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Thread: Fuel mileage tune??

  1. #1
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    Fuel mileage tune??

    Been messing around with building tunes for my truck for awhile now, but those are more geared towards power.. Wanting to build a tune with the great mileage in my mind.. I know lowering rail pressure in the cruising area and messing with timing in those areas as well will help.. But is there anything else?.. Maybe pilot injection/timing?

  2. #2
    yes, drop rail pressure down to 10~12k in the cruise zone all the way up to 2400ish rpms and rest the timing. then reduce pilot qty down to 3-3.5 in that same region and rest main timing. if you have ratgle that does not go away then minor advances on the pilot timing.

    your goal is to find the timing point where you have a slight haze while cruising then you have 2 choices you can use, cut duration 2-4% across the table or dial timing back a tad bit more.

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    Quote Originally Posted by steve05ram360 View Post
    yes, drop rail pressure down to 10~12k in the cruise zone all the way up to 2400ish rpms and rest the timing. then reduce pilot qty down to 3-3.5 in that same region and rest main timing. if you have ratgle that does not go away then minor advances on the pilot timing.

    your goal is to find the timing point where you have a slight haze while cruising then you have 2 choices you can use, cut duration 2-4% across the table or dial timing back a tad bit more.
    Ok, thank you! Ill look into that tomorrow

  4. #4
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    Wanting to do something similar soon, but I'd like to kill the pilot and post above 1600rpms,
    BUT I also have to cruise about 2250rpms/80+mph, so seeing a haze at that speed will be impossible. Any thoughts or ideas?

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    Senior Tuner Jim P's Avatar
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    Lol have to cruise at 80+ mph?

  6. #6
    yes, speed limits in some areas are 80... and your cruising at 85...

    @JDSDiesel, you could set your fueling then at 2250 rpms look for smoke. Adjust timing until you see smoke, then trim it back until its gone... then set the timing based on those 2 numbers.

    Or... hold 2250 rpms in a lower gear at a lower speed.

  7. #7
    Senior Tuner Jim P's Avatar
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    I don?t really think anyone is twisting anyone?s arm to have to do 80+mph... more of a free choice... I won?t drive 80+mph just because that?s what the posted limit says, the seconds saved isn?t worth the cost of fuel required to move these trucks at those speeds. Drag coefficient quickly drops mpg at those speeds

  8. #8
    Tuner in Training bluessmax's Avatar
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    Quote Originally Posted by steve05ram360 View Post
    yes, speed limits in some areas are 80... and your cruising at 85...

    @JDSDiesel, you could set your fueling then at 2250 rpms look for smoke. Adjust timing until you see smoke, then trim it back until its gone... then set the timing based on those 2 numbers.

    Or... hold 2250 rpms in a lower gear at a lower speed.
    You sure on this? I have done a ton of testing in these areas and have not found it to realistically help economy.

    One thing to remember is the vehicle will always take "x" power to drive "X" speed. So if the truck requires "X" MG of fuel with "X" amount of air to meet a horsepower target to maintain speed... Then it will always have to have that rate pretty well regardless.

    - Cutting rail pressure is lowering the injection timing in itself essentially... which will yield a lower density to the chamber due to having to have a larger spray pattern (Injection duration) to still meet the required fuel to air to meet that horsepower level it takes to drive the speed requested.
    - Lowering pilot/pilot timing really does not help much at all in my testing. The pilot and pilot timing actually helps the atomization a good bit pre warmining the chamber and making the main shot that much more efficient.

    - Cutting post injection (if equipped) indeed will help fuel economy

    - Adding main timing will indeed help fuel economy

    - Having the proper amount of fuel put in with the airflow ready to go early helps economy as it allows less rpms - which if you check out the VE table of these gals boosted - you can see they are very efficient down low.

