hello members and guests.
I dont know the reason why the DB 605 AS of the Me 109 G requires the C 3 fuel .There is no more power output and no higher boost.Later the K 4 was satisfied with the B 4 fuel.
Thank you for answer.
Regards,Achi
The 605AS is just an A-1 of the late series (new piston crowns), with a DB-603A blower bolted on and a new gear. It is calibrated for 1.35-4 military and can be calibrated for up to 1.7 overboost but this requires the use of C3 and an induction coolant in the blower *exhaust* which is where Messer mounts theirs.
The type was a derivative of the channel front höhenstaffeln requirement which first produced the G-1 (the Gustav was originally a high alt interceptor version of the Friedrich), itself designed to operate in mixed formations with Fw-190A, which handled low alt intercepts whilst the G-1/GM-1 combination handled high alt.
With the formation of the Reich defence the DB-603 blower was bolted to the 605A-1 for a makeshift interceptor engine with a performance range of 6-9km altitude. The blower loses some efficiency at lower alt so performance is actually reduced under 5000 metres compared with other Gustavs.
It runs on B4. ZD500-B4 kraftstoff
It should be noted that this engine was historically unreliable under this condition, it preferred C3. These engines were sent almost exclusively to Reich defence in early 44 which operated in mixed formations with Antons, their airfields received C3 and might've actually had B4 shortages.
It is perfectly possible any given G-5 or G-6/AS might have run on C3 but they should have a B4 fuel card.
To overboost the AS motor you must have charge coolant and use C3. So the G-14/AS and any earlier model with MW50 kits fitted would also be C3 and have C3 fuel cards until Feb-Mar45 when several G-14/AS got B4 fuel cards and the new ASB motor.
The ASC/ASB motors are just D series updates for höhen staffeln. It's just a DB with a 603 blower, even the oil system is from the DB. The 603 blower actually has better cruise performance than the stock D series blower but the whole thing is a nomenclature issue, the operators of the AS Messers didn't even recognise which model Messer they were, it wasn't like that. Here's how it worked, they got pressurised Messers in 43 with GM-1 and in early 44 they got the new AS motor but Daimler was still having problems cracking 1.5ata with a 1.7 overboost on B4 in the 605 so a handful with MW50 kits and C3 to handle the pressures were delivered but these had a shocking engine life of only a few full throttle sorties before a piston burn-through. Everybody still waited for the D series motor.
In the meantime engine life in interceptor squadron had an even higher attrition rate than combat losses and many more were being created, as G-14/AS updates of the G-6/AS standardised the MW50 kit and 1.7ata overboost (1800PS on the bench and 1500PS at interception height), these all used C3 fuel.
It is well documented the RLM wanted all fighters if possible, to use B4 fuel and it has been noted as simply more realistic too. The D series updates and requirement to run on B4 fuel were added to the 1945 AS motor series production so that some G-14/AS started to receive the ASB motor when they requested a periodic engine replacement. These are almost identical to the DB motor in all specification and build, with the blower as the only change and cruise ratings as the only effect of the difference. It's an update for this very result. In 1945 G-14 were occasionally equal spec to G-10 and K-4 standard.
this ASC(M) ASB(M), DBM, DCM nomenclature is nonesense. All D series production derivatives were designed to use MW50 kits on any fuel. It is not stamped or a designation, it's just DB and DC, the latter just recognition of a factory tune setting change between fuels.
It is only stamped to A-1 and AS series engines destined for fitment in airframes with MW50 kits and C3 fuel cards, the fuel type was changed so they had to be stamped and designated. The ASB/ASC series just drops back to ASB or ASC designation and again both are designed to use MW50 out of the box so there's no need to specify and they don't.
The DB and analoguous ASB could interchangeably use both fuels. But if you changed boost calibration for C3 fuel only, you had to redesignate it. Same engine though.