A Hemi has a 4.840" bore spacing where a BBF has a 4.900".
My guess, and this is just a guess, is that JFR/Ford is developing a block and head combination that will have "brand identity" as opposed to any huge revolutionary designs. There is always room for improvement to the fuel motors (strength, maintenance/servicablity, etc.) and with today's CAD and CNC offerings one would think you could indeed improve on the Hemi design. Ture, after 30+ years you might say that anything that could be done has been done. But, if you could start with a clean sheet and only work within the given parameters, a better mousetrap just might be invented. If nothing else, though, JFR/Ford will have a motor with a disctinctly different look to it (valve cover configuration, mag placement, general exterior shape) while maintaining the "spec" internal dimensions.
The "spec" parameters refer to crankshaft centerline vs. bore centerline, crankshaft centerline vs. camshaft centerline, valve angles/attitudes, bore spacing, deck height, deck angle, and a few other minor internal dimensions. Things like head bolt pattern, external block and cylinder head shapes, webbing, gear drives, etc., etc. are all open to design changes.
It would be fairly easy to develop a unique valve cover for the Hemi to make it look simlar to the Boss 429 style...but when you have the resources that Ford and JRF employ why not try and build a new and potentially better system? While we're on the subject...what's keeping GM and Toyota from doing this very same thing with Snake and Kallita, respectively? Talk about a built-in marketing tool!
