Join Date: Apr 2019
Location: Mid West
Thanked 0 Times in 0 Posts
iTrader Score: 0 reviews
New Ram Cummins- and long distance running
First I'd like to say I'm happy to be a part of this community. The FB groups can get down right nasty and abusive, but I've been observing here and everyone seems to be quite nice so far.
I bought my 2005 Dodge Ram 2500 Cummins last year, and it saved me from spending a whole load of money on a new F250.
I wanted to get a truck before all the emissions complications.
I was in Arizona on business and couldn't believe the condition of the body. Amazing.
Brought it back up north, got it ziebarted.
With 185 K miles on it I knew The trans and the injectors were the issues I'd have to watch. Saving up for a firepunk reinforced trans, I had a sticking-injector-run away incident.
Anyway, injectors have been changed for ones tailored to my specs. 8 holes, hydro ground and matched holes.
More on my injector choice in another thread.
Until I reinforce the trans I'm not doing anything silly in terms of power, so I decided to focus on fuel economy.
I've been remapping the ECU myself using HP Tuners.
First, a little about me, I'm an vehicle and powertrain development engineer. I've been involved in several automotive, light , medium and heavy duty diesels as well as the development of petrol engines also.
It's still an iterative process.
In a nutshell, I upped the rail pressure at the appropriate duty cycle load points, advanced the injection timing (its quite obvious looking at the 05 cummins maps and piston bowl design (a shallow bowl rather thana re-enterant-2-step bowl), a very high priority was given to lowering NOx emissions without using external EGR and/or aftertreatment at the expense of engine efficiency).
I also messed with throttle progression, and closed up the injection pulse widths to compensate for my injectors.
I got 19.95 mpg driving down from Chicagoland to Indiana, some in heavy traffic,
Then 20.67 mpg, heavy traffic and slower highway speeds.
Then up to Minnesota- 19.44 mpg (going pretty fast, not hanging about- really giving it some!)
Worst I got, "not hanging around"- was 18.4 mpg.
I plugged in some of the 3rd Gen particulars into my simulation package. Simulation alone is dangerous, but when done in league with real world- it really allows good understanding of whats going on:
Now, I put my simulation through the Federal Highway Test.
You will see a 48RE ram vs a NV5600. 1st pic is with NV5600, second is 48RE and third shows a 48RE with a hypothetical 3.42 rear end and my bigger tyres (stock diameter is 31.6 inches, my 285/7- R 17s are apparently 32.7 inches diam). The problem I have with the Federal test is that they don't change up to 6th on the NV5600. Nevertheless, the test is more representative of the driving I did in Chicagoland in some traffic and then going down to Indiana.
It also shows that with a 3.42 rear end, the engine operates at higher load, where it runs more efficiently, better 'BSFC' or brake specific fuel consumption.
The pics show where the Ram 'sits' on the engine speed map and therefore the best place to concentrate when re-optimizing the map for best bang for buck. A Ram 2500 probably uses about just under 100 Bhp to maintain 75 mph. Compare that to the 37 bhp or so to push a 2000 model year Jaguar XJR through the air.
This is why slower traffic runs, even with some stop and go traffic are often better in terms of mpg than constant 75 mph runs.
Last edited by Marquis Rex; 04-08-2019 at 12:14 PM.
Reason: Unable to upload the pictures