Attention: TDR Forum Junkies 
cerberusiam said:
Yes this is true that the compression ratio is the relationship of the volume of a cylinder with a piston at Bottom Dead Center (BDC) to the same cylinder at Top dead center (TDC). But there are some things you may not realize. that theory only applys to a given space (combustion chamber in this instance) that does not contain matter (matter = scientific word for an object such as air or water or salt or you get the idea) that is not compressable.
What some are confused about is in science class they were taught you cannot compress water. So what they are saying it is just takes up space. This is very true to you newbies, but you have to understand that a water injection system is spraying water and methanol mixed as a homogenous mixture. Methanol evaporates easy if I can remember correctly (not sure though go look it up, I just cant remember from research early last week also has quite an interesting history on the encylopedia website I researched it on), But you are fine spraying (not flooding) that cold mixture into a 300 degree fast moving are stream that is under pressure it will tend to mix with the other air molecules going into the engine. Yes you newbies are very correct that water raise compression but its a mixture of methanol and water and they are mixed so thoughly and almost evaporated if not evaporated inside the combustion chamber before the diesel injectors spray and ignite the charge. Yes they molecules of water meth that didn't evaporate raise compression but only on a extreme end of a scientific decimal range. not something that will make a difference.
Also the guy I quoted is a very smart individual but I must also tell you all out there that there is more that the difference between BDC volume and TDC volume that makes up the compression ratio. The shape and size of every dimension in the NASCAR engine building world changes the compression. for instance on a gas engine if you have two cylinders both the same volume except one has flat piston and the other has a dished piston but the volume of the cylinder the same the one with the dished piston has high compression. The purpose of the hemi-sperical shaped combustion chamber was to increase compression with less stroke on the hemi engines. I know this isn't a Mopar gas engine website but so many people understand gas much more than diesels becuase diesels are a mystery to them. Well they are not all that different except the theorys of igniting the combustable mixture and the parts needed to make it happen and withstand it. Some of the top drag racers in the diesel world will tell you the same cuz they are converts from the gasoline world
Oo. I thought there for a 1/2 a second (cause thats all it took) i was gonna go through the back glass holdin on to the stacks with my feet flyin in the wind! 
