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

[RGHTBrainDesign]

Once I adapted some changes into the new mapping, got on her hard and tuned out the smoke limit and main pulsewidth table at WOT, the truck really stood out as stellar.

I have a 5% Over on the Higher Commanded Rail Pressure, which may result in fuel being dropped into the piston improperly. This is pretty close to how injection timing works for reciprocating 4-Stroke Gasoline engines and by having it too high or too low will result in less than stellar efficiency.

I'll likely move this back and advance timing a little bit under 2000 RPM and move rail pressure to stock.

Really think this came out nicely.

Pilot Timing and Injection is set to 0 at 2600 RPM and big load, so that may benefit from the stock setting as well. I found on these DDP 50HP (15% Over) Injectors, they preferred 0.75x on the Stock Pilot Injection Amount to really clean up and sound super smooth. This is likely due to the new DDP Pilot Tip Design.

[RGHTBrainDesign]

Really honed things in. Truck is happy just like it was waaaaaay back when on the old 5.9 Block on stock injectors.

[RGHTBrainDesign]

https://www.youtube.com/watch?v=lMjw0Zcd8-A

The time has come.

[RGHTBrainDesign]

Final steps now are dialing in the CP3 and the main SOI and pilot timing for spool region to optimize for this turbo. This truck has truly turned into a gem to drive and I have a feeling the towing will be exceptional once we load her up again. By increasing Duty Cycle even 10% in this CP3 Commanded Duty Cycle, I was immediately able to remove smoke and increase pulsewidth from 1679uS to 1850uS with nothing but gains.

Just tuned a local truck here and posted it on my Instagram: https://www.instagram.com/p/DGfSQlcR0LE/

"Really getting the hang of this Diesel Tuning.

Art's 2004 gave me the information I needed to dial in all 3rd Gen stuff for clean power, both 2003-04.5 and 2004.5-2007 5.9Ls.

Fuel Economy
Power
Response
Quieter Operation (Pilot Timing Optimization)

It's crazy to me how well the trucks wake up with tuning and minor mods.

Today I stumbled on High Pressure Pump Fuel Pressure Commanded Duty Cycle (for controlling the CP3 better) and a slight reshape nearly ironed out the pressure command vs. pressure actual delay with very minimal over/undershoot (within 200psi).

To dial in a high pressure fuel pump, you can either do this table (labeled as Fuel Pressure Regulator Base Duty Cycle) or offset the table via the Duty Cycle to Current Conversion table. Both should not be edited as one is a 3D table and the other is a multiplier scalar and they work off of each other.

Easier Route = mA adjustments on scalar table to ramp CP3 in faster. If unplugged, CP3 goes to 0mA which maximizes the duty cycle at 71% (by default). Lowering the values in this table will ramp the CP3 pressure in faster, but too much and you'll overshoot pressure and run into the PID control which will oscillate the pump's pressure.

Longer Route = Mapping Duty Cycle for Fuel Volume (mm3) vs. Engine Speed on a 3D table and leaving the mA conversion table alone. What this does better is allows for any RPM/Volume region to be pinpointed for better response from commanded to actual rail pressure without a global change that could effect drivability.

The amount of information I can cover on diesels these days blows my mind and I'll be revealing more of this soon."

Excited to see where this takes me career-wise, as I've really enjoyed doing engine calibration for years now on Rotary Engines and have a vast range of EFI expertise, but Diesels were a new/fun hurdle that I am glad to add to my toolbox.

Another side-note, the BorgWarner S258SX-R with a 0.83 A/R Turbine Housing will be one of the most capable towing turbos ever placed on these engines. Let me explain...

S258SX-R Compressor Map.png

Considering most of run around 40psi of Boost, you'll be looking at PR 3.75 if you live at Sea Level.

