Fleming Technical - Excellence in Formulation

Diesel Plus - The science behind the product

Better cold starting
Smoother running
Reduced engine noise
Increased power
Improved fuel economy
Reduced carbon formation inside the engine
Improved exhaust emissions

Can a fuel improver do all of this?

Yes it can. Diesel Plus does this, NOT by increasing the energy value of the fuel, but simply by correcting the many inefficiencies which poorer quality diesel fuels suffer from. The information which follows is necessarily a little technical. It does, however, explain the subtle ways in which Diesel Plus can improve your diesel motoring experience.

How does Diesel Plus work?

Diesel Plus uses a specialised organic nitrate to increase the cetane rating of diesel fuel. When dispersed in the fuel, the nitrate acts like millions of tiny sparking plugs which help to initiate combustion smoothly throughout the fuel charge. The cetane rating is akin to the octane rating of petrol - it describes the fuel's ignition quality. A 1 in 500 dilution of Diesel Plus can increase the cetane rating of diesel fuel by up to 5 numbers. An improved cetane rating allows the engine to use the fuel as intended, with a smooth powerful burn and minimum noise. The graph opposite compares the combustion of untreated (low cetane) and treated (high cetane) diesel fuel.

Click on the graph to see a larger version

Fuel is injected into the engine ahead of top dead centre (TDC) to allow the fuel time to be heated and for ignition to begin. This time allowance is called the ignition delay and is crucial to the correct operation of the engine. With the treated fuel (red), ignition begins correctly just after TDC, resulting in a smooth, symmetrical burn. The untreated fuel (blue) is much more difficult to ignite, resulting in an extended ignition delay. When it does finally ignite, the ignition is edge-initiated so that a combustion travels through the fuel charge, creating a shock wave and pressure pulse, peaking at about 150psi higher than treated fuel. This pressure rise indicates explosive combustion or detonation - the cause of the loud knocking often heard from high mileage diesel engines.

Coking prevention

Another valuable benefit of cetane improvement is the elimination of coke deposits in the engine. Coke glows red-hot inside an engine and can cause premature ignition of the fuel charge before TDC, - the resulting pressure increase works against engine rotation (reducing power), while wasting fuel which should be usefully employed. The following electron microscope pictures show how treated diesel fuel protects an injector against coke formation.

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