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

Poor MPG with HX35

Old Jan 2, 2013 | 01:29 PM
  #1  
TTipsword's Avatar
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Default Poor MPG with HX35

Anyone else swap to an hx35 and see a big loss in MPG? was getting 24 minimum on higway and now with the hx35 im seing 15.6 or so?
 
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Old Jan 2, 2013 | 01:47 PM
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I swapped to a he351cw and went from 21 to 15. I think it is the smaller exhaust housing, but Idk for sure..

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Old Jan 4, 2013 | 05:58 PM
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i have been told by several people that putting a bigger turbo on will ruin you MPG. they couldnt tell me why though
 
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Old Jan 5, 2013 | 01:31 AM
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im also interested in finding out about this...

i have a cobra head turbo back from a 8.3 and and 5in stacks i was going to install and was going to switch to the hx35. if the mpg drops that bad id just upgrade the h1c.
 
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Old Jan 24, 2013 | 02:45 PM
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I would be very interested in why? I was planning this on my 1st gen. I have a HX35W. Was any other mods done to fueling, to lose MPG?
 
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Old Jan 24, 2013 | 04:36 PM
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I didnt see a difference when I did mine. was always around 17mpg wth he h1c and im still at 17mpg. but I do have a thread open to increase my mpg
 
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Old Jan 24, 2013 | 07:25 PM
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Is your cruise boost higher than it used to be? You can use boost to predict MPG just like you can via vacuum (or lack there of) in a gas engine. The more boost you are creating, the lower your MPG will be. Yes a smaller exhaust housing is most likely the dirrect cause.
 
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Old Jan 25, 2013 | 08:26 AM
  #8  
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ya had to be the housing. just not a good setup i suppose. i liked the boos in power over the powerband with the fast spool up but the egt's got crazy quick. And no i did no other fuel upgrades with the swap.
 
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Old Jan 25, 2013 | 08:44 AM
  #9  
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I had the same issue with my truck when I had an HX35
 
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Old Feb 22, 2013 | 10:35 AM
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I have the h1c I believe and the 21cm housing. Looking at putting an hx35 on and as long as it doesn't have a small exhaust housing it would be a good upgrade?
 
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