Thursday, February 28, 2008

Gas or Diesel?

Just a quick little post more for more a mental note for me than anything..ya know how it goes with memory and getting older..
Anyhow, I was having a conversation with my classmate at Permaculture about VWs and converting them to run on biodeisel or SVO (Straight Vegetable Oil) and the question came up about why the car has be diesel. Well I'm actually not sure the explanation why (tho it has something to do with the necessity of a spark plug in gas engines), but I did find out the reason what the differences are and why gas run cars can't be converted (you lucky diesel car owners, you!). Below is the answer, and also a link to where I got the answer. This site, called PlantDrive, offers a lot of great information about Renewable Oils and Fuels.

Q: Will it (conversion to biodiesel/SVO) work for my gasoline (petrol) car?

No. This is only for diesel engines. Diesels work by compressing air much more than is the case with a gasoline (petrol) engine. This creates high temperatures, and causes a fine mist of injected oil to self-ignite from the heat of compression and combust. The fine mist ("atomized") oils injected into the cylinder just before the piston reaches the top of the compression stroke. There is no spark plug or ignition system in a diesel engine. It is designed to burn a light viscosity oil. Vegetable oils are heavier/thick/more viscous, and so need to be made thinner (less "viscous", lower "viscosity") to work. This is why "biodiesel" (alkyl ester, usually methyl ester) is made ....or, alternatively, why vegetable oil is preheated in our systems.

The chemical process of making biodiesel, or the pre-heating of the vegetable oil both achieve this goal: reduction of viscosity. If that is done, then the engine will run. But never a gasoline engine, only diesels!
...from PlantDrive FAQS
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