If you are talking about Lister engines, then it isn't too complex:
First diesel - 9/1 which is also known as the JP or Joint Product engine (after a deal that Lister did with Ruston & Hornsby) Made in 1 to 6 cylinders, went on to the JK and JM versions, most famously known for the searchlight generators in WWII. Block and crankcase in one piece, separate heads.
Second diesel - 5/1 which became known as the 'CS' to many. Produced as the 3/1, 5-1, 6/1, 8/1, 10/2, 12/2, 16/2. There was also a 3-1/2 /1, neither of the smallest HP versions were made into twins, all of the twins were developed from and used the cylinders and heads from the singles.
5/1 and 6/1 are the same engine, 5/1 is 600rpm, 6/1 is 650rpm. 8/1 and 16/2 are much modified versions with no compression change-over, higher speed and ali piston. Block separate from crankcase, exposed pushrods. 3-1 and 3-1/2/1 have unique block, head and piston.
Third diesel - CD and CE, much more modern than the 5/1 but didn't last beyond the late 1940's. 8hp and 16hp at 1000 rpm. Block and cylinder combined, separate head. All enclosed. Gear pump lubrication, double main bearings each side.
Fourth Diesel - FR series, 1 to 6 cylinders, all enclosed, single flywheel, very complex. Block and crankcase combined, totally enclosed. 1200rpm.
Fifth diesel - VA - developed from the 8/1, basically an air-cooled vserion. Same as 5/1 etc., block, head and parts are unique to this engine.
The 8/1, 16/2 and VA do not have the compression change-over valve which all the others have.
All are water-cooled except the VA.
All are plain bearings on the crankshafts with various types of lubrication systems.
The CS and variants have many different flywheel types, from spoked to solid with cut-out, to the Start-O-Matic types. Only the CD and CE have as many variants but they are all solid with cut-outs. The VA has plain or belt grooved flywheels, both types are solid with cut-outs.
Injection equipment is generally CAV, injector nozzles and pumps can be interchanged to a degree on the CS singles and twins, but from the 8/1, 16/2 and the VA have different injectors altogether, but the pump is virtually the same.
That's most of the relevant points.
Pare
