Quote:
Originally Posted by joedoh
outstanding!
where is that intake pipe running off to?
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Joedoh: the U-shaped pipe that i think you're referring to connects the outlet of the atmospheric turbo to the inlet of the high pressure turbo. I descired this in a bit more detail below.
Quote:
Originally Posted by Rusti
hey man
grate work and fabrication on this truck
one question two turbos ok quite normal on modern diesel engines.
I know a big and a smal one to have boost over the hole rpm range.
So you use either the mal one or the big one
But in your configuration they are one after the other, why? And how do they work? Just doubel the boost?
so long
Arnd
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For this build I decided to go with a compound turbo setup. In most simple terms (and forgive me if I’m going too basic), a compound turbo system combines two different sized turbos (one smaller, one larger), arranged in series to provide a more balanced power curve across the RPM range. Essentially you are combining the quick spooling characteristic of the smaller turbo with the high RPM, big power capabilities of the larger turbo.
Now, to get a little more in to the arrangement of this setup: The smaller turbo is called the high pressure or secondary turbo; the turbine is connected directly to the exhaust manifold and the compressor discharges directly to the intercooler. It is the first to spool up and provides power off idle in the lower RPM range. The larger turbo is called the low pressure, atmospheric or primary turbo; the turbine is connected to the turbine outlet of the smaller turbo and the compressor discharges to the inlet of the smaller turbo’s compressor. By connecting the turbos in series, you are able to reduce the work done by each individual turbo and in doing so increase the output efficiency. Plumbing the turbos in series also allows for a greatly reduced drive to boost pressure ratio (ideal is 1:1).
To visualize how this works in the real world; when you get on the throttle, the small turbo will quickly spool up and provide a quick punch of power right off the line. As the RPM increases and the smaller turbo starts to come out of its efficiency range, the larger turbo begins to light off and take over, continuing to provide power through the higher RPM ranges.
For my setup, I am using an HX30W as a secondary turbo (connected to the exhaust manifold) and an HX35W for the atmospheric turbo (located below the HX30W, kind of hard to see in the pictures). I will post up some better pictures of my turbo setup this week when I take them apart to finish weld everything.
I found this graphic someone else made up (not my work) that illustrates the setup pretty well.
