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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

https://www.cumminsforum.com/forum/3...-makeover.html

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

Looks like it's time for aero mods.
You will likely have a few simple aero mods giving more mpg boost on the highway than all of the mechanical ones.

Quote:

Originally Posted by oil pan 4 (Post 613534)

Looks like it's time for aero mods.
You will likely have a few simple aero mods giving more mpg boost on the highway than all of the mechanical ones.

The only ones I'd consider would be the bed seals, bumper insert (had those previously) and then some underneath. It has a sliding tonneau cover & tailgate spoiler (off the 1500's).

I know about going all out on the belly pan & whatnot but thats not practical for the use cases...

What would your suggestions be? Considering a piece attached to the trans cross member to divert air down below the axle. needs testing for sure.

Probably a partial grill block for winter since you said the engine is not getting warm enough.
An air dam, how high or how low it goes is up to you.
GM claimed on their 2000s trucks that came with a factory tonneu cover increased fuel economy 6% on the highway.
Ford claimed that on their 2000s trucks that going from a 75mm chin spoiler or air dam to a 100mm air dam chin spoiler increased fuel economy by 1.5%.
When I put a 7 inch air dam on my suburban it was good for at least 1 full mpg no more than 1.5mpg.

Thereare also plug in heaters, block heaters and coolant warmers.

Go with PWM for the water pump.

Coolant temps too low should be an indicator of your thermostat, which should continue to recirculate the water until it hits the desired temp. Unless you have a crazy big oil cooler on it. Do you have a controller on the electric fans?

Auto transmission or stick?

Your best results would be from a sloped aero bed cover, on my old truck for a while I had a partial bed cover that only was from the cab back the first couple feet. It really didn't impact usability much, but I got a 5% MPG boost. Spats out of conveyor belt in front of the front tires would also help out.

What's your final gear ratio?

That Cummins can live with a staggeringly low (numerically) ratio.

My 7.3 Powerstroke thrives of (3.08 x 0.8 =) 2.45:1 plus the ZF6-550's overdrive gear.

Low gear ratios are very potent for diesels.

Quote:

Originally Posted by aardvarcus (Post 613585)

T-stat is a 200*f stat, if I kick the fans on at 205*f it will drop temps all the way down to 192~194ish, if the fans kick off then it will cycle like that. There is just not enough heat coming out of the motor under normal conditions. I see the temp swings when going up a hill. T-stat is fine.

trans is a manual.

fans are controlled by a hayden radiator probe controller. Cheap, variable and easily disconnected for tune downloads.

Quote:

Originally Posted by Big Dave (Post 613626)

Not sure what the final GR is, gearing is 3.73's with the late G56 which has the preferred gearing. Last time I chatted with Skyking he had the same trans but 3.42's with 2 sets of tires. He mentioned recently he was able to get 25's but did not answer my question about the tires. (34's or 31's) I drove his truck back then, not bad but on a stock tune, it did not sit well with me. Seemed like a lot of throttle to get going and I would expect the hills would kill his mpg.

The way the truck is now with the light weight parts and the huge overall bump in throttle response, it would be way better. Still are faced with the grades everyday on the way to work. As of now, fueling is dialed back significantly to tone down that throttle response change and it still has room to be dialed back. Dialing back = dropping rail pressure & adusting timing, then trimming duration to cut smoke output.