Going through simple math for the compressor mapping, you'll see the following:

S258SX-R Surge Line at PR 3.75 is Starts us at 33lbs/min of Airflow and then carries out to 68% Efficiency (before we start pumping hot air --- note, the turbo will do significantly more than this here) at 67lbs/min. This gives us a powerband WIDTH of 34lbs/min and a total power capability of roughly 8lb/min per horsepower for a 5.9L Common Rail, or roughly 536hp worth of air before pumping out hot and inefficiently. By maxing the turbo out we will see 74lbs/min before reaching redline shaft speeds for the turbo, but we'll be able to produce 592hp. It's hard to put this into perspective, but you'd have better response than a Stock HE351CW, no surge of turbo, and power capabilities over 100whp over stock with a better drive ratio. This is the turbo you want if GRUNT is your game and you want to run a S368SX-R over it in a compound setup. The nastiest tow spec I could come up with and it's compact!

Modern turbos change the game up for everything.

[RGHTBrainDesign]

Screenshot 2025-02-26 183014.png

The truck is almost perfect now.

Just adjusting my CP3 Fuel Volume vs. Engine Speed Duty Cycle 3D Table to optimize engine response and hit targets.

Off Idle there's as much as a 3000psi difference, so that's where I'll feel response the best at 10mm^3 and off of idle (those DC % Values will be increased next revision).
Really crispy at 1800 RPM and within 200psi (perfect/within tolerance).
Slight refinement needed at 2500 RPM breakpoint, but nothing more than a couple percent.
Fuel Pressure at CP3 is DROPPING by Redline by about 1500psi, so that will require higher Duty Cycle there as well.

I put together the new offset blend and we'll see what these estimated values end up with. Glad that at least the most driven region (1800 RPM) is dead to nuts dialed.

Getting rid of delay this way vs. mA Current Conversion Scalar should net me with better engine response and less likelihood to have any PID engaged or oscillation.

As a reminder to myself, I'll be logging mA Current Conversion values for next time to see where I'm at in terms of total flow.

Motorsports Diesel Stroker CP3 is on the way in the scenario I am actually out of fuel; but that would indicate almost 600hp worth of fuel flowing through the engine, which I don't think is the case. This is a BRAND NEW Cummins OEM Pump after all...

For this iteration, I dialed in fuel and timing for what I think will be needed for our ~14000lb 5th Wheel setup and then left a good bit of fueling overhead past 100mm^3 to get us out of trouble if anything wild arises. Not wild like heavy rollin' coal, but definitely noticeable, moderate smoke level in the scenario we need the extra power for emergency.

On this new engine, I don't think I'll ever forget the first drive ever going up Hwy 199 after leaving Brookings, and over Siskiyou Pass in Oregon and how we effectively had ZERO overhead for power, losing speed everywhere, sub-6mpg, etc. Stock Tune + New Engine + 50HP Injectors was NOT the business and we were anemic on power to say the least. Hot (1300F Sustained for a LONG time), smoky, and gutless.

The result of that however has given me depth of insight into calibrating these engines and has paid in dividends. Now I can rest assured knowing our truck will tow flawlessly and efficiently again without being a turd.

[RGHTBrainDesign]

So here's the timing shape that I'm finding works best for aftermarket injectors with a higher pressure "pop" rate.

MainSOI Final.png
MainSOI Final2.png

Same Main SOI table, just two different angles.

[JaegerWrenching]

This isn't bad but it looks a little like a gas tuner learning to tune a diesel lol. There is room for improvement on the overall shape but not too bad! Do you have a dyno to play on? If so Play with the whole 140-100mm3 lower rpm ramping into the higher rpm,. Also high RPM low injection quantity, you can start raising it back up on the 3400-2800RPM rows starting at 40ish mm3 going all the way to 0mm3. It should look kinda V shaped, but you won't see a huge improvement as it's low fuel quantity, but it does help smooth up higher rpm tipout. Also depending on how you have your multipliers set, if you are setting all the timing maps or modes to the exact same values there is for sure a decent bit left in overall driveability when going through different elevations. Also, I saw a post of yours talking about pilot timing where you said if you advance your main 8* then you'd subtract the pilot 8. IDK if you still believe that or not... but that would be true "if" the pilot was set based off the main or what's known as interval timing. However the pilot is set based on TDC, therefore you'd actually advance pilot 8* instead of subtract it if you wanted to maintain the factory split... I also think but maybe wrong, that you believe the lower the EGT the better at all times. This is true for pure efficiency but it can start to lie to you as well. If you over advance injection you could have it try to turn the engine backwards "torque loss" and that simultaneously gives more time for the combustion heat to be absorbed onto the pistons, cylinder head, and cylinder walls. So your EGT probe would read lower... but your coolant temps would start getting higher... Lower EGT can also slow spool and thus the ability to make more torque sooner. You'll sacrifice some initial torque on tipin but make it up quickly, think of a linear line vs a exponential curve, linear wins at first but exponential wins a little later. Especially with modern turbos that once they start to light they boogie and that lets you add a lot of fuel very quickly! That is why I believe diesel tuning is, and will forever be very subjective, it's also why there isn't one diesel tuner who is the "best". Especially when it comes to decently modified trucks, if you are not spending time tuning them in person there is probably a decent bit left on the table...

