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Discussion Starter #1 (Edited)
Do you have to get your head O-Ringed for compounds or just head studs and 60# valve springs? I was going to do the H1c (will probably upgrade later), over an HT3B.
 

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Discussion Starter #2
Anybody???
 

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Id would just to insure reliability, are you doin a head gasket?
 

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Discussion Starter #5
Yeah, I'll probably go ahead and do that aswell while I have the head off. Do I need to fire ring it, because I really don't want to take the whole block apart.
 

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Discussion Starter #6
What's the max boost without having to get head studs?
 

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I have a '98 12v, and I'm currently getting away with 50 psi on stock bolts and gasket. I also have my timing set at 18.5 degrees, though it may effectively be less because I just put new injectors in it with a higher popoff pressure. It doesn't have the sharp diesel rattle like 19 degrees would with lower popoff pressure.

I wouldn't guarantee you can get away with this much on a stock gasket and bolts, and I'm probably on borrowed time, but I'd think at least 50 would be safe with properly torqued studs and a stock gasket.
 

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Discussion Starter #8
Thanks, this is very helpful. I'll probably just go ahead and build the twins when I can get the HT3B and get studs later, just keep an eye on my boost gauge :thumbsup:.
 

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Discussion Starter #9
Are there any seals in the turbos compressor housing that can be broken, I'm wanting to take the compressor housing off and polish it on both turbos when I get my HT3B :).
 

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Discussion Starter #10
Where can I get this piece?
 

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PDR built that piece. I'm sure they would have another. Piers Diesel Research or so it used to be known as, google. It's probly high dollar. I'd space the big charger out away from the block and not build it like the run of the mill 2nd gen and 3rd style twin sets. Will help in various ways.
 

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Do you have to get your head O-Ringed for compounds or just head studs and 60# valve springs? I was going to do the H1c (will probably upgrade later), over an HT3B.
You don't necessarily have to run studs to run twins, and you definitely don't have to have stiffer springs. Some can run fiddy PSI on stock bolts, retorqued properly. Studs would be on the safe side, though.

You only need heavier valve springs if you're turning high RPM (4K+).
 

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Where can I get this piece?
It's my understanding that is stock/OEM on a Cummins N series engine.

They call it a Cobra-Head down-pipe. :confused013:

PDR simply machines for and welds a V-band flange on it. :)




The other half of the V-band flange is welded to a plate (flange) for the HT3B.




 

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The cobra pipe is also used on 8.3 C series Cummins in some school buses. I snag them up if when I encounter them at my engine junkyard. A few years ago they were about $90 from Cummins. The other option you could do instead of welding a v-band flange is cut threads in it on a lathe. Then the same to your large turbo flange.
 

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Discussion Starter #15
Thanks guys, I looked at the flanges already, they're $45. I'm going to get studs soon, just not right now. Can I hook up an external wastegate and set it at 50psi so it don't get over that?
 

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Discussion Starter #16
What do I do about the heater lines when I flip the manifold over? I'm taling anbout the little bracket that holds them up, do I just let them hang or build another bracket?
 

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Discussion Starter #17
Does anybody know how to fab up an external wastegate to keep boost under 50psi?
 

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IMO i would do the headstuds before the twins. your head gasket and bolts are only rated for 35psi of boost. but just a thought its your truck your choice
 

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Discussion Starter #19
I'm going to get headstuds eventually, I was just going to put the external wastegate on right now to keep boost ok till I can get them. I've heard from several people say they can get 50psi without studs and a thicker headgasket.
 

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with all of the fuel your going to need to spool twins i personaly would feel like waste gating at a low pressure would be a waste. if thats the case i would just run a single. i personaly dont get the point of doing a thicker head gasket and not studs ether but it is your truck to each there own. i just personaly like a strong foundation and not always have the worry of somthing i cheaped out on failing
 
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