Labels:text | screenshot | font | black and white | document OCR: There are several different types of knock, (also called preignition). Knock is a complex subject and will only be discussed briefly here. Knock can be controlled by a combination of: reducing the compression ratio, enriching the fuel-air ratio, insuring that in the design there are no "hot spots" like overheated exhaust values that can cause the fuel to be ignited prematurely, and by raising the fuel "octane" rating. Fuel octane rating is, in my experience, one of the least understood gas engine concepts. The octane rating is actually a measure of how resistant the fuel is to knock. It has nothing to do with the amount of energy contained in the fuel. In fact, higher octane fuels generally have less energy per gallon than low octane fuels, or for that matter, diesel fuel. Octane can be in ...