[RGHTBrainDesign]

This is GREAT insight. Would you be able to snag me some similar photos of what you mean in regards to what you've found to be ideal Main SOI Tuning?

While this isn't the "final" of where I've landed at, it's pretty darn good and this truck has impressed everyone locally with fuel economy, response, and drivability.

At the end of the day, it's setup to tow a pretty heavy 5th Wheel and the way it lights off the S364SX-R is great.

More on the table? Definitely, but I am aiming for safety and reliability for another 150k Miles before changing injectors or anything else again.

Dyno? I mean, there's probably a dozen of them within a 20 mile radius, but nothing the Dually would set well on, I don't think.

The angle was hard to tell, but I already had the shape you described for 2800 RPM to 3400 RPM at 0mm3 to 40mm3. Kinda, at least.

Main SOI S364SX-R v.4.png

The front blending from 100-140mm3 I think you mean sort of like this. Makes a LOT of sense. Great observation.

Main SOI S364SX-R v.4 2.png

The truck runs super clean and has been 1000x better than any of the "paid" tunes I've deal with. I think these injectors needed quite a bit more timing to handle the pop pressure, which I'll give feedback back to Lenny for his other tuners.

Definitely a Rotary Engine Tuner, so I'm used to weird, oddball, unique stuff like this and sorting out issues by vehicle feel; then working backwards.

[RGHTBrainDesign]

Main SOI S364SX-R Josh.png

My buddy Josh (who is world class in everything he touches) sent me something like this to work off of.

Definitely more of the exponential power vs. linear power style building that JaegerWrenching is talking about, but this doesn't quite have a spool region either.

I'll try this out as a "last shot" and see if I like it. I can always go back.

[JaegerWrenching]

Main SOI S364SX-R Josh.png

My buddy Josh (who is world class in everything he touches) sent me something like this to work off of.

Definitely more of the exponential power vs. linear power style building that JaegerWrenching is talking about, but this doesn't quite have a spool region either.

I'll try this out as a "last shot" and see if I like it. I can always go back.

This or Josh's shape looks good, and you can see the V on the high rpm rows, they start going back up around 30mm3. As for high mm3 low rpm or "spool area" you really need to play with it, each truck is a little different and likes different things. Also if your boost limiter is in play and you're ridding the limiter dial that in and see where you're actually operating timing wise. But your ramp in should be more exponential than linear like josh's map shows. If you look at pic#2 of yours to the left of your hill in should flatten out some, maybe even be slightly bowl shaped. This is why I asked if you had access to a dyno. It really helps make repeatable runs in dialing this in. The lazier the turbo the more timing it'll like pre spool to keep it responsive. But once the turbo starts to spool your in cylinder density increases quickly reducing the required timing as the flame front starts moving quicker. hence flattening of the timing. If you are higher in elevation it will want more as well, I typically see in the spool zone 0ft or sea level map will be 0-3* 5500ft will be at say 3-6* and my 10k will be at 6-8*. But it easier to tune all maps the same where you are at first to get your map shape and timing right, then adjust your altitude maps based off your current map and your elevation.

[RGHTBrainDesign]

So after quite a bit of updates across the board, I landed on what I think is the ideal tune setup for my truck.

