how much boost?

[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.

[flguy1215]

OK awesome thanks for the schooling!!! that was very helpful!

[907DAVE]

*quietly goes back into the corner*

[flguy1215]

ok, a couple more questions. first, how does anyone feel about turbo housing mods? my truck is my daily driver family hauler. it sees very little towing and when it does it may be a boat or a small pull behind camper. so would turbo housing be more to my benifit vs. say a gtp38r? for future mods i may put some stage 1 injectors in but thats about it.

and second question, i already ordered a phoenix ( can't wait!!!!) i was wondering if i can upgrade to an FU? Basicly, just pay the difference for the burner? thanks again for the knowledge!!