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I get 22-23 if I keep it between 60 and 65mph. On that same stretch of road my mileage drops to within .5 of 19mpg if I kick it up and keep it between 75 and 80mph on that same stretch of freeway. This freeway is fairly level without many turns so it’s perfect for this type of testing.
 

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Discussion Starter #22
Just a thought, I get the best fuel mileage from my truck when I’m on a long run at an avg speed of 60-65mph. 55 might do better but there’s nowhere that I run this speed at.
I get 22-23 if I keep it between 60 and 65mph. On that same stretch of road my mileage drops to within .5 of 19mpg if I kick it up and keep it between 75 and 80mph on that same stretch of freeway. This freeway is fairly level without many turns so it’s perfect for this type of testing.
Is your truck stock?
 

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I can duplicate that in my truck... its the tune doing it. More efficient at the higher rpms @ 70 than at 60. Last summer on a road trip I managed mid 19's doing 85 across Idaho and into Utah spinning at 2500 rpms. Truck was back to stock suspension wise and had 33" tires. Was pretty happy with the 19's and after the trip, truck ran better.
:surprise:

That's incredible.

I reckon my truck would get mid to high 17s doing that right now.
 

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Stock engine, stock tires, minor lift, and tuning done by me with HPTuners
 

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Conversely I have a lot of good data for the 6.7, including measured in cylinder pressure data.



All Ram Truck based.



I could have used the BSFC map from the 6.7 for the 5.9 but wanted to do better.



Extracting the BSFC data and inputting into the simulation is a pain!



What kind of flow meters did you use? Coriolis type?
Infrared, electro optical

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Infrared, electro optical

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Very cool. Can that be set up to measure petrol flow rates on a gasoline car?

Ive always wanted to have a volumetric efficiency display in in my 1970 Challenger!
 

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Very cool. Can that be set up to measure petrol flow rates on a gasoline car?



Ive always wanted to have a volumetric efficiency display in in my 1970 Challenger!
As long as it's clear or translucent liquid. Cannot be red. I have one on the send and one on return.

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what signal does it provide? digital counter or analog?

I've seen some flow meters on-line that will handle diesel with a counter output. Some of them also come with a display to handle all the conversions.
 

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what signal does it provide? digital counter or analog?

I've seen some flow meters on-line that will handle diesel with a counter output. Some of them also come with a display to handle all the conversions.
Square wave output. I use a omega logger with it.

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what signal does it provide? digital counter or analog?

I've seen some flow meters on-line that will handle diesel with a counter output. Some of them also come with a display to handle all the conversions.
dual post

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Square wave output. I use a omega logger with it.

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Square wave output. I use a omega logger with it.

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I understand... your just trying to get your message across... :grin2:
 

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OK, I cant post pictures right now then, but I can post some of my simulation results.

The take away from my real world fuel economy results is this- On my other cars, normal cars, like Jaguars XJRs, VW Golfs etc- stop start driving usually brings the average fuel economy down and longer distance Highway driving brings the average up.

For the Ram diesel it seems to be the opposite- I think this is because of the immense frontal area of the truck and the poor drag coefficient- that driving it at speed kills the mpg.

FWIW the simulation shows exactly the same trend. It's best not to focus on the exact numbers of the simulation but to utilize it in terms if trends and then compare it to our real world experiences;

So I have

Stock Quad Cab Dodge Ram 2500 with 48RE , 3.73 rear end and 265/70 -17 tyres

Fed Highway sim avg: 20.94 mpg

Stock QC Ram 2500 with NV5600 ,3.73 RAR and 265/70-17

Fed Highway sim avg: 18.49 mpg
My problem with this result is that the Fed Highway doesn't utlise 6th and revs the engine quite high, more so than any driver seeking fuel economy would- so I would like to modify the shift schedule if possible

QC 2500 with 48RE, 285/70-17 tyres and a 3.42 rear end
Fed Highway: 21.35 mpg- Here you can see the effects of both the larger diameter wheels and the 3.42 rear end. I need to separate out the effects



Stock QC 2500 with 3.73 RAR and 265 tyres
running constant 75mph: 12.23 mpg

QC 2500 with NV5600 with 3.42 RAR
running constant 75mph: 13.51 mpg

QC 2500 with 3.42 RAR and 285/70 tyres
running constant 75 mph: 12.98 mpg

I know I need to separate some of these effects out.

Other notable assumptions- I used a drag coefficient of 0.56 as a guess. The SRT10 was 0.45, the stock 1500 is listed as 0.53 so I guessed at 0.56 due to the higher stance and I increased the frontal area accordingly.

I used 88% as average efficiency for the 48RE- most autos ( like the NAG1 Benz trans are low to mid nineties). Because this is derived from an old torqueflite_ assumed a low figure. This is probably a bit harsh of me but I'd rather be pessimistic.
I assumed the efficiency of the NV5600 at around 98% in direct drive top and 97% in 0.73 over drive ratio.

There's quite a lot of 'stop and go' in the Federal Cycle.

This is the cycle-

https://www.dieselnet.com/standards/cycles/hwfet.php

It doesn't really get up above 60 mph- which is why the figures look quite good.

