2005 Cummins 60HP Tow Tune - Help with Fuel Economy w/ Raised Rail Pressure Targets

Hey Guys,

I hunted through 40 pages on here scoping out some solid advice from Jim P and so many others, so I finally decided to make my first post on here and get some advice.

We have a low mileage (102k!) 2005 Dodge Ram 3500 Dually with Stock Turbo (I made a custom 6466 Non-Wastegated GTX55 based Ball Bearing setup that didn't work out).

What I am trying to accomplish here is the use of higher base fuel pressure in cruise and shorter pulsewidth to make a very clean, very cold tow tune for this truck. I'm towing a 2022 Grand Design 303RLS and currently the truck is doing fantastic with it; just seeing if there's more on the table in regards to efficiency.

Let's go over what's on it and what I've accomplished so far.

Banks Economind
Banks Intake w/ Superscoop
Banks Exhaust Brake
Built 48RE
265/75R17 Front, 235/80R17 Rear (Dually) inflated to 65psi F and 60psi R respectively.

Currently the truck is on ModFan5 tune (attached) and will do 1320F peak EGT, but sustained will be 1000-1250F at 40psi.
Cruising unloaded will average 20.5-21.5mpg.
Towing will be 10 (steep mountain grade) to 13mpg respectively.
The reason why it's called ModFans is the 195F starting temp, 215F max fan speed settings for Coolant and Transmission Temp. The Mishimoto Transmission cooler bypass insert is coming in the mail this week as mine didn't have it, and the thermostat isn't keeping up.

While I know these are pretty average figures, I thought it would be great to hear the advice from actual diesel tuners like yourselves and see if we can target near peak CP3 pressure figures down low, cut short the injection timing (currently set stock), and let it eat.

On ModFans6 I used the Tony Pinto calculator at 50/50 settings to produce a new timing curve as well. This is the file with the fuel pressure target changes, which I have yet to test.

What do you guys think about these two maps? Where do I go from here?

Cheers,

-Ryan


Attachment 149910

Attachment 149911

You are far better off datalogging where in the map you are operating at on the tables and make small adjustments up and down on timing to find where it needs to be, the so called timing calculators and 50/50 split is just not how it works. What you are theoretically wanting to aim for is the cylinder peak pressure during the combustion event to be around 2 degrees after top dead center and a 50/50 split on your injection event doesn’t give that as many variables effect where your peak cylinder pressure occurs like ambient temperature, injection pressure, fuel temperature, coolant temperature, intake airflow, intake air temperature, altitude, pilot injection event, list goes on and on and without a head fitted with pressure transducers you won’t achieve the target of peak pressure being 2 degrees after top dead center. Honestly 50/50 timing split isn’t even a good starting point. Look at stock and in the cruise region it’s in the 300+% before top dead center. Map out where you are operating and make small adjustments up and down to find what’s best in the operating regions and blend the rest into that.

Quote:

---

Originally Posted by Jim P 2.0

You are far better off datalogging where in the map you are operating at on the tables and make small adjustments up and down on timing to find where it needs to be, the so called timing calculators and 50/50 split is just not how it works. What you are theoretically wanting to aim for is the cylinder peak pressure during the combustion event to be around 2 degrees after top dead center and a 50/50 split on your injection event doesn?t give that as many variables effect where your peak cylinder pressure occurs like ambient temperature, injection pressure, fuel temperature, coolant temperature, intake airflow, intake air temperature, altitude, pilot injection event, list goes on and on and without a head fitted with pressure transducers you won?t achieve the target of peak pressure being 2 degrees after top dead center. Honestly 50/50 timing split isn?t even a good starting point. Look at stock and in the cruise region it?s in the 300+% before top dead center. Map out where you are operating and make small adjustments up and down to find what?s best in the operating regions and blend the rest into that.

---

I appreciate the insight there, Jim.

