Boost related questions - stock turbo

[F-127]

Sometimes its just easier to find things, I'm at a slight advantage because I remember reading this a while back.

1) I'm going to pass this question, but here's an excellent post by Cody

Originally Posted by cleatus12r

To elaborate a bit......

The stock turbocharger turbine housing (exhaust side) is very restrictive -- especially on the SD trucks from 99-03. It makes decent boost from a low RPM. This comes at a price though and that price is high RPM flow. If you can't get the exhaust out, then you can't get as much air in. On the other hand, the compressor (intake side) is out of it's efficiency range at anything near 24-26 PSI of boost. Anything beyond that does NOTHING for flow and everything for super heating the air that your engine takes in.

Take this example for instance:
When the stock turbocharger is creating about 25 PSI of boost, the drive pressure (exhaust backpressure between the exhaust manifold and the turbine housing inlet) is just above 50 PSI. Mine ran 52 PSI of drive pressure at 24 PSI of boost before changing turbochargers. I could easily break 30 PSI all day (but I never did it more than twice). The difference in drive pressure and boost causes a severe axial (side to side) load on the turbocharger shaft.....this kills the thrust bushing and causes turbo failure.

Any one of the aftermarket solutions (even including a larger, less restrictive turbine housing) will cause less strain on the thrust bushing and allow a higher volume of flow so the drive pressure remains closer to the boost pressure. This will allow the engine to breathe better and make more power....even on less boost.

If your PCM already has an aftermarket program flashed in it's memory, the Phoenix chip will override it anyway.

2) Boost fooler NOT needed if you're running PHP tunes.

3) N/A, see #2.