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Hi. I just bought an early 99 PSD CC w/ 203k miles. I've read a lot of the sites, including spending 2 days reading the threads on this site, and haven't yet seen the response to this question -

What is tha advantage of a turbocharger vs. a supercharger in the 7.3 DI application?

Thanks for your responses - I'm sure I'll learn a lot...
 

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Supercharger has "parasitic" Hp Loss. A turbo is using "free" power to build boost.
 

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CSIPSD said:
Supercharger has "parasitic" Hp Loss. A turbo is using "free" power to build boost.
I wouldn't say it's "free." You have a loss of hp due to exhuast back pressure.
 

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racehauler said:
I wouldn't say it's "free." You have a loss of hp due to exhuast back pressure.

Comparatively speaking it is free...Depending on the turbo set-up and IC set-up it can be a 1 to 1 ratio... 40# back pressure for 35-40#'s boost...
 

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On the other hand there is turbo lag while the pressure builds where a supercharger adds boost with an increase in engine rpm.
 

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The turbo is the most efficient form of forced induction short of the Axial Flow Supercharger (ala Jet engine). You get the most FLOW for a given HP input and the least increase in air temp.

At best, a turbo is about 72% efficient, that is very far from "free" power but much better than the 50% efficiency of a Roots/hEaton style blower.

Blowers will give you the great off-idle Tq like a N/A engine can, but cannot supply the coolish air at the upper RPMs like a turbo (or AFSC).

It's all about the goals. That is why the 6.0L/6.4L have VGTs, it allows a medium-large turbo to flow a lot of air at low enigne RPMs (like a small turbo), but not over-speed at the higher RPMs like a small turbo and still flow the amount of air that is needed to make very good power.
 
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