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Hey guys I got a few questions I just installed a compound turbo kit on my 2000 Cummins. My question is why does the small charger need to be set at 25 psi? The lowest I could get it with the Boost elbow is 32 psi when it starts to open, I don't think I can adjust the actuator because it does not have a nut on it. What would the harm be if I just left it at 32 psi? Thanks everybody

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The wastegate is going to control how hard each turbo works.  It also sees total pressure.  So the earlier it opens, the more work the primary will do. ~32 is where mine seems to be happiest.  Good rule of thumb one you get the interstage boost gauge in is to get each turbo to be doing half the work.  

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Total boost would be 30. But yes, 50/50.  And it'll be as close as you can get it. For me, light throttle cruising I'm at 5 from the primary and 10 total.  Moderate acceleration my secondary makes a few more psi than the primary.  and WOT the two are split perfectly 50/50.

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So what do i do if my secondary is 30psi and the primary is say 25? What is the plan of action to get it to a one-to-one? Sorry so many questions I'm just trying to learn and I really appreciate you explaining stuff

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(atmospheric pressure) + (overall boost) divided by (atmospheric pressure) = overall P/R
(atmospheric pressure) + (primary boost) divided by (atmospheric pressure) = primary P/R
(Overall P/R) divided by (Primary P/R) = Secondary P/R
(Secondary P/R x (atmospheric pressure) minus (atmospheric pressure) = Secondary Boost

12+60/12=6

12+30/12=3.5

6/3.5=1.71428

1.71428*12-12=8.57136

 

 

These are Trevors numbers. Secondary pr is low. Be nicer to see it closer to 2.

 

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So i got the bung and gauge done for the interstage boost..can i do the numbers for where the truck will spend its time towing?if so total boost is 30 and primary is at 13-14psi...or does it need to be full throttle run?

So heres the math at utah 14psi ( atmo)

30+14÷14=3.14 (overall)

14+14÷14=2 (primary)

3.14÷2=1.57 ( secondary pr)

1.57×14-14=7.98 (secondary boost)

 

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