Merlin XX Merlin X with Stanley Hooker re-designed supercharger incorporating re-designed inlet and improved guide vanes on impeller with revised blower gear ratios; 8:15:1 for low gear, 9:49:1 for high gear.
Merlin XX Merlin X med Stanley Hooker re-designet kompressor med re-designet indsugning, forbedrede ledeskovle på impelleren og ændret gearing; 8:15:1 for lavt gear, 9:49:1 for højt gear.