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Thread: Diesel MPG Tuning

  1. #1

    Default Diesel MPG Tuning

    Anyone here ever done performance tuning for better diesel MPG?

    What I have in mind is to tune the fuel lower, adjust the timing, and lower the boost, and see if there is a stable, safe, lower torque, lower HP, lower fuel, lower performance level that I can tune it to.

    Then, my plan would be to hook up an Edge Juice or similar unit to tune it back to the stock level and to higher performance levels on-the-fly.

    Has anyone ever tried such a setup?

    Thanks, Gene
    Last edited by Climer97007; October 23rd, 2008 at 08:14 AM. Reason: mispelled
    1949 Dodge Power Wagon Crewcab Project
    2002 Cummins ISBe170 3.9L 4 Cyl. Common Rail Turbo Diesel...
    NV4500 5 Speed, NP205 Transfer Case...
    14 Bolt and Dana 44 Axles...
    Dream motor might be a 6.6L Duramax V8 (LB7)
    503-627-5774 (Work)
    503-267-1648 (Mobile)

  2. #2
    Senior Member DmaxHawk's Avatar
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    I would stay away from putting it in the Edge just my .02. I think that the edge would screw up the programming considering it 'tricks' the ECM. You've got the right idea for the tune except for the fuel. You don't want to take fuel away, instead add it. The reasoning for this is that if you take fuel away, it takes more time with your foot on the pedal to get going to speed which in turn takes mileage away. I first thought the same as you when I started building mileage tunes so I tried making it run lean. The outcome was my tune got 17mpg hand calculated with GPS miles and fuel pump gallons. And a PPE tune rated at 350HP got 21 MPG.

    If you read around other forums (dieselplace.com is a great resource), they will tell you that they see the greatest mileage in the highest level tunes.

    So for your tune...You need to lower boost to nearly 0 psi like you said but only in the cruise area otherwise it will greatly affect driveability. Advance timing, again in the cruise area. And increase fuel.

    This will result in a high-mileage tune still with enough get-up to pass someone in a hurry if needed.
    PM me if you would like to see my tune I made for my LBZ
    07 El Bee Zee
    Little faster than stock...

  3. #3

    Default 1500 Lb Hot Rod with a Duramax

    Quote Originally Posted by DmaxHawk View Post
    You've got the right idea for the tune except for the fuel. You don't want to take fuel away, instead add it. The reasoning for this is that if you take fuel away, it takes more time with your foot on the pedal to get going to speed which in turn takes mileage away...So for your tune...You need to lower boost to nearly 0 psi like you said but only in the cruise area otherwise it will greatly affect driveability. Advance timing, again in the cruise area. And increase fuel... This will result in a high-mileage tune still with enough get-up to pass someone in a hurry if needed. PM me if you would like to see my tune I made for my LBZ
    This Duramax motor is going into a 1500 Lb Hot Rod. I don't see the need for the extra oomph to pass someone. It is not like I'll be pulling a horse trailer up the pass.

    I do not see how it can possibly be true that for a given RPM, if I increase the fuel, that I can use less fuel at that RPM. It is non-sensicle to me.

    My plan is to lower the vehicle weight, only 1500 lbs or so, and decrease my drag and wind resistance as much as possible, tall narrow tires, etc..., and then to work at lowering my fuel useage across the board to save on MPG.

    If it accelerates like a snail, that is OKAY, because this profile is about MPG performance, not 0-60 performance. I don't need HP and Torque until I am ready to Rock-and-Roll with the Hot Rod. Then I can select a Hotter profile and turn the fuel screws on...

    Fact is, on the DieselMarine website, and even on the Cummins Marine website, you can see the published fuel curves of each motor vs RPM vs HP and Torque. The same displacement motor burns more fuel at RPM to get more HP. The motor may be more efficient in terms of how much less waste it has at that RPM and performance level, but, if I don't need that performance level at tha RPM, then it seems to me that I am still wasting fuel at that RPM.

    I'd love to see a fuel curve for the motor that is getting mapped more fuel, but is actually using less fuel per RPM. Somehow, I don't think this fuel curve exists. I'd love some links to a fuel curve showing that the -miracle happens here- is actually possible and happening.

    Thanks,

    Gene
    1949 Dodge Power Wagon Crewcab Project
    2002 Cummins ISBe170 3.9L 4 Cyl. Common Rail Turbo Diesel...
    NV4500 5 Speed, NP205 Transfer Case...
    14 Bolt and Dana 44 Axles...
    Dream motor might be a 6.6L Duramax V8 (LB7)
    503-627-5774 (Work)
    503-267-1648 (Mobile)

