Mostly what I’m trying to figure out is what dictated the differences in frontal area between a Hornet nacelle and a Mosquito nacelle, and if the 130 engines were truly unique specimens, (ie, few if any parts would interchange with other members of the 100 family, or earlier 2 stage Merlins). I don’t think that the engine frontal area is much different aside from accessory arrangements (supercharger intake mainly, and the Hornet’s intercooler being integrated with the radiator/oil cooler matrix)

Also, I’ve been wondering why the area between the spinner and exhaust outlets on the Hornet vs the Mosquito seems to be longer. Of course, it doesn’t help that I haven’t been able to see any HQ photos of a Hornet’s engine bay recently (DC’s Hornet/Sea Hornet book is part of my collection, and is buried in a plastic tote with all other kinds of collectable stuff in it’s original box). But, and this is a rough estimate, it seems that the armored spinner back plates on the Sea Hornet assembly line stills on British Pathe and photos of the final build of KA114 (the only currently fully airworthy Mosquito), the back plate diameter looks about the same, and surface area seems similar, along with those that I’ve seen of the back plates fitted to Packard V-1650 powered Mustangs.