raueda1
6/27/2017 11:02 AM
The CIS manual in the members section (1976-1979) only distinguishes between 6 and 8 cylinder engines and sometimes by year. No distinction is made for actual size or model. Interestingly the pressure specs and settings seem to be the same all around. For example, is the fuel pressure or volume delivery spec the same for the 4.5L and 6.9L engines? Presumably "yes," because no distinction is made. Yet that seems impossible on the face of it, I can't believe that the full-throttle fuel flow, for example, is the same in a 4.5L and 6.9L engine.
Taking it a step further, there is a lot of non-Mercedes info on the K-Jetronic system out there - WUR settings, etc etc. Is the k-Jetronic design "universal" across different cars? for example, are the WUR pressure specs the same on a m100 6.9 and Porsche 928 V8?
I'm puzzling over what info is engine specific and what (if anything) is common to the system regardless of model. Never assume and all that. Insights welcome! Thanks,
Dave
S class
6/28/2017 6:20 AM
THink of it this way, the 6.9 engine will draw more air into itself than the 4.5 engine for the same throttle opening. More air drawn through will deflect the air meter flap more, meaning the fuel distributor metering piston will move further, and the injectors will spray harder in the 6.9 engine than in the 4.5 engine, even though the supply pressures are the same, and the injectors themselves are the same.
116.036 - trusty rusty
116.036 - Rooikat
116.024 - the merc
116.028 - Penelope
116.032 - Esmeralda
126.037 - Scheckter
126.037
107.046
RANDYS
6/28/2017 7:13 AM
It is true the 350/450/6.9 use the same "back end" fuel delivery system, fuel distributor, and injectors.
The WUR's are another matter, generally interchangeable but some times are the same depending on era and end destination.
The air mixture box is debatable. I suspect the 450 is slightly smaller diam.......this is something I am working on so it's not yet confirmed.
However, whilst the K Jetronic is largely "generic" in principle of operation, whether it be fitted to Merc//Toyota..Porsche etc, the air mixture box, WUR, aux air valve vary in size and functioning . Only the injectors are common from inception to about 1981.
The other variable is of course the diam of the throttle body.
Ron B
8/31/2017 10:41 PM
A 560 has a lot bigger throttle body than a 6.9 but in general the Kjet is only operating at 10% of it's capability. I have seen a volvo engine producing 750 HP with a standard WUR, Airflow meter and injectors.