    Just my 2 cents :-)
    Diesels and stuff

  9. #9
    Senior Tuner Jim P's Avatar
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    Quote Originally Posted by bluessmax View Post
    You sure on this? I have done a ton of testing in these areas and have not found it to realistically help economy.

    One thing to remember is the vehicle will always take "x" power to drive "X" speed. So if the truck requires "X" MG of fuel with "X" amount of air to meet a horsepower target to maintain speed... Then it will always have to have that rate pretty well regardless.

    - Cutting rail pressure is lowering the injection timing in itself essentially... which will yield a lower density to the chamber due to having to have a larger spray pattern (Injection duration) to still meet the required fuel to air to meet that horsepower level it takes to drive the speed requested.
    - Lowering pilot/pilot timing really does not help much at all in my testing. The pilot and pilot timing actually helps the atomization a good bit pre warmining the chamber and making the main shot that much more efficient.

    - Cutting post injection (if equipped) indeed will help fuel economy

    - Adding main timing will indeed help fuel economy

    - Having the proper amount of fuel put in with the airflow ready to go early helps economy as it allows less rpms - which if you check out the VE table of these gals boosted - you can see they are very efficient down low.

    Just my 2 cents :-)
    Agreed, other than I?ve found pilot timing to make a very noticeable difference in fuel economy when adjusted and zero difference in fuel economy with post on or off. These engines are very efficient down low but high engine efficiency doesn?t equal high fuel economy. Big difference between engine efficiency and fuel economy.

  10. #10
    Quote Originally Posted by bluessmax View Post
    You sure on this? I have done a ton of testing in these areas and have not found it to realistically help economy.

    One thing to remember is the vehicle will always take "x" power to drive "X" speed. So if the truck requires "X" MG of fuel with "X" amount of air to meet a horsepower target to maintain speed... Then it will always have to have that rate pretty well regardless.

    - Cutting rail pressure is lowering the injection timing in itself essentially... which will yield a lower density to the chamber due to having to have a larger spray pattern (Injection duration) to still meet the required fuel to air to meet that horsepower level it takes to drive the speed requested.
    - Lowering pilot/pilot timing really does not help much at all in my testing. The pilot and pilot timing actually helps the atomization a good bit pre warmining the chamber and making the main shot that much more efficient.

    - Cutting post injection (if equipped) indeed will help fuel economy

    - Adding main timing will indeed help fuel economy

    - Having the proper amount of fuel put in with the airflow ready to go early helps economy as it allows less rpms - which if you check out the VE table of these gals boosted - you can see they are very efficient down low.

    Just my 2 cents :-)
    Yes, the goal with that method is to get the timing right for the fuel & air given. Its best to do it at speed and monitor the calc load across the same stretch of road. Even better if a hilly route can be taken at the legal speed limit. I use this technique locally and it gives excellent results. However its only at 1 rpm/speed, once the timing is dialed in I push those numbers up and out to the 2500 rpm range.

    I have also recently concluded that on the '05 piston design I cant get away with dropping cruising RP past ~10.8-11.2k. When dropping it further mpg dropped and stagnated regardless of what was done to the tune. Took a step back to a higher RP tune that gave great results and mpg popped back up.

    On pilot... I cant log timing and have had issues getting good results. gave up on messing with it. HP tuners ticket died with the lockdowns.
    On post... I still have it in play but it is only in a section of the tune used while accelerating and its primary function is to get the turbo spooling.

    FWIW, I've averaged 21.0x mpg over the last 35k miles. Cant complain about that at all. Max was a 25.0x, 5 in the 23's, bunches in the 22's. Tanks is vented so fillups are up to the neck with ease and tanks are always hand calculated.

    Ah, forgot to add... if your gonna be doing 80+, consider a 2nd air dam under the front swaybar (assuming 4wd) to help deflect airflow down past the axle. my truck managed 19.5 mpg doing 85ish thru Idaho with it and 18.5 a year later without the airdam
    .
    Last edited by steve05ram360; 05-13-2020 at 09:32 PM.

