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Engine model Power in PS Power in hp Power in kW power at rpm
F,L,M,R 1,340 1,322 986 2,600
DB 601 E
Up to 1,350 PS (992.9 kW; 1,331.5 hp) at sea-level with 2,700 rpm, up to 1,320 PS (970.9 kW; 1,301.9 hp) with 2.700 rpm at 4,800 m (15,700 ft) altitude, B4 fuel
Up to 1,450 PS (1,066.5 kW; 1,430.2 hp) at 2,100 m (6,900 ft) altitude with 2,700 rpm
He-177B with four Jumo 211 engines has about the same total engine power as Lancaster Bomber. I would expect roughly similar performance.
M. Griehl notes 480 km/h for the DB-606 powered He-177. DB-606 was basically a twinned DB-601E. If we assume some loss due to single engines installed in this case, it will be maybe 460-470 km/h? That should be on 'Kampfleistung' (30 min regime, 2 x 2400 PS at 4.9 km).
Heinkel was giving 550 km/h for the DB-610 powered versions (610 would be a twinned 605A), on 'Kampfleistung' (30 min regime, 2 x 2500 PS). The aircraft description sheet does not mention 'Notleistung' (5 min regime, that should be 2 x 2710 PS), probably was not allowed? Griehl notes 520-540 for DB-610 powered versions (4 of them).
The Jumo 211 F will make some 10% less power than the DB-601E, the Heinkel with 4 such engines will be good for maybe 450 km/h? The 211 J is thereabout with the DB-601E in power, though - 1180 PS at 4.9 km on Kampfleistung.
DB 606 A/B
Two DB 601 F or G coupled to work on a single propeller shaft for use in early Heinkel He 177As - 2,700 PS (1,986 kW) at sea level with a mirror-imaged starboard component engine supercharger
DB 610
Two DB 605 "coupled" (geared together) as a "power system" (71.53L / 4364.8in3), to work on a single propeller shaft for use in Heinkel He 177, up to 2950 PS (2,909 hp) for take off, 2788 PS (2,750 hp) at 2,100 m.[6] Mirror-imaged starboard component engine supercharger.
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Why would the 211F give less power than the 601E? They had the same startleistung.
Here are the numbers I found for the 606 and 610:
Startleistung (take off power) is just one narrow (but many times important) part of power curve, and in many more cases than not actually muddles the water re. engine power at altitude.
Supercharger capability and supercharger gearing are main determinants of the power vs. altitude. Some engines sacrificed power at altitude in order to gain more power at low level, or vice versa. We can compare the BMW 801C and R-2800 'A' - BMW has a comparable power at altitude, however the R-2800 is much better at mid and low altitudes.
I especially loath when someone (Wikipedia mostly) just says 'Merlin of 1030 HP', or 'DB-601A of 1175 PS' - just complicates the matters for someone after a real information.
Some data for the DB 610 from Heinkel's brochure on the He-177A-3:
View attachment 288181
The He 277 had four engines of 1,973 HP each for a total of 7892 HP and went 354 mph. I KNOW it didn't get that HP at best altitude, but we have to start somewhere.
If they installed four Jumo 211s of 1322 HP each we have 5288 HP. If I assume a decrease in drag of 10% for the liquid-cooled, smaller engines, we'd get 321 mph on the Jumos. If we go with the four 1450 HP DBs and the same decrease in drag, I get 331 mph. If there was no decrease in dreag, the speeds would drop by some 11 mph or so.
Again, this is a first-order approximation, but I think the real crews would have preferred the 4-engine units to what they got, and if it had proven successful, who knows ... they might have built and deployed more of them.
With the dive bombing requirement omitted, a 4-engine He 177 very well may have been lighter than the existing He 177A models too.The He277 was significantly heavier than the He177 by 5 tons; part of that was the longer wings and fuselage for rebalancing, but was also the extra fuel tanks, as it was the Atlantic Bomber entry by Heinkel, so was different than what the He177B would have been; also the BMW 801 engines were significantly heavier and probably required stronger wings than the Jumos or Daimlers would have. The drag would have been roughly the same, but for the engines as you point out. I think maybe deleting 2-3 tons would be warranted here compared to the four engined He177 due to lighter engines, less fuel tanks, and lighter wings.
With the dive bombing requirement omitted, a 4-engine He 177 very well may have been lighter than the existing He 177A models too.