Hi, it's my first time posting in the forum and I want to know if those engines are similar, what pieces differ from each other or if I could swap my f18 for a f20 and would be plug and play. Thanks in advance.
Should be essentially plug and play. The only real differences should be internal to the block. If you want to verify what may be different, use this website to look up diagrams with part numbers. It will be very useful for compare and contrast. https://www.parts-honda.uk/