enginehistory.org

[rinkol]

The SAE paper SP-841 is an account written by Hans List of his life's work on engines. He states that during WWII "we succeeded in increasing the power of the DB603 engine by optimising the intake and exhaust systems. By injecting the fuel with nozzles through the open inlet valves into the cylinder, it was also possible to improve the fuel consumption."

Is there any information as to which versions of the DB 603 had these changes? My understanding is that the DB 603 was, at least to start with, basically an enlarged DB 601E. Both engines were rated to run at 2700 rpm, but the DB 603 had a displacement that was larger by a factor of 1.31. This seems to roughly correspond to the difference in rated power between the DB 601E and DB 603A. The published figures for the specific fuel consumption of both engines are the same (205 g/PSh). The DB 603E is specified for the same specific fuel consumption, though given that the rated power is slightly higher and the supercharger has been redesigned to increase the rated altitude, some improvements would have been needed to keep the specific fuel consumption the same and provide the increased power.

I'm curious about the DB 603N, but information seems very scarce about this version. The continuous power rating was specified at 1930 PS at 2700 rpm, a substantial increase from the maximum ratings of DB 603A and E for the same rpm. Even with C3 fuel, it seems that significant improvements would be needed to achieve this performance. However, as this engine seems to have introduced major changes in the supercharger and general construction, there are obviously many variables involved.

Robert

[szielinski]

Was that a kind of early multipoint fuel injection?
i.e. physically staging the injection further up or down the intake tract depending on induction rate & temperature.

Or did they actually mean squirting fuel right past the valve into the cylinder? (I am assuming it wasn't fuel enough to be liquid at the other side of the cylinder and disturb the boundary layer or oil film).
_________________
“Make everything as simple as possible - but not simpler” – Einstein.

[rinkol]

szielinski


Good questions. i was hoping someone could shed some light on this subject.

I think it was Heron who claimed that direct fuel injection had the drawback of not proving as much cooling of the air fuel mixture as could be obtained from a conventional carburetor. Perhaps moving the fuel injection nozzle out of the cylinder head would help in this respect. It might have also been helpful with respect to facilitating the optimal positioning of the spark plugs. I vaguely recall seeing the claim that the spark plug locations in the DB engines were suboptimal, but don't know if this was referring to the DB 601A or included the later engines (which apparently had repositioned spark plugs). I've seen a DB 601A and do recall that the spark plug placement seemed rather asymmetrical.

Robert

[jjuutinen]

Well, spark plugs were truly optimally located only in the Jumo 213 , Jumo 222 and the sleeve valve designs.