E67 B4001 chart scale kPa values?

[ACCLR8N]

We are adding a turbo to an LE5 powered buggy. Siemens Deka 60lb injectors and 2 bar MAP. The car was previously tuned MAFless and operated for a couple years without issue. I read the tune and I am confused by the pressure scale in B4001. Instead of Vac MAP, it is Delta MAP 128 to 640. I am tempted to just scale it, but I would like to understand the units.

[ACCLR8N]

All my reference files were from 2006 vehicles. The donor for the buggy was a 2009 Solstice. I found a 2007 Sky that had the same table so my confidence has improved that this wasn't the result of previous tuning in another software. I am going to blunder ahead and re-scale the values despite not knowing precisely how this Delta MAP table works...

[joecar]

Rail pressure is 58 psi gauge (i.e. relative to barometric pressure)
this is 400 kPa gauge (wrt baro),
this corresponds to 500 kPa absolute (i.e. not relative to anything),
so the absolute pressure at the top of an injector is 500 kPa.

Now, at WOT, MAP is 100 kPa, this is the absolute pressure at the bottom of that injector,
so at WOT, the pressure difference across that injector is 500 - 400 = 100 kPa.

When throttle is snapped shut (from being open), MAP reaches as low as 20 kPa,
so pressure difference across that injector is 500 - 20 = 480 kPa.


so Delta MAP means pressure difference across any one injector.


( can you see how boost would cause pressure difference to go below 400 kPa...? )



this portion of the new-style B4001 corresponds to 0-80 kPa in the old-style B4001 (LS1B):

Delta MAP kPa Value
400 3.567993
416 3.639038
432 3.706787
448 3.773193
464 3.848999
480 3.890991

[ACCLR8N]

Thank you