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Old 12-18-2019, 09:52 AM   #1 (permalink)
EcoModding Apprentice
Join Date: Oct 2012
Location: PNW
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Dodge Ram 2500 eco build

Been a while since I posted here so I thought I'd share some results.

Truck is a 2005 Dodge Ram 2500 4x4 QCSB

Short version... gave the truck a make-over starting back in Dec 2017, details of the entire change over can be found here

With all the mods done and all the miles put on it, mpg went from 18-19 mpg in the winter to its current 21-22 mpg

List of changes:
  • e-fans (Volvo's, 2 of them drawing max airflow of 3700+ cfm ea)
  • e-water pump (newly installed, throttle response change noted)
  • lightweight aluminum wheels (2010~2012 OEM, 21# ea, replaces 31# H2's
  • lightweight driveshaft (dropped 13# off the oem, throttle response change noted)
  • aluminum pulleys (dropped 1# off each pulley, throttle response change noted)
  • stock height (removed 2" leveling springs
  • HP Tuner ECM changes (retuned so many times I lost count)

Each time there was a throttle response change, I changed the tune to leverage the throttle response change. Injection pressure has been dropped significantly in the cruise range to bring throttle response back to what it was prior to the changes, meaning I want it to drive like it did the day before I did the swap. Other changes included duration reduction and remapping the throttle table, pilot timing, pilot quantity etc (etc = I forget all that I did).

I took a look at all of the receipts from various years, dumped them all into a spread sheet and averaged it out per year (dont ask for exact numbers, file is not handy). MPG went from ~18.5 mpg up to a solid 20.9xx mpg over a 20k mile window. All of those miles ARE NOT eco drive miles. Many trips included DGAS (Dont Give A ****) where time was important. Lots of tuning during that period as well.

The rest of the mods on the truck include 50 HP injectors, ATS Arcflo intake elbow, modified stock airbox (have an electric exhaust cutout bolted to the bottom of the air box for more air when DGAS tanks are in effect), AFE Torque tube, HTT stage 2.5 turbo (64mm comp wheel & 10 blade turbine), AFE SS exhaust manifold and a 200*f t-stat. Only aero mod on it right now is the 2nd air dam under the swaybar mount, rear tire spats and front wheel liner vents.

Current problem = not being able to get CTs (coolant temps) up to where I want them, the EWP (electric water pump) flows at a steady rate and is pretty good at cooling the motor off. I need to either reduce the current/voltage to it or do a PWM controller for it.

My commute route allows for pretty consistent mpg numbers when driving 100% eco. The sample window is 300~400 miles on eco drives, speeds are capped at ~62 mph, neutral on downgrades when steep enough to support speed, short shifting to leverage all the torque in the 900~1400 rpm range.

Next up, going to look at rail pressure vs mpg, I've gone down the "reduce rail pressure for mpg" path and seem to have hit a ceiling. So, the next path is to experiment with the different rail pressures & reducing the duration. The 04.5-07 pistons have some special design for emissions and I am beginning to wonder if higher rail pressures would help mpg vs hurt. Only way to find out is roll with it and see what I get.

Current odometer = 425K miles

Anyways...there it is... for the next guy looking to mod a 6800# truck for daily driving mpg

Last edited by steve05ram360; 12-18-2019 at 10:14 AM..
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