[Chock]

Not so much in the actual construction (although doubtless that too played a part), more a case of the level of skill used in making the components and how they were fitted, as well as some indirect inspirational thinking.

Comparable water-cooled stationary engines in craft such as the SE5a, DH4 and SPAD, i.e the Hispano-Suiza, the Wolseley Python (aka, the British built Hispano-Suiza), the Wolseley Viper and the numerous FIAT and Peugeot engines shoehorned into the DH4, were often beset by problems. This was especially true with the SE5 and SE5a, with the Hispano-Suiza geared-down versions fitted into them being notorious for having badly-tempered gears and similarly dodgy crankshafts, which was something which prompted RAF to try a direct-drive engine. Many of those engines also suffering from general cooling problems which exacerbated the failure of those parts.

It's worth noting that the SE5a was often run with the cowlings removed when in the warmer US climate, specifically to get around cooling issues. By contrast, most German types did not have a closely-cowled engine even when powered by a water cooled engine, a design feature which showed up on the DH9 in comparison to the enclosed engine of the DH4.

That aside, you can learn a lot about production methods of engines simply by looking at the thing, to see how parts have been cast and what revisions have taken place on later iterations. But other things can also occur.

Immediately following the Great War, there was a general feeling that because the DVII had a water cooled engine, and because it was highly regarded as one of the best fighters of the war, that water-cooled engines must be the way to go. It was Frederick Brant Rentschler, who had been the head honcho at Wright Aeronautical who was an advocate of developing an air-cooled radial, but he was flying in the face of that general opinion about the superiority of water-cooled types. Also adding to the problem was the fact that there were literally thousands of spare water-cooled Liberty V-12 engines sat in warehouses in the US waiting to be used, and nobody wanted to admit they were largely obselete, because they had such a poor power to weight ratio.

Rentschler left Wright Aero when they could not be persuaded to build an air cooled radial, and instead teamed up with Pratt and Whitney to make the Wasp Radial, with Wrights later using some of his ideas to make the similarly air-cooled Wright Cyclone. But both of these engines had been born out of studying the water-cooled engines of the DVII and coming to the conclusion of 'why carry water, when you can carry extra payload?' Thus the study of the water-cooled engine led to the development of the air cooled engine, since the goal of Rentschler when creating the Wasp radial, was a one-to-one power to weight ratio, as opposed to the V-12 water-cooled Liberty, which had around half that performance, delivering approximately half a hoesepower for every pound of weight, much of that weight being the cooling system and bulk of the water cooled system jacketing the cylinders and other parts.

The other thing of course is that, as with the Mustang, bf109 and Spitfire etc of WW2, it was the glycol coolant system which left them more vulnerable to combat damage when air-cooled types would not risk the same potential problem.

Al