Moreso, what I am trying to figure out here is optimization of fuel economy by means of higher injection pressure.

Maybe I should setup a calculation to have the following:

OEM Injection Pressure x Injector Deadtime (or Injection Time for Diesels apparently) = Given Fuel Flow for an OEM Application.

Raised Injection Pressure x Modified (Lower) Injector Deadtime = Matched Fuel Flow for OEM Application.

Should be an extremely simple calculation to allow me to reduce the injection time and match the total fuel flow, which in theory should drop EGTs and improve cruising MPG.

*Note* Original Thread was missing the cruising unloaded EGT of 600-700F, and loaded 800-900F.

What sort of miracle work have you guys done for Fuel Economy?

Cheers,

-Ryan

I wouldn’t complicate it with trying to derive formulas and stuff, it’s just complicating it more than it needs to be. Your fuel economy isn’t horrible either for the model year, it’s pretty good actually, you’ll be pretty hard pressed to get much more out of it. I would just start with a good datalog to see where in the tables you are operating at for a specific vehicle speed and start with timing, little adjustments up or down till you get what you can out of it then you can say bump up rail pressure a little bit in that region and go back to timing and make little adjustments up or down to see if you can get further improvement. It’s just a time consuming process of little adjustments and logging till you get to where you want to be. Like I said though your fuel economy for that model year isn’t bad at all and you’d be hard pressed to get much more out of it and keep in mind external factors like head wind, tail wind, hotter day, cooler day, things like that are going to through things all over the place. You could get more complex with it by using the modifier tables to try to account for different ambient air temperatures but things like head wind, there’s just nothing you can do about it, it’s just going to pull down fuel economy, think of the surface area and mass you are trying to push through strong head winds, it’s going to take more work to push through it.

It would be pretty cool to try something like this out, so I'll see if a buddy is comfortable making me an Excel Spreadsheet for what I'm talking about above to spit out calculated, reduced "Modified Injection Time" to spit out something that matches the new raised CP3 rail pressure.

Downsides:
CP3 is run harder.
Injectors are run harder.

Upsides:
Bosch built all of this stuff for 30000psi Sustained
Sensor stops reading around 24500psi for this year.
Later trucks all ran higher rail pressure for a reason.

Well it’s more complicated than just that and it’s just making it even more complicated for what, to make it more complicated? The rail pressure relief valve is only good for about 180-190 mPa but you don’t want to run that kind of pressure in cruise region. Tuning shops that have been around tuning those trucks since custom tuning became available for them don’t use timing calculators or excel sheets with formulas to adjust pulsewidth because rail pressure was turned up a bit in a specific spot. They adjust as described above to figure out what’s best what isn’t what works what doesn’t. Your pulsewidth table is the flow characteristics of the injectors, like it’s all tested and measured and inputted into that table. So when you change rail pressure somewhere in the table, it already adjusts your pulsewidth time for the given estimated fuel flow and pressure measured. Unless you are running oversized injectors there isn’t any need to start adjusting the entire pulsewidth table, it doesn’t make sense. The upper end of the pulsewidth table maybe adjust on stock injectors to get more power out of it but there really isn’t anything to facilitate the need to start changing that table everywhere based off of adjusting the rail pressure table.

Even injector latency is already programmed into the ecm and the control algorithm uses it in its calculations. I mean if you want to go through spending a lot of time on something that makes no sense, I mean you are of course free to do so but you really don’t need to.

The purpose of having a target rail pressure increased in towing regions is to drop EGTs further since the injection event is now shorter and should produce a cleaner exhaust as a result. This then allows me to run slightly more power to now match where it was previously and should return with better fuel economy.

Example: 1800 RPM, 4th Gear, 62mph, 900F EGT. Let's say the truck is producing 200hp/300tq to maintain this speed here and fuel consumption is 13mpg.

