BOOST

[Reid]

what is the max boost that my stock motor can handle without head studs? I have read the stock turbo can handle 35. I have also heard that a stock 7.3 can handle 30 pounds. But that was the 99-03 and im in a 96.

[d2freak82]

As far as I've read - 40psi, but the MAP sensor can only read up to 25. Which the PCM reads boost from the MAP sensor.
Don't quote me on that, but that's what I've seen and what I follow for pressures - and my turbo hits pretty dang close if not over that. I haven't done studs yet but it's likely coming.

Stock turbo is a different story, but supposedly it'll hit 35 - I would recommend a new turbo if you're going for those numbers though

[Power Hungry]

I've run up to 40 PSI on several trucks without any head gasket issues. The stock MAP sensor will only pull up to 24 PSI. This is due to the fact that they use a 3-bar MAP, but 1 full bar is wasted for vacuum... Which obviously is useless on a diesel.

However, since the MAP is mostly used for low-boost fuel control, by the time you hit 24 PSI you're already at full fuel and the boost level is pretty irrelevant. If you want to know exactly what your boost is, just put a gauge on it and leave it at that.

For reference, you can change the sensor to a full 3-bar, 4-bar, or 5-bar pressure only MAP or 5 volt pressure sensor, and then have the MAP sensor transfer function rescaled for the new sensor so that the OBD will display a correct value. We've done this in the past for special applications where we wanted accurate control of the low-boost fueling (anaeroid) as well as control of fuel up to about 60 PSI. This does require a large number of changes in the calibration and honestly isn't necessary in most applications.

I hope this helps.