Scott Bair did the actual test by putting a pressure sensor in a Super Tigre 46 and logging pressure against crank angles (I think this was part of an engineering thesis). Brett Buck took the raw data and converted it into a graph which showed the torque this pressure produced on the crankshaft. This was theoretical torque and actual torque would have been different because of friction losses in the engine but the output curves would have looked the same except lower. The second graph he made was a calculation of the affect this varying torque would have on prop speed at different crank angles and shows how the prop (a wood 12x5) varies in speed by a surprising amount. What I found interesting was the surprising amount of peak torque on an actual firing stroke which of course tends to tighten the prop nut.

OK, after all that blather, I've got the graphs [link=http://www.holdfastmac.com.au/424stroking.html]here[/link] on the web page I do for my local club. Just for interest's sake, I had permission from Brett to put his work on the web page.