If we shorten that injection event and EGTs drop an additional 50-100F, I can either run it at 800-850F, OR I can choose to increase power output at that same location maybe up to 240hp/350tq to hit the same 900F EGT. What this should end up doing is resulting in less pedal to maintain speed and fuel economy should increase as a result of that.

See what I mean?

If you say so

I’ll just say expectations versus reality are two different things and like I had previously said, you’ll be super hard pressed to get much more in terms of fuel economy on that model year unless you can turn pro at that hypermiling stuff, axe a lot of weight from the truck and improve it’s aerodynamics.

Quote:

---

Originally Posted by Jim P 2.0

I’ll just say expectations versus reality are two different things and like I had previously said, you’ll be super hard pressed to get much more in terms of fuel economy on that model year unless you can turn pro at that hypermiling stuff, axe a lot of weight from the truck and improve it’s aerodynamics.

---

I took your advice on the 12-14k PSI rail pressure at cruise cells and nerfed a bunch of power between 1400-2000 RPM (due to the 4.10 Gearset). Swept the rail pressure up to 26.5k in the high load and high RPM sections and smoothed everything out.

My only question left over is if you could overview the Fuel Timing on the Mod5 file attached above and give me some insight to better shaping/targets.

The truck drives incredibly smooth and has this "tame until you want it" feel, which I believe is resulting in the fuel economy that it just showed. Mod6 was terrible due to other control strategies implemented and giving me full power off of idle and unnecessary smoke, even if peak power is about the same as it is now.

On version #8 of this, so there's been a lot of refinement since these two posted files.

Much appreciated, Jim. Thank you for everything.

Attachment 150325

So that ModFans8 file that I spoke of in my last post came out REALLY clean, drives beautifully well, and does have an improved gas mileage over stock.

What I'm doing now is ramping power back in in hopes to hit 1300-1350F EGT peak, 1000F or so sustained. This 1227F was pouring on throttle HARD, far past the speed limit and is too far detuned for the goals of hauling this 5th Wheel with a bit more gusto.

New file has:

Torque Converter TCC Lockup Changes
More Fuel Max Allowable Fuel from 1600 RPM to 2100 RPM
More Total Injector Mapping
Advanced Timing using Tony's 50/50 Calculator

Excited to show you guys the results tonight/tomorrow.

Attachment 150418

Four tunes later and I landed on this with:

A perfect shifting transmission and TCC lockup/unlock settings.
Top End with timing changes feels incredible.
Fuel Economy is up everywhere.
Peak CP3 Pressures are 25k with an average of 5% bump over OEM everywhere.
Max Injector Duration is around 2400uS.

All I'm trying to do now is chip away at the 1600-2000 RPM tow range (where I made things more efficient, slightly less powerful), and see if there's a better balance to be had there in either direction.

Small note for anyone using a built 48RE w/ Triple Disc Torque Converter; the 4th Gear Output Shaft Speed to shift a 4:10 Gearset is roughly 2150 RPM at 52mph which will make things buttery, and THIS made a world of a difference.

Attachment 150421

Well, this trip got expensive.

Either a failed injector (rev hang before we left) or bad diesel, but it just required us to change things up.

Melted Cylinder #5 and fuel economy was better than ever towing. 13.5mpg on sweeping grades up Highway 101.

The new DFC Longblock has the following mods added to it:

Hamilton 103lb Valve Springs
Hamilton Pushrods
Hamilton Tow Cam
DDP +15% 50HP Injectors with Pilot Hole Technology
ARP Headstuds

Current fuel economy on detuned version of last tune is 14.5mpg unloaded and 8mpg loaded.

It's not my truck anymore... Gutless and breaking in.

Not sure what to do right now or if this horrible efficiency is just due to break in.

Alright, things are going to move forward here with some smarter stuff, so I'll elaborate.

First off, a drop-in BorgWarner S364SX-R with 0.80 A/R T3 Divided, non-wastegate.

