Peak when? Cold acceleration? Max boost at max rpm? Max power conditions?
All those operating points at sea-level winter or max expected altitude in summer?
I know drive pressure climbs . but you can limit how far it goes .
You can only limit how far drive pressure goes (absolute) by limiting boost (absolute) through wastegating. That's it. Otherwise you need to physically change turbo geometry which has it's own problems.
Further, as RPM and turbine flow increases, drive to boost ratios get worse. If you want to limit drive pressure then you have to wastegate more and more with climbing RPM. Which drops boost more and more and while your absolute numbers might be lower, the ratios don't change much.
You get the best drive/boost ratio at full rpm by keeping the wastegate shut and limiting fuelling to keep the compressor on the map. But power production sucks.
I get the impression no mater what I say your mind is made up on the matter . Which is where I'd normal share the raw data . But I won't on this topic as it's not my data to share and could Land me in hot water.
I hope u do revisit the drive pressure logging and add shaft speed to you info .
Well yes because the laws of thermodynamics are pretty rigid things. If you can find and prove any exception to them then you'll be receiving the next Nobel prize.
I really have no idea what you're getting at here. It's like you're hinting at some great untapped secret through setup that can magically alter the boost to drive pressure relationship (which is incredibly complex) or the shaft speed to PR and flow relationship (which is a lot more straight-forward).
I can assure you there is no magic. Anyone who claims there is is either mistaken or bullshitting.
Drive pressure is required to create the pressure difference and expansion for turbines to operate. Different turbines have different performance which results in different turbine maps. These maps relate intake conditions to delta P and power produced. Wastegating cannot and does not alter those maps. It simply moves the operating point on the map. More wastegating = less flow through turbine and less power from the turbine.
This is exactly the same discussion I've had with many proponents of "wastegate porting". Which; BTW; is a complete waste of time unless your problem is too much boost with the flap wide open.
Shaft speed creates the compressor tip speed which creates the radial flow that creates the pressure ratios. If you drop shaft speed without changing intake conditions then you're also dropping P.R.
There is no magic. Turbo sizing is all about picking the compromises you can live with.
Did you notice that the worst ratio in my above example was 37/30 = 1.23?
Best ratio 26/30 = 0.87
Would you like to comment on that?