Problems with scaling P2s
05-27-2011, 07:12 AM
#77
Registered
I'm currently remote tuning an NA engine in preparation for FI . The owner has fitted yellow uncapped injectors in the P2 position . These should flow around 750ccs according to the data from the shop that flow tested them.
However if you look at what happened when I scaled the injectors to accomodate 750cc you can see that it went very lean .
To get back to where the stock injectors were I had to scale them by only 12% .
Only reason I can think of for the low flow is that one of the injectors is not working at all . If this were the case how would we go about testing this ?
Can anyone else see any other possibilities ?
Ignore the 8000rpm result - that is another issue to be resolved .
However if you look at what happened when I scaled the injectors to accomodate 750cc you can see that it went very lean .
To get back to where the stock injectors were I had to scale them by only 12% .
Only reason I can think of for the low flow is that one of the injectors is not working at all . If this were the case how would we go about testing this ?
Can anyone else see any other possibilities ?
Ignore the 8000rpm result - that is another issue to be resolved .
Those bigger injectors on the "P-2" position really richen the mixture when the APVs open.
Since you are remote, I think you need to specify that "P-2" is the two center positions of the 4 injector fuel rail.
05-27-2011, 03:21 PM
#78
Good point .
05-30-2011, 12:13 PM
#81
In fact, the opening of the APV is often the source of a considerable lean-spot.
The P2s are not tied to RPM like the APV, but load.
Furthermore, since they are in the primary intake tract, their contribution to the fuel delivery is pretty consistent.
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