Compounds, Wastegates... equal pressures...

A

angelic0-

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May 9, 2009
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Ok, so... after someone asked me... "Your HX40 is making 40psi of boost?"

I put a little thought into it, got to reading... and from what i'm reading... if my boost gauge reads 80psi, the HX40 should be making 40psi and the HX60 40psi aswell... combined... 80psi...

With the wastegate on my HX40 set to 22psi, this should be impossible ??? unless the wastegate on the HX40 is sticky.... and with regulated shop air 22psi opens up the wastegate...

So, is the HX60 really pushing 60psi, and then... HX40 pushing 20psi ??

I really thought i had this.... but now i'm confused :bang

I've even has a boost spike with 100psi, timing @ 20° resulting in a blown HG...

I'm going to fire ring it, set timing to 18° and try to keep it "civilized" @ 75-85psi...

I pull my 30' toyhauler every now and then, and EGTs have been in check, i can bury the pyro @ 1800° in a 1/4 mile run... but towing @ normal speeds i never see temperatures over 1300° and only on hills... probe is pre-turbo...

Since Cummins says 1250° pre-turbo is normal for prolonged periods, i don't think i'm too crazy...

Exhaust housing sizes are 16cm2 and 32cm2...

Stock injectors would make 35psi on this setup pretty easy, a little late spool... with my current injectors it spools quick and as said... have seen 100psi !
 
hmmmm, you have much reading to still do.


the turbo sense is not strong in this one.
 
The main two things to be aware of are.....

1)The secondary multiplies the boost of the primary.

2)Psi is just a number used to measure the pressure ratio. All calculations must be done using P/Rs, not psi.

Do some searching, and you'll find a lot of post on how it works and how to calculate.
 
I beleive the boost from the secondary is what gets the primary spooling...

I have mine set to open the wastegate on the secondary @ 22psi, to lower drive pressures, but i guess that with a 16cm2 exhaust housing i might raise the wastegate to such numbers as 40psi...

I beleive that the air compressed by the primary enters the secondary and gets compressed further there, i am not monitoring the primary boost...

I only have a boost gauge reading from the inlet on the AFC, and i have seen a 100psi maximum, maybe even more since my boost gauge only reads 100psi...

At that point, the head gasket gave in and it limped on it's face...

Have been experiencing timing slip, but i have gotten past that problem now...

I am going to be stripping the motor out of the truck in the next coming days, and will fire-ring it, thinking wether i should put a MLS gasket on it or a stock gasket, and get new ARP studs for it...

I am also going to install a backpressure gauge on it...
 
with fire rings you will have to run the gasket for the fire rings because they take the place of the compression ring in the gasket.
 
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