The DB 604C was a 3,500 hp 24-cylinder injection X-engine. After production began, the entire DB-604 program was cancelled on 4th September, 1942. Put a 3,500 hp engine into a German fighter aircraft, have them flying by late 1943, and things get interesting. Bolt the DB-604C on the He-177 and that ends all the problems.
The 604A/B was making 2,660 hp at best (not 3,500 hp). The 604C had barely been tested, an I can't find a reliable reference to any hp figure (3,500 hp or otherwise). You can't just wave your hand and magic a new engine through testing and development. Particularly not a 46.6 L X configuration, whether its making 2,500 hp or 3,500 hp.
While the engine was similar to the 610 and 606, there was a reason that the Luftwaffe persisted with these engines in the He 177, even with their reliability concerns. The 604 simply wasn't ready to go into production. One five 604s had been made by 1941.
Most aero engines took 4-5 years from initial testing to reliable, front-line running. Even then, even the best of them were temperamental beasts (the Sabre II and BMW 801 spring to mind immediately).
Don't like the 604C? Build the DB 610A-B, a 3000 hp engine or the BMW 802, a 2,800 hp 18-cylinder radial with exhaust gas turbocharger, or the DB-628 a 1,600 hp engine with a two-stage supercharger or the DB 623, a 2,300 hp high altitude engine.
I don't know where you are getting these engine ratings, they don't tend to coincide with the data I'm privy to.
The DB 610 only made 3,000 PS (2960 hp) well into 1944. Prior to this, it was rated at 2,450 PS. The engine had massive cooling problems at this output, and was rarely pushed above 2,500 PS.
The 802 was only cleared for 2,400-2,600 PS on bench tests. There was no flight testing of the engine, due to a singular lack of reliability. I cannot locate a reference to 2,800 hp, unless you are referring to the twin turbocharged private development, the P.8011, which again, never left the testing room.
The 628 again, only cleared for 1,490 PS before it was abandoned, in early 1944.
The DB 623 DID make 2,300 PS (2,270 hp) but DB basically gave up on the engine in mid 1942, and terminated the programme in the beginning of 1943.
Put the Jumo, BMW, DB, Heinkel and Walter engine engineers into a room and tell them, "You have a shockingly short amount of time to cooperate on getting a new powerful water-cooled inline, radial and jet engine perfected and into production. No more company secrets, no more proprietary data, no more competition instead of cooperation, because in about two months, we start killing you and your families.
In a very short period of time, all these engine development and production troubles would have been a thing of the past.
Speaking as a Time Machine Consultant to Adolf Hitler, "You're an insane nutjob dictator and it's time you start acting like it. Start randomly killing some of your own weapons development and production people, because DEATH is a wonderful motivator."
Again with the killing of the designers thing…
Here's an idea. Instead of threatening major industrial players with death, appoint a single individual in charge of overall aircraft engine production. Have them concentrate talent into 6-8 major industrial engine efforts, and let all other projects go by the wayside.
Give them power to directly intervene in production and design decisions, with an eye to getting workable designs into aircraft, rather than very powerful but unreliable engines running on test benches.
Folks, in these threads we are Time Machine Consultants working for Adolf Hitler and the Nazi. I say we stop accepting excuses and do whatever it takes to find some solutions. Whatever it takes. The only thing we all agree on is building the Bf-109Z. But putting more 20mm and 30mm on the target still eludes us, we still don't have a high velocity, high RoF 20mm and 30mm cannon.
Bronc
Actually, I tend to think that the 109Z was a stupid idea, and the Germans would of been better off with a dedicated zerstroyer with all the bugs worked out, rather than that cobbled together monstrosity.
The Germans had essentially the best aerial cannon of the war, particularly anything above 20 mm. Your 'high velocity' (what 750 m/sec isn't fast enough?) 20 mm is going to be longer and heavier (and possibly bulkier) than the MG151/20, so is it worth the sacrifice?