Howdy, Jukka. Always a pleasure to hear from you.

Howdy, but you probably mix me with Jukka O. Kauppinen?

Undoubtably Sorry about that. If its any help, I confused you with a great
guy.

some G-6s were preferred over G-10s and Ks, if the former were
considered to be of better manufacture.

As an dogfighter most powerful, lightest and reliable engine would be
preferred
option if flight characteristics otherwise doesn't decline.

The greater speed of the later, more powerful models was often gained at the
expense of a piston rod flying out the hood at bad moments. Apparently,
blowing an engine in the Emil took real effort - by the time you got to a G-14
or K, the engine was likely to blow up after even a few moments at boost.
Heard that from several different pilots - two of them blew up their motors
under identical circumstances; one made a deadstick landing from 9,000 m (at
night!), the other dumped his into a lake outside Berlin. The screws were so
eager to hang him for the loss of a brand new G-14 that they went to the
trouble of fishing the 109 out of the lake - when the damage was obviously due
to defects in the blower, they let the pilot off the hook.

Did engine upgrades happen in field also in E-, G- and K-series Me-109's and
was there a preferred engine/blower combo?

Field upgrades - Usually not, as far as I know. Everyone preferred the
AS motors once they became available.

I have read that DB's (and alla others) engines quality diminish all the
time,
estimated work hours dropped hundreds of hours to some dozen hours.

Absolutely. I have a complaint letter from an NJG 11 Staffelkapitan to the
wing, gritching about engine life being ~15 hours before replacement (dated
March 45) - granted, by that time, the pilots were running scared and boost was
being selected a lot more often than the manufacturer intended.

Thats why aces wanted to stay "old" models and engines?

That probably had a hand in it, plus wing loading got so bad the later models
were becoming real pigs. A good G-2 or G-5, sent back to the factory and
returned as a later model was almost guaranteed to come back as a handling
nightmare.

v/r
Gordon
====(A+C====
USN SAR

An LZ is a place you want to land, not stay.