[brentce]

Hi brentce
I did some research on this a while back but my most immediate reference simply cites Mercedes Benz AG archives in Germany (this particular page is simply in a handy spot on my computer for quick reference), though since you bring it up I might look some other primary source documentation up, I'm sure I've seen some extrapolating 1.98ata.
I've been more involved with Fw-190/Ta-152 research lately.
According to archives the 605DB and DC were definitely fitted to the K-4 in service. War records going much into 1945 are extremely sporadic, the archives suggest some ASC fitments are likely during 1945, whilst similarly they are also "likely" for the G-14/AS (both ASB and ASC motors). The difficulty is that these motors were not available until 1945, when record keeping sort of got tossed out the window. Certainly some pilot reports claim that whilst some G-14 had shocking build quality and performance, some individual examples had performance equivalent to the G-10 or K-4 during 1945.
I'll get back to you.

I will add however to recall what the AS motor describes. The basic engine was a 605A fitted with the 603 supercharger for increased rated altitude and full throttle height. Both these engines experienced great difficulty when run at sondernotleistung due to problems with the pistons (they burned and holed). Plus service life and general serviceability was dramatically reduced under these conditions.
The ASB and ASC motors of 1945 appear to be the same 603 supercharger adaptation to the DB and DC basic engine. The DC is I'm certain rated for 1.98ata for the full 5min start und notleistung and sondernotleistung using C3 fuel and this was used in service. Hence I see no reason for the ASC to be any different.
The ASB and ASC are not 605A base motors, they're 605D series.

Hey Vanir

Thanks for the quick response! I believe your mistaken that DB605ASC is a DB605D-based motor. I'm almost certain that it's a DB605A with the same larger DB603 supercharger as the DB605AS, ASM and ASB, but configured for C3 fuel. These being analogues to the DB605DM, DB and DC. It's my understanding that the 605AS's were of similar power ratings as the 605D but less robust.

While the 605DC was intended to be cleared for 1.98 ata we still haven't seen clear evidence that it was, just that it continued to be tested into 1945. I haven't seen any evidence that the 605ASC was cleared for operations at 1.98. In fact it doesn't appear that there was any service testing of this configuration. I'm sure there's plenty of documentation in the MB/DB archives for various potential 605A and D configurations, but operational clearance and use by the concerned air force is where the rubber meets the road in the historical sense.

Brent