  11. #11
    Tuner in Training bluessmax's Avatar
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    Quote Originally Posted by steve05ram360 View Post
    Yes, the goal with that method is to get the timing right for the fuel & air given. Its best to do it at speed and monitor the calc load across the same stretch of road. Even better if a hilly route can be taken at the legal speed limit. I use this technique locally and it gives excellent results. However its only at 1 rpm/speed, once the timing is dialed in I push those numbers up and out to the 2500 rpm range.

    I have also recently concluded that on the '05 piston design I cant get away with dropping cruising RP past ~10.8-11.2k. When dropping it further mpg dropped and stagnated regardless of what was done to the tune. Took a step back to a higher RP tune that gave great results and mpg popped back up.

    On pilot... I cant log timing and have had issues getting good results. gave up on messing with it. HP tuners ticket died with the lockdowns.
    On post... I still have it in play but it is only in a section of the tune used while accelerating and its primary function is to get the turbo spooling.

    FWIW, I've averaged 21.0x mpg over the last 35k miles. Cant complain about that at all. Max was a 25.0x, 5 in the 23's, bunches in the 22's. Tanks is vented so fillups are up to the neck with ease and tanks are always hand calculated.

    Ah, forgot to add... if your gonna be doing 80+, consider a 2nd air dam under the front swaybar (assuming 4wd) to help deflect airflow down past the axle. my truck managed 19.5 mpg doing 85ish thru Idaho with it and 18.5 a year later without the airdam
    .
    Yep! All sounds legit... I'm also a fan of post injection to get the charger spinning - the quicker you can get into efficiency the more valuable energy there is to use!

    When testing fuel efficiency too - I think its pretty important to not change the pulse table from stock or the referenced tq. When these values stay stock - your PIDS will stay pretty dang accurate. When manipulated - it will throw off the factory logic which will then need a correction factor to get the PIDS in reference the fuel/tq to be back accurate.
    Diesels and stuff

  12. #12
    Tuner in Training bluessmax's Avatar
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    Quote Originally Posted by Jim P View Post
    Agreed, other than I?ve found pilot timing to make a very noticeable difference in fuel economy when adjusted and zero difference in fuel economy with post on or off. These engines are very efficient down low but high engine efficiency doesn?t equal high fuel economy. Big difference between engine efficiency and fuel economy.
    I think that is a good topic to discuss..

    High engine efficiency will always trigger back to good fuel economy in my testing. The higher efficiency of the engine - the less energy it is takes to get to the same power. So I suppose that opens up the topic of what we call "Engine Efficiency".

    Example of this - lets use a turbocharger for example..

    While we may be able to maintain lower EGTs and snappier response with a tigher AR (Or tighter vanes) - we can suffer the negative energy that is produced due to the pressure ratio being off. In other words, the engine is having to work harder to get the air out of it due to the backpressure. So the trick there is how to balance the efficiency and what are your goals in this regard. Low boost areas can get their torque back from timing, however, you want the timing to be lower once you get into the area you want to bring the charger in so that way the heat will bring the charger in quicker and you get back to that high efficiency range.

    Tuning is a blast and lots of testing to find the proper balance. I enjoy reading what everyone is doing.
    Diesels and stuff

  13. #13
    Quote Originally Posted by bluessmax View Post
    Yep! All sounds legit... I'm also a fan of post injection to get the charger spinning - the quicker you can get into efficiency the more valuable energy there is to use!

