Andy RR: No mention of weight comparison. I suspect that with an iron block and eight steel pistons, it's not going to be a pretty number.
Apparently the iron block isn't heavier according to their blurb.
EPS | Reliability, Safety & Durability
The Graflight V-8 engine derives its name from this key component. CGI is an advanced material that offers extraordinary strength and fatigue resistance, allowing CGI blocks to be made lower weight than equivalent strength aluminum blocks. It was first patented by a German scientist in 1965, but in 2008 an American engineer, Dr. Steve Dawson, first wrote about using CGI in modern diesel engine cylinder blocks and heads. EPS CEO Michael Fuchs was among the first to employ CGI in the automotive field in America. It has since set the standard in the industry because its high tensile strength provides extraordinary durability. Aluminum aviation crankcases often crack from fatigue – a common point of failure in GA airplane engines. But the Graflight V-8 block offers incomparable durability, and will be able to serve far longer between maintenance overhauls as a result.