(Quoted from STUMPS)
"The multifuel engine is a very interesting contraption. It was originally designed by the famous diesel engine company MAN as the MAN Hypercycle Engine, also known as the Whisper Diesel. MAN engineers were attempting to design a compression-ignition (C-I) engine that burned the fuel slowly, and didn't need massive engine parts to withstand the instantaneous ignition found in a conventional C-I engine.
In a conventional C-I engine, the fuel is atomized into a combustion chamber filled with superheated air, and ignites instantly. This results in the very loud "knocking" sound that is characteristic of most C-I diesel engines. Because the entire fuel charge ignites instantly, there are tremendous forces placed on the pistons, rods, bearings, heads, etc.. The usual engineering answer to the need to withstand such forces is to add lots of mass to the parts. That is why conventional diesels run so slowly, and are so big and heavy.
In the MAN cycle engine, the engineers took a different approach. They formed a chamber in the top of the piston that looks much like someone stuck their thumb into a clay piston. When the piston reaches top-dead-center (TDC), the piston's chamber, and the cylinder head, form a closed combustion chamber, with the injector nozzle poking into the top from one side.
The injector nozzle on a MAN Hypercycle engine is different from that used in the usual C-I engine. The nozzle has relatively large holes in it that pass the fuel as a stream, rather than a mist. This stream of fuel doesn't ignite instantly, but rather passes through the super heated air, and sprays onto the walls and bottom of the piston's combustion chamber. The fuel puddled in the bottom of the combustion chamber boils and vaporizes. When the vapors reach the super heated air, they ignite and burn in a relatively slow controlled fashion. The piston's small combustion chamber also keeps liquid fuel away from the cylinder walls, and out of the crankcase.
The LDx-465 engines all have a Fuel Density Compensator (FDC), but that is not what makes a Multi-Fuel engine multi fuel. Hydrocarbon fuels contain differing amounts of energy depending on their chemical characteristics. As a general rule, thinner fuels, such as gasoline, have fewer calories per pound than do thicker fuels such as diesel oil, and waste motor oil. The FDC increases the amount of fuel pumped into the cylinders for thin fuels, and reduces the amount of fuel pumped into the cylinders for thick fuels. It does this by moving the pedal stop, and thus reducing, or increasing how far you can push the pedal based on the thickness of the fuel. A MF engine without the FDC is still multi-fuel, only it will produce less horsepower on gasoline than it will on diesel fuel... much less.... or in terms of smoke, if it is set to smoke on gasoline, it will smoke chunks on diesel, and if it is set to smoke on diesel, it won't be able to get out of its own way when burning gasoline...
-Chuck"
Guess not a lot of people are doing this, though. My buddy has a 55gal drum of used light hyd. oil ready for me to pickup. I guess I better start figuring this out. LOL!
