ya i agree. no way stock motor can do 42 psi, it does not have the fuel, the turbo, or the computer settings for that. not to mention head studs would be needed around that point.
Stock fueling with a boost fooler will net you 42 psi if you stay in it till redline at 3200 rpm's. The stock motor components and HG can easily handle that if EGT's stay in check. HG are good to about 50 psi then you are pushing the limits, 60 psi is a problem waiting to happen.
Is that right? Why when I'm towing with a friend of mine's 05, with all stock components with a set of gauges, does the exhaust temp climb until 1400 and then the boost go from 30 to 42 psi and the egts stay the same. What do you think the electrical actuator does on the turbo? Why would the turbo have a diaphram and an electronic actuator. Huh? High egts is not how Cummins meets emissions. The way they meet emissions is to draw out the combustion process so it doesn't flash. A quick flash creates excess NOx. If you draw out the burn you cut down on the NOx. They do this by retarding the timing and having pilot and post injections.
With stock fueling and no boost fooler you will hit 30-32 psi and hold long before EGT's top at 1400. Same with a BF, you will max boost then EGT's will climb to max a lot slower. If that is not happening the tune is not a stock or there is another issue.
The 5. 9 has no EGT sensor anywhere. Cummins testing felt it was not needed with the boost and fueling the engine has as delivered.
The acutator on the turbo is for the WG and it modulates the WG to keep boost at around 30 psi max. The spring in the stock WG is preset at 26 psi and the WG controller bleeds boost of the compressor side of the turbo to hold the WG closed until 30 psi is reached. The boost is read by the ECU from the MAP sensor and the WG controller reaxts to it thru the ECU.
The ECU uses boost, rpm's, and intake air temp to determine fueling rates across the rpm's. It does not care what the EGT temp is otherwise you could not burn one of these engines down.
Emisions are accomplished with several factors, injection timing, cam timing, and multiple injection events, and in-cylinder EGR. This limits cylinder temps to cut down the creation on NOX which occurs at higher temps.
Diesel fuel does not flash like gasoline, it burns at a fairly steady rate across a wide range of heat and pressure.
You need an FSM for these trucks to understand how they programmed them and how they react. Specs on turbos are only good for ball park figures, you need them in the application to understand how they are functioning.