So having reviewed the technical paper that the pictures came from, with a learned collogue...
As stated in the paper, the replacement piston was made from 2000 series Aluminium - great for light weight, high strength (i.e. aircraft structural grade), but the copper content also makes it high expansion - not a great thing for something subjected to heat while trying to maintain a close fit... Add in the total lack of wear resistance from the minimal silicon content and, erm yeah... 2 hours gentle running was about as much as you could expect
Today’s lesson is that just because you think that its easy to make a new part by measuring the old one, its really not that simple if you do not use the original materials and processes...
A wise old engineer once taught me that they were common on engines for that era, but really were not needed and fell out of favour as time moved on.