    When testing fuel efficiency too - I think its pretty important to not change the pulse table from stock or the referenced tq. When these values stay stock - your PIDS will stay pretty dang accurate. When manipulated - it will throw off the factory logic which will then need a correction factor to get the PIDS in reference the fuel/tq to be back accurate.
    So some fun fact comments... 2 years ago I was in a bet with a co-worker on whether or not I could get 5 tanks to average 23.0 mpg or better. Had already started a truck makeover that took me back to stock for the most part on the suspension and stock 2012 ram alloys (21# ea) Noticed a change in throttle response and steering effort right off the bat with the wheel change. (still running the original steering pump with 435k on it as of today). At one point during that year I installed an aluminum driveshaft looking for throttle response changes. Others who installed it with the MT said they noticed some change. AT the time my detuned truck was pretty sensitive to changes and immediately I noticed I'd lost spool on the bottom end. What was 1200 rpms for spool to come off ambient pressure then became 1400. I concluded the timing in the cells that was helping to get the spool up and going was not being hit anymore with the slight change in throttle response. So I went back and tweeked the timing in the area where it was accelerating thru and sure enough, spool came back down... and then some. With that Ah Ha moment I tweeked timing further down the rpm range and got spool coming off ambient as low as 900 rpms.

    Now being addicted to the change in the throttle response I was a happy camper. (won the bet btw with a 23.1x averge). Up comes the 100k belt swap for the front of the motor. Came across a smaller fan drive pulley that would allow the belt change to occur without having to pull the original designed fluidampr off. So I jumped on it (aluminum piece), installed it and the first drive there was a noticeable change in throttle response (no mechanical fan for me and remember, detuned for mpg). When I got home (apt living) I searched for any aluminum pulleys out there for the 5.9 motor and found Beans had a set. Needing only the idler pulley at the time I ordered one up. When the install day came it was one CF after another and the excitement dwindled. When it was finally on I was bummed to see the throttle response I'd gained with the fan drive pulley swap now gone. The 1st day driving with it happened to be a road trip to distant go karting facility and along the way I had time to think about what was up. Concluded the bearing in the idler pulley needed some heat cycles in it to loosen up and maybe the lost throttle response might come back. By the end of the day, some of that throttle response was indeed coming back (250 mile day). It all eventually did come back and then some. Not earth shattering but noticeable with my detuned setup.

    Fast forward to 2019... another motorhead decided to drop in an electric water pump. He commented on the throttle response changes on his new setup, which included deleting the fan drive & idler pulleys, was flat out nuts. So after much internal debate on it, I also pulled the trigger and dropped one in. I too noticed even more throttle response changes with the new pump. Leveraging it all, I'd been de-tuning further along the way with the goal to make a reasonable daily driver thats reasonably fuel efficient. That is what led me down the "drop RP" path and see where it goes. The last tank at the start of winter on the tune I just dumped back in gave me 22.8 mpg on winter fuel. All the changes and tweeks after that just dropped me down to a solid 21~21.2 mpg. The driving goal was achieved but the mpg was not where I'd expected it to be. so about a week or so back I went back to that 22.8 mpg tune and dropped it back in. This week mpg popped up some (still running the tank) and its clear by the miles driven vs % of fuel remaining (remember vented tank so a full tank is up to the neck). Granted tanks in the last month have had more city driving than hiway so not quite apples to apples comparison. If things ever get back to "normal" and I am driving daily to work like this week, I'll drop in that last tune with the lowered RP for a rough comparison.

    anyways... fun in the sun...

    Oh and in case anyone is wondering about mods... 50 hp injectors HTT 64mm HE351, AFE exhaust mani, stock downpipe, 30" magnaflow muffler, ATS Arcflo intake elbow, fuel cooler, late G56 with 3.73's on 33" tires. 435k on it, owned it since 13.3k back in 2006. Bought it with an AT, went MT at 225k and fell in love with it all over again.
    Last edited by steve05ram360; 05-14-2020 at 03:31 PM.

  14. #14
    Tuner MAIDENCR's Avatar
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    My tune is dialed up good but will try to get mor mpg from it...now i have 14mpg with a mix of city/rural and beating on it driving....but i should do better i think....my main timing is relatively low and rail pressure high to reduce haze
    Timing is arround 1.7-2.3? btdc
    Rail pressure is arround 15500psi
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