MatchBot Specs here:
https://www.borgwarner.com/go/ZS0B8K

Attachment 152103
Attachment 152104
Attachment 152105
Attachment 152106

Attachment 152109

Next up is an Exergy 2200 Bar Relief Valve and higher rail pressure sensor.
Industrial Injection Bag of Parts.

At this point, we are optimizing the hell out of this system like how it was with the OEM Injectors and OEM Turbo, just upsized to handle the task of Cascade Mountain Range and our REAL West Coast grades.

I'll be reporting back with fuel economy and upgrades as I get things sorted and installed.

Cheers.

Quote:

---

Originally Posted by RGHTBrainDesign

Industrial Injection Bag of Parts

---

Just a high recommendation, spend the money and get an Exergy or S&S 10mm pump, don’t waste time on a bag of parts and don’t waste money on anything Industrial Injection

Have you done any tuning with the new turbo?

Quote:

---

Originally Posted by Noah

Have you done any tuning with the new turbo?

---

Yes.

Right now the truck is the best it's ever been.

Still balancing the Timing and Total Fueling, but the break-in period is mostly done and truck has started to balance out really well at 2500mi.

Attachment 155534

Attachment 155536

Attachment 155535

So previous mapping had this timing and towing was the best it's been since the new block. I thought it was slightly over-timed as temps were excessively low for how the rest is mapped.

Previous Timing and Difference

Attachment 155537

Attachment 155538

Really stoked to see the difference I've made on MY tuning vs. a stock tune for these injectors.

The more experienced folks like Jim will notice quite a high Injector Pulsewidth Deadtime table and this is in attempts to "fool" the ECU into running the engine leaner with the larger injectors. Getting this curve to shape properly for a faster injector took about 80x tries to get solid... Yeah, that was a lot of time.

The lie-o-meter shows a significant bump in fuel economy which is so far proving to be pretty good. Towing about 2.5hrs I used about 1/3rd of a tank going over grades and to the ocean. I'd suspect the shown 13mpg to be close.

Hamilton Cam + S364SX-R in the stock 5.9 is a really nice combo for everything and I haven't felt the need to really be "on it", ever.

Tonight's homework is going over a 60HP Tune file that I purchased and comparing timing to where I was at for these last two files. The last thing I want is to have this thing burning up a piston by latent heat in the piston region vs. out the exhaust.

Let me know what you guys think.

The Hamilton cams really make a difference, would love to put one in my 2012 one day

Quote:

---

Originally Posted by RGHTBrainDesign

Yes.

Right now the truck is the best it's ever been.

Still balancing the Timing and Total Fueling, but the break-in period is mostly done and truck has started to balance out really well at 2500mi.

Attachment 155534

Attachment 155536

Attachment 155535

So previous mapping had this timing and towing was the best it's been since the new block. I thought it was slightly over-timed as temps were excessively low for how the rest is mapped.

Previous Timing and Difference

Attachment 155537

Attachment 155538

Really stoked to see the difference I've made on MY tuning vs. a stock tune for these injectors.

The more experienced folks like Jim will notice quite a high Injector Pulsewidth Deadtime table and this is in attempts to "fool" the ECU into running the engine leaner with the larger injectors. Getting this curve to shape properly for a faster injector took about 80x tries to get solid... Yeah, that was a lot of time.

The lie-o-meter shows a significant bump in fuel economy which is so far proving to be pretty good. Towing about 2.5hrs I used about 1/3rd of a tank going over grades and to the ocean. I'd suspect the shown 13mpg to be close.

Hamilton Cam + S364SX-R in the stock 5.9 is a really nice combo for everything and I haven't felt the need to really be "on it", ever.

Tonight's homework is going over a 60HP Tune file that I purchased and comparing timing to where I was at for these last two files. The last thing I want is to have this thing burning up a piston by latent heat in the piston region vs. out the exhaust.

Let me know what you guys think.

---

Do you have a new tune file you would not mind sharing? Just getting some ideas.