GregP
Major
"Transport Merlins" refers to the heads, not the blocks. The transport engines were almost all (but not ALL - there WERE the Merlin 102, 102A, and 600 2-stage units) single-stage, 2-speed superchargers, but the heads were made more robust.
So-called transport engines, as far as I know, include the Merlin T24, T24/4, 102 (1st civil 2-stage engine), 500, 501, 502, 600, 600A, 620-624, 626-1, 626-12, 724-1, and 724-1C. Some Merlin 224, 225, and 228s found their way into civil applications, though MOST of the 220 series went to military projects. Perhaps some of the 224 - 228s went civil AFTER military service.
So-called transport engines, as far as I know, include the Merlin T24, T24/4, 102 (1st civil 2-stage engine), 500, 501, 502, 600, 600A, 620-624, 626-1, 626-12, 724-1, and 724-1C. Some Merlin 224, 225, and 228s found their way into civil applications, though MOST of the 220 series went to military projects. Perhaps some of the 224 - 228s went civil AFTER military service.