04.04.2009, 18:58
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.
edit.
I've got some archival documentation on production motors for Daimler Benz. Both the ASB and ASC are listed as in production during 1945 and engine details are listed. The ASB could use either C3 or B4 fuel, with B4 fuel MW50 was used with sondernotleistung at 1.8ata. The ASC used C3/MW50 at 1.98ata in the production motors. No restriction for this setting is given. These details are the same of course for the DB/DC engines listed in production during 1944.
The ASM motor documentation appears to suggest some engine damage issues with the C3/MW50 adaptation of the 605AS and that sondernotleistung should not be engaged under 1.4km. I've read about the piston damage issues elsewhere, but the 2min restriction for MW50 use at sondernotleistung for the ASM (and AM) motor I've actually taken from Oleg's reference to researched data, though I'm sure I could also find these documents as readily available, just a matter of tracking them down.
These restrictions do not apply to the D series 605 however, which had no issues firstly with using B4 fuel with MW50 for improved outputs over 605A series using C3/MW50, and up to 1.98ata using the latter fuel combination. It is a common notation the 605D was further developed for 1.98ata specifically (but I fully understand your reservations about actual service fitment of this version).
Nevertheless the question would then remain, where did all the 605DC and ASC engines which were definitely produced in 1944-45 go? Surely they did not simply lay around factory floors when even 605A-1 were being tossed into G-14 airframes as necessity dictated.
And there is no listed restriction on 1.98ata I can find for the DC/ASC.
My question to you would be, what are your sources there was any issue with 1.98ata for D series motors?
edit #2.
forgive me, I'm a little tired and drinking. The confusion appears to be in the belief that the ASB and ASC are "AS series" motors, which is not exactly true. The AS is an A series. The ASB/ASC are D series.
This should answer your question.
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.
edit.
I've got some archival documentation on production motors for Daimler Benz. Both the ASB and ASC are listed as in production during 1945 and engine details are listed. The ASB could use either C3 or B4 fuel, with B4 fuel MW50 was used with sondernotleistung at 1.8ata. The ASC used C3/MW50 at 1.98ata in the production motors. No restriction for this setting is given. These details are the same of course for the DB/DC engines listed in production during 1944.
The ASM motor documentation appears to suggest some engine damage issues with the C3/MW50 adaptation of the 605AS and that sondernotleistung should not be engaged under 1.4km. I've read about the piston damage issues elsewhere, but the 2min restriction for MW50 use at sondernotleistung for the ASM (and AM) motor I've actually taken from Oleg's reference to researched data, though I'm sure I could also find these documents as readily available, just a matter of tracking them down.
These restrictions do not apply to the D series 605 however, which had no issues firstly with using B4 fuel with MW50 for improved outputs over 605A series using C3/MW50, and up to 1.98ata using the latter fuel combination. It is a common notation the 605D was further developed for 1.98ata specifically (but I fully understand your reservations about actual service fitment of this version).
Nevertheless the question would then remain, where did all the 605DC and ASC engines which were definitely produced in 1944-45 go? Surely they did not simply lay around factory floors when even 605A-1 were being tossed into G-14 airframes as necessity dictated.
And there is no listed restriction on 1.98ata I can find for the DC/ASC.
My question to you would be, what are your sources there was any issue with 1.98ata for D series motors?
edit #2.
forgive me, I'm a little tired and drinking. The confusion appears to be in the belief that the ASB and ASC are "AS series" motors, which is not exactly true. The AS is an A series. The ASB/ASC are D series.
This should answer your question.