1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

Head Gasket Under Boost

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  #11  
Old 01-09-2008, 04:58 PM
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Originally Posted by bullfrog5.9
k so if u blow ur stock gasket then what can u do to make it with stand higher boost psi
Depends how much you want to spend...

12mm head studs will screw in without modification or 14mm if you want to get the head and block drilled and tapped of course..
Marine grade head gasket or other high performance gaskets
O-ringing the head...
Fire ringing..
O-ring the block..more money
 
  #12  
Old 01-09-2008, 06:20 PM
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Cometic has a pretty cool Gasket out, and it can be had with a Oring build in it. No need to machine anything. You do have to make sure the head and the block are flat, no waves or anything. These are MLS gaskets similar to the units on the CR trucks. I would sugest trying one of those along with some 12mm studs and I think that will work fine, as long as you don't have some crazy twins set up or something, but you will have to find more fuel before getting that kind of boost.

Is your gasket blown currently?
 
  #13  
Old 01-09-2008, 08:39 PM
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ok so better gasket will do the trick. when u say 12mm studs what u mean are they longer wider. what wrong with stock ones whats the diff
 
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Old 01-09-2008, 09:59 PM
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from the factory u have bolts, not studs. a bolt only has thread on one end. the stud usually has a thread on either end and a shoulder through the center section of the length. so u thread one end into the block the whole way and the shoulder (wich will stretch less than a threaded section) spans till the nut on the other end where the threads are usually finer. this also saves the block threads cause there is no friction on those threads cause u assemble them first till they stop and then let the tightening be accomplished by the nut where both pieces are easily replaceable should anything happen to the threads
 
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Old 01-11-2008, 09:53 AM
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Advanced timing has a very big part in blown head gaskets, as will anything that accelerates fuel burn (propane or methanol).

I want to talk with whoever has held 60 PSI on a stock headgasket. Maybe a brand new stock headgasket with studs and retarded timing. Definitely don't expect a first gen to hold over 40.
 
  #16  
Old 01-23-2008, 05:35 PM
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I am thinking about swapping out my exhaust housing for a 16cm one...now does anyone have any experience with this and how much more boost will it push?

---AutoMerged DoublePost---

Originally Posted by DieselfreakMI
I am thinking about swapping out my exhaust housing for a 16cm one...now does anyone have any experience with this and how much more boost will it push?
Nevermind ....TST is saying 5-10psi over stock
 

Last edited by DieselfreakMI; 01-23-2008 at 05:35 PM. Reason: Automerged Doublepost
  #17  
Old 01-25-2008, 10:29 AM
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It takes more fuel to make higher boost, not a smaller turbine housing.
 
  #18  
Old 01-25-2008, 12:44 PM
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Originally Posted by Skeye
It takes more fuel to make higher boost, not a smaller turbine housing.
Smaller turbine housing allows for quicker spool, but at higher rpms of the engine the turbo would be spinning faster. The turbo is a compressor so I would imagine if the compressor is spinning faster it would be pumping more air threw the intake, boost pressure is measured in the intake., but there is a point where the turbo loses efficency when it reaches to high of rpms.
 
  #19  
Old 01-26-2008, 10:00 AM
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The common thread here guys is anything over about 45psi is no man's land. Some trucks will take it some won't,there are a lot of variables as said. Persoanlly when i first installed twins, I was thousands of miles away from the nearest machine shop that could o ring. I installed ARP 12's, had the head milled to a 30 RA locally, used a +.010 marine gasket and excersized a very strict torque and re-torque sequence. The truck has held 70+ psi for over two years and 40,000 miles, all with meth, and 22* timing. This is outside the norm, and now that I have moved, I plan on O ringing.

The moral is there is no hard and fast rule, if you up the boost pressure from stock, the risk is always there. What works for me may not work for you and visa versa.

Chris
 
  #20  
Old 04-02-2008, 09:16 PM
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As a general rule, and my personal experience backs this up- the early, non-intercooled engines had a weaker head gasket, and 30psi was about the max for long term reliability. With the 91 intercooled models, everything got the marine grade gasket, and they now say the mid-to-upper 40s is safe. I have had 2 or 3 trucks that would go into the upper 30s, and the gasket held. In my 92, it held 40+ for a while. I replaced the HG because the "nuisance" leak got to be about a gallon of antifreeze every tank of fuel. Still held compression. So, I'd say the mid 30s on an intercooled truck is well within the safe zone. There are exceptions.

DP
 


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