temperatures, the higher the combustion temperature, the more NOx is created. This is one reason why manufacturers of Gasoline vehicles have tended to lower the compression ratios since the introduction of Emmission Regulations.

Alastair, At The Diesel Combustion Theory Div. SWC.

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Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....