  4. #4
    Junior Member
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    You should download the software and look at a stock duramax tune. When he says add fuel it doesn't mean at a specific RPM. Its kinda hard to explain. There are many tables that get reference to come up with how much fuel goes in. Stock my truck took about 35-40% TPS to go 55-60 on a flat road. After adding some timing and fuel it took about 20-25% to do the same. It was using less fuel at 20-25% than it was at the old 35-40% so that means better MPG. Now if I push the pedal up to 35% on the new tune I go faster than 55-60. 75% TPS is way more power than stock but 20-25% is all I need now to go 55-60 instead of 35-40. Not really sure if this makes any sense but this how you can get power and MPG all in one tune. Fuel is not just a curve based off RPM. Lots of factors go in. The skinny pedal dictates MPG. I get better millage on a tune that adds 150hp when I stay out of the throttle than I do on the stock tune. Build the tune so it gets millage in the cursing range and makes power when the TPS is high. Again sorry if none of this makes sense its getting late.
    '04 LB7, AEM Brute Force HD Intake, 4" into 5" single stack, Kennedy Boost valve, EFILive

  5. #5

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    I downloaded the program already. So far, I have looked at the various Maps. I have to admit that there are so many Maps, I am not sure where to start. There is going to be a steep learning curve here I think. I can understand how the TPS position can be reprogrammed to reflect different RPM levels, for example, but, how that relates to adding fuel and getting better MPG at a certain RPM is still beyond me. I am still sceptical, not having seen this tuner in action. I think I just need to see it in action to really understand it. Like I said, I am a visual person.

    Is there anyone on this list living in Beaverton or Portland, Oregon? I'd love to see an A vs. B tune in action, to see the added fuel, and to see the lower fuel consumption at a specific RPM.

    Thanks, Gene
    1949 Dodge Power Wagon Crewcab Project
    2002 Cummins ISBe170 3.9L 4 Cyl. Common Rail Turbo Diesel...
    NV4500 5 Speed, NP205 Transfer Case...
    14 Bolt and Dana 44 Axles...
    Dream motor might be a 6.6L Duramax V8 (LB7)
    503-627-5774 (Work)
    503-267-1648 (Mobile)

  6. #6
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    Little update man, there's a really good chance Ill be headed down to Portland either friday the 7th or 14th of November for the weekend. We could probably meet up for an hour or so on the corresponding Sat and I could walk you through the software a bit. I only know a little bit about the diesels but I can show you some tricks in the software and show you a higher hp tune vs a stock one.

    Guess I talked about meeting up in a different thread, my bad.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  7. #7

    Default Let's Get Together Then

    Quote Originally Posted by ScarabEpic22 View Post
    ...Ill be headed down to Portland either friday the 7th or 14th of November for the weekend. We could probably meet up for an hour or so on the corresponding Sat and I could walk you through the software a bit.
    Hey, I'd love to meet up with you. I am usually working on my Power Wagon Project on Saturdays. Maybe you can meet me there? I bet the the guys would love to see what you have here. Most of them are old school hot rodders, but, I am trying to bring them into the 21st century little by little... Give me a call when you know the weekend.

    If it slips out to Nov. 23rd, I'll be down in Grants Pass. I hope to meet up with you before then. Looking forward to it. Gene
    1949 Dodge Power Wagon Crewcab Project
    2002 Cummins ISBe170 3.9L 4 Cyl. Common Rail Turbo Diesel...
    NV4500 5 Speed, NP205 Transfer Case...
    14 Bolt and Dana 44 Axles...
    Dream motor might be a 6.6L Duramax V8 (LB7)
    503-627-5774 (Work)
    503-267-1648 (Mobile)

  8. #8
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    Quote Originally Posted by Climer97007 View Post
    Hey, I'd love to meet up with you. I am usually working on my Power Wagon Project on Saturdays. Maybe you can meet me there? I bet the the guys would love to see what you have here. Most of them are old school hot rodders, but, I am trying to bring them into the 21st century little by little... Give me a call when you know the weekend.

    If it slips out to Nov. 23rd, I'll be down in Grants Pass. I hope to meet up with you before then. Looking forward to it. Gene
    Great, and it will either be one of those weekends or none at all until January as I have to head home to Seattle for Thanksgiving and then finals are shortly after that. Ill let you know what happens!
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  9. #9
    Lifetime Member vortecfcar's Avatar
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    Quote Originally Posted by Climer97007 View Post
    This Duramax motor is going into a 1500 Lb Hot Rod.

    I'd love to see a fuel curve for the motor that is getting mapped more fuel, but is actually using less fuel per RPM. Somehow, I don't think this fuel curve exists. I'd love some links to a fuel curve showing that the -miracle happens here- is actually possible and happening.

    Thanks,

    Gene

    Gene,

    What it boils down to on these engines is that if you don't need the fuel at that RPM, then you don't need that RPM. Max efficiency is at max torque, which is at lower and lower RPM (until you snuff the turbo).

    What you would want to do is tune the transmission to shift low and use the lower section of the rev range. It's not about fuel per RPM, its about fuel consumption per HP.

    When we say add fuel, we mean add torque at said RPM, which means add HP at a given RPM, which increases engine efficiency (HP/fuel consumption).

    If you pull fuel (torque), you have to use RPM to make horsepower. Revs cost fuel. You'll see lower HP/fuel consumption numbers at 3000RPM than at 2000 RPM.

    Hope this clears things up a bit,

    Nick

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