The P-40 was heavier than the other fighters you list.....
No disagreement there, the P-40 was overweight its whole life, even in the stripped down "Gypsy Rose-Lee" versions.
.....That affected the ceiling. Do not confuse cause and effect......
But the P-40F with the Merlin had far superior altitude performance than the
lighter P-40E, so the Allison engine
is the cause of the resulting effect.
.....Ratings for the V-1710-33 seem to be a bit scattered but include 1090hp at 13,200ft and 1040hp at 14,300ft.
There was some disagreement between Allison and the army over these ratings as the army wanted the Higher HP rating.......
The higher figure seems to relate to a few Flying Tiger P-40Bs which had hand-built engines built from spares. These were closer to the RAF's and Rolls-Royce's practice of "fitting" engines (assembling from carefully matched parts for the best performance), whilst the average Allison that saw USAAC service was assembled to loser, mass-production tolerances. The RAF method was a headache for spares and servicing, but was valued for the extra performance. I'm not saying the Allison was a bad design overall, in fact it was a good and reliable design, but the early variants had a low rated altitude, and the USAAC's fixation with turbocharging meant it never got a good mechanical supercharger until too late.
.....Which Db 601A? The A-0, the A-1 or the Aa?......
Figures are for the DB601A in the Bf109E-3 as tested by the Luftwaffe in May 1940, so representative of E-3s and E-4s at the time in question.
.....we are also discussing what an airplane was 'designed" to do. The D. 520 was on it's 4th version of the Hispano engine when it got to the -49 version. most of the production models were built with the-45 engine which had a critical altitude of 4200 meters (and 920hp at that altitude) earlier prototypes had the -31 engine with a critical altitude of 3250 meters.......
The original argument was that the Allison did not have a rated altitude lower than competitors, whereas my examples show otherwise.
.....Both the P-40 and the P-39 were built with the highest altitude engines the Army could get at the time.....
Not the P-39. The XP-39's mid-engined design gave space for the turbocharged Allison V-1710-17 , it was NACA that dumped the turbo, killing altitude performance, in the quest for level speed at lower altitudes. A turbocharged P-39 would probably have had some of the issues the P-38 had in the ETO, but they could have been sorted with the same amount of effort as was thrown at the mediocre P-40. As it was, the P-39 was developed into the P-63, which was far superior to any frontline P-40.