Now we are talking about engines and speed in the G10, I thought it would be interesting to look at the G6 too.
Looking at the figures for the AH aircrafts one notice that the 109G2 is listed with a max speed of ~405mph but the G6 with just ~390mph (also what I reach in tests). To my knowledge the G2 used the DB605A engine, and this was also the first engine to be used in the G6, but it had later other installed.
With that topspeed it is for sure this engine that is being used in AH's G6 is the DB605A tho. However I would like to repost a message I took from another board:
S! all,
I haven't posted much in the last couple of weeks because I've been busy doing as much research as I could on the 109G-6. I decided to do this after reading a post from Bury about Tempest pilot, Roland Beamont, who had claimed in his book "Tempest Over Europe", that he had flown a G-6 at 430 mph. Given the power outputs of the Daimler Benz engines of the 1943 - 1945 period, this figure struck me as being much more realistic than the 386 mph claimed by Eric Brown in "Wings of the Luftwaffe".
The problem with finding correct data for the G-6, is that it was in production for well over a year and there were so many changes in engines, specialized production variants and field conversions. It seems that the authors of books on aircraft aren't a very technically minded lot, and most were totally confused by the sheer variety of G-6 sub-types. The vast majority of them have just reprinted Eric Brown's performance figures, even when they are talking about a standard 'vanilla' G-6, or a completely different variant alltogether.
As it turns out, I think Eric Brown and Roland Beamont were both right. However, they were describing completely different versions of the G-6. While Eric Brown was talking about an early model G-6/R6 sub-type, Roland Beamont was talking about a late model standard 109G-6.
I've been looking through many books at my State Library and in my own collection. I've also checked out every website on the net that contains 109G-6 data. The performance figures are almost always the same, apart from a few exceptions. Very few sources correctly identify the aircraft they are referring to as a 109G-6/R6, even though most report the extra two cannon gondolas.
Where all these sources really diverge though, is in the listing of the type of engine fitted. They include DB605 A, DB605 AS, DB605 AM, DB605 ASM, DB605 ASB, DB605 ASD and DB605 D. However, if power figures are included, it's usually 1,475 hp which is the take-off output for a DB605 A.
Looking at these sources, you would think that the top speed of a G-6 was 386 mph, no matter what variant/version it was and what kind of engine/weapons configuration it had. Of course, this is complete nonsense!
Microprose has saddled us with the worst possible choice for the 109G-6. The 109G-6 in EAW is actually a 109G-6/R6. The R6 was a field conversion kit (Rüstsatz) adding a pair of 330 lb, 20mm cannon pods beneath the wings. This is the slowest, heaviest and least manoeuvrable variant of the G-6, with firepower being it's only real virtue.
Er... well it would be a virtue if we actually got the R6's under-wing cannons. 
According to Adolf Galland, the R6 equipped 109's were only effective against the B-17 formations in the absence of enemy fighters. When the USAAF fighter escorts began arriving in force, the R6 kits had to be removed. Here's a quote by Galland on the R6; "These 'gondolas' or 'bath tubs', as we called them, naturally affected the performance of the plane badly, for an aircraft defaced in this way was as good as useless for fighter combat." Yep, that's our baby!
To cap it all off, the 109G-6 in EAW is fitted with the least powerful version of the DB605 engine, namely an early DB605 A. This engine was introduced at the beginning of the 109G series in mid 1942. Once the Luftwaffe had met the B17 formations in late 1942, it became immediately obvious that the DB605 A engines did not have enough high-altitude performance, so they were quickly superseded by the DB605 AS. This engine was fitted with a bigger supercharger and gave the G-6 a maximum speed of 412 mph @ 16,400 ft.
I'm fairly sure that DB605 A engines could not be converted to DB605 AS specs because the compression ratio was too high. However, Me109 production numbers nearly doubled in the final quater of 1942 so it's probaly safe to say that the DB605 AS would have been the dominant engine on the Western Front by the start of 1943.
By May of 1943, the range of the P-47C had been doubled with the addition of drop tanks, allowing them to take over escort duties from the P-38H, therefore the B-17 formations could operate at much higher altitudes than before.
This had been anticipated however, with the development of MW50 injection. DB605 AS engines were converted to DB605 ASB (87 Octane fuel) or DB605 ASC (96 Octane fuel), by fitting them with MW50 injection systems. An MW50 equipped G-6 could achieve 425 mph @ 24,000 ft.
Sometime during this period (early to mid 1943), the DB605 AM and DB605 ASM engines became the standard issue on the G-6 production lines. These engines had lower compression ratios and higher supercharger boost pressure and were designed for even higher altitudes with a WEP of 1,800 hp using MW50. At this point, I think we can assume that the DB605 A and DB605 AS engines had become obsolete on the Western Front and were subsequently fitted to 'export' versions of the 109G-6 only.
A lot of people have wondered why the Me109 wasn't retired by this stage, as it was already showing it's age compared to the Fw190A. According to Adolf Galland, it was because the Fw190A's (pre A8) performance fell off rapidly above 21,000 ft, making it much less capable than the G-6 for fighting the P-47 escorts at high altitudes.
The last of the production engines fitted to the 109G-6 was the DB605 D. I believe this was in late 1943 or early 1944, but I'm not sure exactly. Like the DB605 AM and DB605 ASM engines, the DB605 D also had a WEP of 1,800 hp using MW50. However, it could use a lower octane fuel than it's predecessors to achieve this output. The DB605 D was also used in the 109G-10 which had a maximum speed of 429 mph to 431 mph @ 24,280 ft and 342 mph @ sea level.
So basically, for the two most important years of the war (1943/44), we are supposed to fly this obsolete, overweight, underpowered 109G6/R6, with a couple of 330 lb lead weights hanging under the wings in place of the extra 20mm cannons.
Anyway, that's my two cents worth on the Me109G-6,
Derek.
Interesting stuff, eh? Could it be that this is true? Even tho we may be equipeed with the first version of G6 with the DB605A it gives an good answer to the strange drop in speed from the G2 to the G6.
G6 was fitted with the 13mm instead of the 7.92mm of the G2. How big is the weight difference?
Giving away 15mph for this seems awful much.
Comments?
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Ltn. Snefens
RO,
Lentolaivue 34
