Here is the Bristol Pegasus Aircraft engine in 1:48 scale
Designed by Marc Richman
Here is a 1/48 scale Bristol Pegasus engine I designed for a Supermarine Walrus (it could pass as a Bristol Mercury too) I have provided a pdf and the DXF (created in q-cad)
There are no build instructions, only notes on the plan, if you have questions, let me know
It is released under the Creative Commons Attribution 3.0 Unported License so you can use it however you like, (include it in commercial products if you want) you just need to leave the attribution and license statement intact
If you build one or put it in another design I would love to see pictures!