5.9L Rotary Performance Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps Related To Performance And Longevity

Pyro

  #11  
Old 05-11-2011 | 10:43 AM
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i cant see where it would be much difference myself your talking the same exhaust within inches of each other
i could be wrong though
 
  #12  
Old 05-11-2011 | 03:08 PM
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i cant see why the front would be any hotter unless u have a injector that is bad or something? i put mine in the down pipe as close as i could to the turbo and 1000 is as hot as it has gotten. i just figure it is a little hotter than that
 
  #13  
Old 05-11-2011 | 07:07 PM
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The temperature difference between the pre and post turbo is anywhere from 200*-500*, depending on how hard you are working the engine(I drive the same road twice a week). I have had both installed on my truck and that was the average difference. So, if the post turbo reading is 1000* then the pre turbo temp could be anywhere between 1200* to 1500*, and with the melting temperature of aluminum about 1250*, there could be some damage done to the pistons.
 
  #14  
Old 05-11-2011 | 11:42 PM
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I put mine in the manifold, no problems so far, i havent heard of anyone breaking them off either, is there really a 200 degree difference between the front 3 cylinders and the back? a while back i remember hearing that #5 cylinder is hottest?
 
  #15  
Old 05-12-2011 | 07:53 AM
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The back cylinders are generally thought to be a little hotter due to less airflow going around the block. The larger temperature difference is between pre and post turbo readings.
 
  #16  
Old 05-12-2011 | 08:45 AM
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The turbo takes heat out of the exhaust stream and uses it to compress intake air; it does this more when it's in its efficiency range, but beyond that it also acts as a flow restriction and you start seeing even more of a difference.

OEM applications know how much fuel and flow they're putting in at what RPM and are looking for a temperature trend to know if something is broken. Hot rod applications are doing their best to burn through the pistons and are constantly pushing turbos out of their efficiency ranges. When tuning an engine you need it before the turbo.

One in each side of the manifold isn't a bad idea by any means.



Now keep in mind that on our engines, the pyro hardly means anything for the duration of a drag or pull as long as you have tons of black smoke coming out of the exhaust. You don't really care how hot it gets; it kinda makes a difference in how fast it pegs.
 
  #17  
Old 05-12-2011 | 11:52 AM
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and if you put it in the manifold do it with the truck running and greese the bit it blows the shavings up and they get caught in the greese saves time from taking the turbo off
 
  #18  
Old 05-12-2011 | 04:26 PM
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Lol bege1 you really shouldn't mess with people that might take you seriously... But you are right, how fast it pegs does turn into more a goal/game than anything else


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  #19  
Old 05-12-2011 | 05:57 PM
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On my 92 my pyro is post turbo and i can make it hit 1000 up a hill empty, i have held it hotter than that pulling and she is still running today. It would be nice to drop the temps alittle. Maybe just turn the pump down would be the easiest and most efficient choice.
 
  #20  
Old 05-12-2011 | 06:23 PM
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Originally Posted by tower_ofpower
Lol bege1 you really shouldn't mess with people that might take you seriously... But you are right, how fast it pegs does turn into more a goal/game than anything else
I'm entirely serious. When you're injecting tons of fuel on a relatively poorly atomizing injection system like what's on a first gen, much of the excessive EGT's are caused by "afterburning" in the exhaust manifold. The fuel has air to burn, but doesn't have time to burn and put all its heat into the piston. The unburned fuel actually absorbs heat from the cylinder similar to water injection, then it finally gets around to burning after it leaves the cylinder. 1600 degree EGT's during racing or pulling on a twelve valve is hardly a sign of imminent failure, unlike common rails which have very efficient injection systems that burn fuel very quickly and do tend to melt pistons at 1400-1500 degrees.

So the relevant information a pyro gives on a modified first gen engine while racing or pulling is how fast it pegs. 1600 doesn't really mean much, what you really want to know is if it's hitting 1800 or 2000, how fast it gets there and how long it stays there after you get off it.

What it really is useful for is while towing or driving really fast up a hill or otherwise putting out sustained power for minutes on end, because that's how long it takes for the heat in the manifold to migrate to the cylinders. But even in that capacity it lies to you; advanced timing, better injectors or different cylinder bowls will cause more heat to be put into the cylinder than what you see on the pyro. 1250 degree EGT's with timing advanced a 1/4" is about as painful on the pistons as 1350 degree EGT's with timing at the stock levels.
 

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