The other factor is that for the BSFC map (break specific fuel consumption) for the 5.9 Cummins I used some measured data from a Semi Truck dyno data I had and some 8 mode test data I had I extrapolated the rest. Also the spec of he semi truck application of this engine isn't EXACTLY the same as the Ram pick up. In addition, when this BSFC data is derived- its steady state on an engine dyno, what a vehicle achieves when driving can be a bit different.
So I did some BSFC curves for part load. My truck ~55MPH, ~1600RPM (G56 w/275/70/18 and 3.73) will be around .588 lb/hp*hr and sip at 13.2 lb/hr of fuel. This is figured at 7 lb/gal of diesel. That puts mileage at 29 1/6 mpg, which is VERY consistent with what I see on an average day on flat ground @ 55MPH. So that's approximately 22.5 WHP to move down the road @ 55MPH.
Math for 65MPH @ ~1900RPM
lb/hp*hr = .495242
lb/hr = 20.188
MPG=24.27
WHP Required=40.76

The mileage is VERY consistent again to what I see in real world with MY truck.

Just throwing the numbers out there to you and maybe that will help with some other numbers you may not be finding.
 

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I used .52 as Drag coefficient and 35.1 ft2 for my hp numbers so by changing to yours my BSFC numbers go wack and won't line up with the real world.
 

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My city mileage for the last 6 months was 18.69MPG over 6020 miles with about 600-700 of those miles being highway. Figured I would throw the mileage in for winter city as I finally started using technology to track mileage rather a pen and paper.
 

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My city mileage for the last 6 months was 18.69MPG over 6020 miles with about 600-700 of those miles being highway. Figured I would throw the mileage in for winter city as I finally started using technology to track mileage rather a pen and paper.
Thats weak dude... Weak....lol

I think your truck would like a fun road trip more often...:grin2:
 

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Thats weak dude... Weak....lol



I think your truck would like a fun road trip more often...:grin2:
Yes, it's horrible, but that is only those data collection points. I'm probably around 18k total miles for the last 6 months.... winter is maintenance time for me, spring, summer fall are my driving seasons

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If you want to reach for low hanging MPG fruit, built trans and 15SS converter from goerend. Low stall converter will be worth at least 0.5 mpg at any time.

Another thing to look into is the firepunk Anteater. It allows full control of the transmission. Much better than the files that are within the ECM actually.. lock in second, or on the 1-2 shift and then keep it locked. Plus you can have 3 shift profiles to choose from. I'm almost to the point of getting one myself.

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For all the pictures you could ever want to post. use imgur.com. upload your pics there, click on the pic you want to use then copy the bbcode. go to your thread post and paste the copied bbcode into the post and you have pictures.
 
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If you want to reach for low hanging MPG fruit, built trans and 15SS converter from goerend. Low stall converter will be worth at least 0.5 mpg at any time.

Another thing to look into is the firepunk Anteater. It allows full control of the transmission. Much better than the files that are within the ECM actually.. lock in second, or on the 1-2 shift and then keep it locked. Plus you can have 3 shift profiles to choose from. I'm almost to the point of getting one myself.

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For mileage, I would stay far from an auto. Another thing is having a low stall in the city (unless you switch to neutral at every light and stop sign) will cause you to eat up more fuel. Look at your fuel usage in park (engine temps to operating) and then in drive, I promise you'll realize a double to triple usage unless you have the ability like newer cars to completely disengage the TC at a stop while in drive. Datalogs have shown me that an automatic (factory) will use slightly more fuel at a stop than what it takes my truck to do 55MPH.

Example:

Manual manual uses 7.5mm3 of fuel to idle per injection while at light and stopped. Uses approximately 25mm3 to run 55MPH.

Auto pickup uses 28mm3 of fuel to idle per injection while at light and stopped while in drive. Uses approximately 30mm3 to run 55MPH

This is based on both trucks that have exact same tune with factory parts. They also use more fuel while TC is unlocked to accelerate and they always take HP to drive the pump. You can do a lot of mods to an auto and the ones that get better mileage on the highway will hurt you in the city or even just normal use. These reasons are typically why manuals get about 1-2MPG better under similar circumstances and same effective drive ratio. I'm not saying your mods didn't help you in mileage, I'm just painting a picture that what you see is due to your usage and could vastly change the other way for somebody else.
 

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I understand the perfect transmission doesnt exist for these trucks. The OP just stated he was saving for firepunk setup. Wanted to give him some potentially useful insight is all.

The ideal transmission is an auto, and does have a neutral clutch for every time the vehicle stops. Locking the TC upon the first shift.

I was aware that autos in gear use a lot more fuel than just idling in neutral, I've always thought that was a way to save a lot of fuel. In neutral my CTS2 shows 0% load, in drive sitting still, it shows 5%.

Back draining the torque converter at a stop would lessen the load dramatically, but that would be like driving a space shuttle at that point. Your truck would be impossible to drive for anyone else.

So many things about transmissions to gain and you see it in modern cars. They gain more efficiency from playing with the TCM than with the ECM. Fact.

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