Merlin vs DB 605

[Neto]

People this question make my head blow... someone can tell me what is the best engine ?? I think that the DB with fuel injection is better but i like that someone give me more arguments.

[CPWN]

Merlin is better. DB605 was larger and confused by low octane fuel. So DB605 needs MW50 to increase power at low/medium altitude.

[AL Schlageter]

The DB605 could use C3 fuel which had a pn number approaching 140.

Merlins, whether the American or British model, used injection carbs. This was fuel injection but not direct FI as on the DBs.

[Neto]

Originally Posted by AL Schlageter

The DB605 could use C3 fuel which had a pn number approaching 140.

Merlins, whether the American or British model, used injection carbs. This was fuel injection but not direct FI as on the DBs.

Injection carbs ?? lol this is new, or you invented?. I heard that the only solution that merlin haves to solve the "negative G" is the "Miss Shilling's orifice" tha uses a diaphragm to control the flux of petrol. this is efective in negative g dives, but only for few time.

[AL Schlageter]

It was not a diaphragm. Do some more research.

You need to look at the R-R S.U. fuel injection pump and the Bendix Stromberg injection carburetor.

[mad_max]

As I posted in another thread in the Engine forum.

There is so many variables that there is not a single easy answer. As for the 1650 (esp. in
the B model) it depends if it the -3 or the -7 series. The -3 was the "high" altitude engine
and the -7 was the "medium" altitude engine. They would have different flight envelopes.

Are the performance numbers your looking at using 100, 100-130 or 100-150 PN fuels
for the merlin and B4 or C3 for the 605 series?

Those are some things you need to specify before a comparision can start.

Of course what can be said now is the engines are two different breeds. The 1650 uses
a 2 stage 2 speed supercharger that is gear driven. The 605AS/D uses the enlarged
single stage supercharger from the 603 combined with a fluid coupling. Both have their
advantages and disavantages.

The 1650 uses a lower compression ratio with higher boost pressures whereas the 605
uses higher compression ratios with lower boost ratios. As I understand the theory is
both had relatively the same combustion chamber pressures, but I'm not an engine man.

The 605 has direct fuel injection into the cylinders...still the best way to get efficiency, plus
with injection the fuel is atomized by pressure; thus lower volatile fuels can be used.
The 1650 use what is call an injection carburator and the fuel is helped with atomization by
going through the supercharger.

The 1650 is a 27.02 liter engine and the 605 is 35.7 liters.

That is the beginnings to an answer, but really they were developed with the materials
and fuels available or told to use. DB was required to get the maximum performance
using B4 fuels.

I don't think there is a clear winner or loser here.

[Neto]

Originally Posted by mad_max

I don't think there is a clear winner or loser here.

Yes i conform with your idea it is dificult comparete this two engines,both 2 were fenomenal.

[FLYBOYJ]

Originally Posted by Neto

Injection carbs ?? lol this is new, or you invented?.

Apparently dumber than first thought!