Two thoughts....
1) Jimmy has already covered the thermodynamic theory of why you can't get over 122 psi so I won't do it again. I will say, however, that HGDT's model is pretty simple: I ignore chemistry changes (they're a second order effect when you're talking about air... 80% of your mixture is inert!). I then just magically assume that the air increases to XXXX degrees (I'd have to look up the exact number... suffice to say: stoichiometric flame temp). What does this do to your pressure? That's a high school level physics problem. The only problem is that it assumes that the combustion is instantaneous. It's not, of course. Thus, when I say that my combustion model is crude, what I am discussing is my flame propogation model. There are simply too many variables in the real world to do it right with anythen less than a hydracode. So I make some other assumptions (there are threads discussing what I did if you use the search functions).
2) You state/ask.....
jitup wrote:what type of a meter would you use to find this, I am thinking that you would have to have an expensive electronic pressure sensor hooked up to a computer to monitor the whole event. Do these sensors even exist?
As a matter of fact, yes, such gages exist and I've got a couple on order as we speak. They aren't cheap, of course. I'll be honest and say that I'm not 100% sure what gages I have on order as I've a guy who works for me who specializes in such knowledge and I simply told him what I was trying to do and he took it from there (I do know they're kulites (
http://www.kulite.com), however. Cost? IIRC, he said he would be spending about $3k on pressure gages.).
My point: Give me a year and I'll be able to definatively answer the question you ask as I will be doing some tests very similar to what Jimmy has done but on a larger scale and with a few million dollars worth of instrumentation at my disposal.
Note: The above is NOT meant to poo-poo Jimmy in any way shape or form. What he did is flat out amazing (especially given his budget!). I just happen to be in a position to throw some significant resources at the problem.
edit: I've no idea if this is what I'm getting, but here is a gage that would do the job.... Design application is measureing the pressure inside an internal combustion engine's combustion chamber (
http://www.kulite.com/pdfs/pdf_Data_She ... CS-190.pdf ). edit again: Well... almost. I see that it's range is a bit high, but it proves my point about such gages existing (the hybrid folks would love that gage though!).
