Hi Phil, Will be interested in the result, Mike was quite right about the oxygen content it is 23% if we want to be right with the facts. The problem with engines is that Oxy is a bit heavy and a slow mover so does tend to get left behind plus the fact that you dont get a complete burn so we always used to work on 14 / 17% when setting up the amount of fuel to use. I can see that general facts are going to be jumped on so will have to whatch my P and Qs Regards Frank