John,

Regarding my usage of the word vacuum - I must apologise if I'm not anal enough, but my meaning is generally "less than atmospheric pressure". I generally attempt to maintain strict definitions but I am a Gen Y so I have to follow the stereotype sometimes.

I agree that the majority of the losses will be from the various frictions. My example with excel gives you a rough idea - 2.5kW is in no way enough to slow down a car. My posts have simply been to express my ideas about the power losses through the compression event.

When I've had a vacuum gauge attached to my car, cruising down big hill in top gear results in the gauge nearly hitting the maximum negative measure (absolute vacuum on this particular dial). Assuming that the gauge is inaccurate and badly calibrated, let's say that the actual manifold pressure is around 1.6psi above vacuum. Idle pressure is not too far above this so I don't see it as a stretch of the imagination. Once compressed by the cylinder in my example 9.2:1 CR engine the end result is [an unexplainably coincidental] 1 atmosphere - the same pressure it was as it was before entering the throttlebody. There are a few avenues for it to gain heat energy before entering the cylinder to be compressed but I think that exceeding the temperature of the water jacket is a stretch. Your experiment does not falsify my reasonings thus far which is always a good thing for an argument

Regarding excel: It is a wonderful tool. I'm a numbers and maths guy at the core and have been since I learned to program in primary school. Roughly banging out a few equations gives you a real insight into what's going on. The numbers don't even need to be close to accurate - the truth lies in the order of magnitude of the result. I could have any of my guessed factors out by a factor of 5, or 0.2 and the result is still meaningful since it shows an approximate relationship between the input variables and the output, which through text discussion alone, gives you no quantifiable and predictible connection, only conceptual. Approximations are only a problem if you can't also see a relationship between input error and output error. I felt at peace with the approximations I've made, a distinct contrast to some of the things I was taught in most electrical circuits university subjects which usually left me shocked thinking "how does the world function with engineers approximating like this". Thank the gods of engineering for safety factors :lol:

And finally regarding the existence of the temperature of vacuum. The best example is the cosmic background radiation. Inside our observable universe at least, there is no such thing as zero energy space - every volume contains a torrent of photons whizzing around. Add up the energy of the photons and you get a temperature. An irrelevant point when talking about the temperatures of the compression event though so I'll leave it at that and call it a night