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PSD vs IDI fuel economy

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Rusgo, Nov 5, 2019.

  1. nelstomlinson

    nelstomlinson Full Access Member

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    My IDI is rated at 185hp, my powersmoke at 225hp. I drive like an old man in either, so I'm not usually using the extra fuel the powersmoke turbo allows over the NA IDI.

    All the fancy computer stuff is all about emissions, as someone else said.
     
  2. Rusgo

    Rusgo Full Access Member

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    Yeah I agree, peak HP doesnt mean much in relation to economy if you never ask the engine for it.

    Before I installed the turbo, I couldn't get worse than 16mpg if I tried. Best ever was 19mpg. It was so slow, and my Ip was so old, it made me drive like a grandma. Post turbo and fuel system refresh, grandpa mpg is still the same, but if I get into it all the time, mileage drops fast.

    Though most people use the power if they have it. Goes along way to explain why people dont get better economy with modern engines in general.

    Sent from my SM-G975U using Tapatalk
     
    Last edited: Nov 6, 2019
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  3. Kevin 007

    Kevin 007 Full-floater

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    Yeah new trucks use the same amount of fuel with 3x the power for the same fuel burnt.
    The overall cost of ownership long-term however....is significantly higher with newer trucks tho with massive repair bills every time the check engine light comes on. And we'll see if they are even still running in 30+ years like our idi's. I doubt it
     
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  4. renjaminfrankln

    renjaminfrankln Supporting Member Supporting Member

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    16 average 19 highway with the truck in my signature

    265/75/16 tires and 3.55 gears
     
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  5. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    Your sig is not showing up?
     
  6. renjaminfrankln

    renjaminfrankln Supporting Member Supporting Member

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    You may be on mobile? Its an 89 4x4 with banks turbo and ZF5
     
  7. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    Duh.....mobile.
     
  8. ttman4

    ttman4 Last Nite's Dream..

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    Well whatever guys. Not been contesting any PS's lately, & I know this thread is us vs them. LOL

    All I know is that when Bessie was newer she used to get 18-22 all the time.
    She's in my sig.....'90 DRW, CC, 7.3 IDIT turboed, ZF5, 4.10

    I had her turboed with a ATS 088 kit when she had about 300 miles on her, & they turned up the pump.....then of course I had to turn it up some more when I got home. LOL Put lots & lots& lots of miles on her & she used to get 18-22, sometimes 23. Pulled lots of really big, stupid a** big loads with her & she'd get 13-14 loaded.
    She'd get 80-100K miles on pump & injectors & milage be down to about 12-13-14 empty. Pull Pump & inj & have them rebuilt & milage be back up 18-22 empty again.

    Now with this '94 factory IDIT I got in her now she does good to get 13. Blow smoke & Runs & pulls awesome. Does it like a scalded dog chashed by a stripped ape.....at 13mpg!!! However fuel ain't what it was 20-30-40 yr ago either.

    Got to get with Russ & get some injectors!!! Just been so busy & sidetracked it's plain unreal.... that's another story tho.
     
  9. Chief

    Chief Registered User

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    I think you’re on to something here. The ULS diesel has less lubricating properties that can be harmful to our fuel systems. But does it affect fuel mileage to? We can put additives in that will bring up the lubricating properties but does it really perform as well as the LS diesel our trucks were meant to run on?
     
  10. MtnHaul

    MtnHaul Supporting Member Supporting Member

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    In regards to fuel quality I recall reading, somewhere?, that the process of removing sulfur also removes the lubricity and lowers the cetane rating. I also recall that US diesel tends to have a lower cetane rating than diesel in some foreign markets. IF higher cetane ratings contribute to higher MPGs then I'm all but sure the oil refineries here would prefer a lower rating in the interest of selling a bit more product. Call me cynical if you like.
     
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  11. Cubey

    Cubey Full Access Member

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    Some diesel additives claim to increase cetane rating, in addition to adding lubricity. How much it helps, I don't know.

    This is what I have been using for most of the past 2000 miles in the motorhome because it sat so much and I wanted to clean up the IP and injectors: https://www.howeslube.com/products/meaner-power-kleaner

    It doesn't claim to add cetane, but it claims to clean injectors and adds lubricity.

    I may switch back to buying Power Service Diesel Kleen though, since it does both of those plus claims cetane boost. PS costs more per dose but eh. I used PS in the truck except last winter some when I was using Howes for antigel.

    Since we pretty much NEED to use an additive to help with lubrication, we may as well use something that claims to boost cetane too when we don't need antigel.

    I don't think antigel is worth bothering with for me most of the time. I think only once did I see my fuel gel any and that was a couple years ago when it got down to around 7 degrees one morning. I had antigel in it and I never had a problem starting the truck. It has a clear plastic fuel filter just before the tiny electric fuel pump and it looked cloudy when it got down that cold.

    Usually I don't see temps that low though. I have been sticking around the Texas area of the country in winter.
     
  12. 79jasper

    79jasper Chickenhawk

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    Sure, it's not fully scientific, but enough for me to avoid some.

    Sent from my SM-N960U using Tapatalk
     
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  13. Cubey

    Cubey Full Access Member

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    Well, the PS 911 is just meant to unfreeze in an emergency, not do much more. Too bad the PS grey bottle wasn't tested too. The Hot Shots stuff is pretty expensive, but in his "tests" it was one of the best.

    Howes anigel did the worst for lubricity? I guess that's why it's the cheapest. I guess I will stick to Power Service stuff.
     
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  14. Rusgo

    Rusgo Full Access Member

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    If you count all the comments as peer review...definitely science. I'm convinced. Just used hotshots for the first time last month. Saw it on amazon randomly. Wasn't expecting anything so wasn't even paying attention. Over the next few days I kept thinking how much smoother the engine runs and pulls. Less clacking too. Then realized it was the hotshots.

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  15. nelstomlinson

    nelstomlinson Full Access Member

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    Someone told me that removing the sulfur also reduced the density of the fuel, and lowers mileage.
     

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