cetane value of diesel

Punched 'cetane' into google and this is what I got...

There is no benefit to using a higher cetane number fuel than is specified by the engine's manufacturer. The ASTM Standard Specification for Diesel Fuel Oils (D-975) states, "The cetane number requirements depend on engine design, size, nature of speed and load variations, and on starting and atmospheric conditions. Increase in cetane number over values actually required does not materially improve engine performance. Accordingly, the cetane number specified should be as low as possible to insure maximum fuel availability." This quote underscores the importance of matching engine cetane requirements with fuel cetane number.
Diesel fuels with cetane number lower than minimum engine requirements can cause rough engine operation. They are more difficult to start, especially in cold weather or at high altitudes. They accelerate lube oil sludge formation. Many low cetane fuels increase engine deposits resulting in more smoke, increased exhaust emissions and greater engine wear.
Using fuels which meet engine operating requirements will improve cold starting, reduce smoke during start-up, improve fuel economy, reduce exhaust emissions, improve engine durability and reduce noise and vibration. These engine fuel requirements are published in the operating manual for each specific engine or vehicle.
Overall fuel quality and performance depend on the ratio of parafinic and aromatic hydrocarbons, the presence of sulfur, water, bacteria, and other contaminants, and the fuel's resistance to oxidation. The most important measures of fuel quality include API gravity, heat value (BTU content), distillation range and viscosity. Cleanliness and corrosion resistance are also important. For use in cold weather, cloud point and low temperature filter plugging point must receive serious consideration. Cetane number does not measure any of these characteristics.

Cetane number usually between 30 - 60, that indicate's the ability of the diesel fuel to ignite quickly once it has been injected into the combustion chamber. Thus the higher the number the more easily the fuel will ignite. The lower the number the slower it will ignite and may lead to engine running rough and more polution. But also remember that running higher cetane number fuel that is recommended may not improve the engine's performance due to a number of factors.

What I have wrote has all been said before.

Rossco ( Shell Refinery )

G'day JamieMac,

Cetane is to diesel engines as octane is to petrol engines. The cetane number is a measure of how readily the fuel starts to burn - a fuel with a high cetane rating will burn shortly after it has been injected into the engine or in other words, it has a short ignition delay period. Conversely, fuel with a lower cetane rating has a longer ignition delay period and this causes the condition known as 'diesel knock'.

Although the cetane number of a fuel is assumed to predict it's ignition delay in any diesel engine, the actual cetane number is valid only for the single cylinder engine in which it was measured. The fuel's performance in other engines may differ.

In answer to your question as to whether lower cetane rated fuel could damage engines - long term use would most likely have some effect, but it would be so small as to be negligible. Up here in Darwin our diesel comes in from Singapore and it has a lower cetane rating than Australian produced fuel - I have noticed when I go down south that my Troopy seems to get a new lease of life with the higher cetane fuel.

I hope this has made some sort of sense to you.

Jeff

Yes we have answered your question in short greater engine wear and damage will result. And problem's with slow ignition.

Rossco