Perfect! Thanks! That's what I was looking for.

 

Me and a friend ran our car some exact dyno back to back, his A4 with a GT2871r pushing 32psi and my A4 with a GT35r pushing 32psi. Believe me there was a HUGE difference in power.

I also put that A4 with the GT30r on the dyno back to back with my car and at the very start of the dyno pull my car is making nearly the same tq/hp at 5psi as the GT30r is at 10psi, my car make less power below 4800 rpms but after that its game over. But on that dyno I am running a peak 34psi and the GT30r car is running a peak 27 psi. At 37psi I dont think we are ever going to see a GT30r make 800+hp. lol

You need to start looking at turbo flow charts, you will then see that the amount of flow for 1 turbo is completely different then another turbo even at the same pressure ratio.

 

I used the torque and psi over RPM values from the GT30R 93 octane (and our custom K04 psi over RPM values):



As expected: the K04 was designed and built to achieve mid range torque (2000 to 4000 rpm) with no desire for peak RPM power, and consequently outperforms the GT30R by a good margin in this range. And 'dies' quickly past 4500 RPM. The design was made to 'fit' the modifications (test pipe, clean exhaust, good intake, existing TAP chip, but NO FMIC or upgraded injectors).

Now that we have an ECU to re-chip, and FMIC installed, the next turbo we built will try to get:

RPM Future psi Future Torque Future Power 2000 7 130 50 2500 10 150 71 4000 25 325 248 5500 25 325 340 6000 20 250 286
Likely, using a T3T4 flange (Turboconcepts has a huge selection of housings, compressor and turbine wheels to select and modify to get there), and, if any one, Nick will get as close as physically possible.

Injectors to match, not sure yet how the tuning will be done.

 

I have no doubt that different cars with different turbos, tuning, fuel control, spark control, etc. generate different torque and power at the same psi! But the same engine, fed with compressed air (no matter where it comes from, from a big compressed air tank, a turbo, or else) will ALWAYS generate the same torque at a given RPM with the same intake PSI.

Now, as you stated, the art of turboing (and what makes it so much fun and an ART) is utilize the exhaust energy (itself with myriad of variables) as best as possible to match the desired compressor characteristics (with even more variables).

And that, I leave to turboconcepts ("Turbo Nick"), who, over the past 3 decades, has built more custom turbos for anything on wheels than anyone I have come across (he built for example the Porsche 962 turbos; until a few months ago, he still had his Honda Dax "because I can" turbo mini bike standing around in the shop; currently a bunch of Nissan 300ZX with custom twin turbo V6 and Haltach controls, or the Supra inline 6 blocks are there).

By the way, the "custom K04" we currently have:
K04 – optimized by Turbo Concepts

COMPRESSOR WHEEL
Inducer: 41.0 mm
Exducer: 54.0 mm
Tip height: 5.6 mm
Blades: 6 double,staged, extended tip

TURBINE WHEEL
Inducer: 44.5 mm
Exducer: 40.44 mm
Blades: 12
10 degree clip

Compressor housing shape-matched to larger compressor wheel and blade shape.
Compressor outlet flow optimized.
Turbine inlet flow optimized.
Calibrated waste gate actuator.

Characteristic:

-Turbine modified for faster spool up and increased flow to work/benefit from high flow exhaust system
-Compressor modified to generate early boost, increased midrange power