[dalola]

FR,
Not that this is really relevant to your question, but rather just FYI. I do prototype engine development here with Honda, and we've been using siamesed cylinders for years now, in mass production applications such as the current V6 Accord, and many other V6's. I believe it was originally developed as motorcycle technology, and eventually worked it's way into automotive applications. You might find some technical data and research materials on the SAI bookstore website, if you are interested in learning more about this design.
~Dave