"Josh's" Curve that I adapted to work was pretty good, but the one that I produced earlier with a more rounded cruise section and linear timing curve in regards to fuel flow ends up driving better, having more response, and significantly better in tow regions.

Here is a detuned version of that tune for break-in:



What the truck is on now is enough to make me question the 650hp transmission build... It moves out with fury and haste. I didn't think roasting grippy Continental dually tires would be effortless like this.

The short of it is that I managed 26000psi and 200uS more vs. the detuned tow tune (in video), and it's incredible.

My last step now are tightening up the torque converter to stay locked more often (it can handle the torque).

Beyond impressed with this setup and the cleanliness of the tune/mapping/drivability.

[RGHTBrainDesign]

Reworking some TCC settings in HPTuners and Transmission (fluid level) things tomorrow, but she's a baaaad girl!

[DTMCreations]

Very inspired, thank you for your knowledge and detail. I?m learning a lot from all of you here.

[RGHTBrainDesign]

Very inspired, thank you for your knowledge and detail. I?m learning a lot from all of you here.

If you have anything specific you want me to go over, you're welcome to email me at [email protected]

[RGHTBrainDesign]

Fixed the shifting, limiter bounce, and bumped up fuel economy just a hair. I think we'll leave it there. Truck is beyond happy now.

Gentle Haze + Higher Commanded Transmission line pressures = really happy truck.

Happy Easter everyone!

[RGHTBrainDesign]

Put together a new timing curve on a whim and it's brilliant now.

That was the last piece of the puzzle, I think.

Now it's time to reshape for altitude on each timing table (simple degree change per step or something along those lines), final pedal mapping, and confirm we aren't dropping rail pressure on top-end with the 100GPH FASS setup. We have to be close to the edge of that 600hp range from the feel of this thing.

[JaegerWrenching]

Put together a new timing curve on a whim and it's brilliant now.

That was the last piece of the puzzle, I think.

Now it's time to reshape for altitude on each timing table (simple degree change per step or something along those lines), final pedal mapping, and confirm we aren't dropping rail pressure on top-end with the 100GPH FASS setup. We have to be close to the edge of that 600hp range from the feel of this thing.

I watched your video and that turbo combination lights very well! The truck moves out! Modern turbo tech is game changing, especially borg EFR and Garrett G series stuff. I'm curious where it lands timing wise as it spools very quickly. I tend to start low and work my way up to not overshoot. But typically I have to increase timing as most customers have larger lazier turbos, which don't want to light as fast. But no two trucks are exactly the same either. They all like a little more or less depending on the injector setup and their response time /rate shape. It's why I like to use the same injectors for all the trucks I can. I would bet your truck makes 600 around 2200us on 50%, I have a customer with 64VGT, DDP 150s, 07 5.9 stock LB with a hurt cylinder #3 and it made 613whp @ 1900us. Probably more left on the table but he tows with it and his goal was 600.

[RGHTBrainDesign]

I watched your video and that turbo combination lights very well! The truck moves out! Modern turbo tech is game changing, especially borg EFR and Garrett G series stuff. I'm curious where it lands timing wise as it spools very quickly. I tend to start low and work my way up to not overshoot. But typically I have to increase timing as most customers have larger lazier turbos, which don't want to light as fast. But no two trucks are exactly the same either. They all like a little more or less depending on the injector setup and their response time /rate shape. It's why I like to use the same injectors for all the trucks I can. I would bet your truck makes 600 around 2200us on 50%, I have a customer with 64VGT, DDP 150s, 07 5.9 stock LB with a hurt cylinder #3 and it made 613whp @ 1900us. Probably more left on the table but he tows with it and his goal was 600.

What's crazy is that this was that previous "gas tuner" mapping that I did prior to where the truck is now, and I have legitimately picked up at least 60HP over where that was with where I finalized things for towing. Your advice was rock solid about being more parabolic and exponential vs. linear. That really allowed me to get under the turbo even faster and allow for more fueling cleaner. It's disgustingly quick; even at 50% throttle now.

Not bad for little DDP 15% Injectors, huh?