2025 Laramie with Twin Turbo 6 engine tune, Cat6 or JBL4???

[Laramieblue]

I am not a high speed junkie but retired and like to get better mileage on highway that is greater than my 17 mpg. When I tow a 5,000lb travel trailer I usually get 8-9 mpg going around 60-65 mph on highway with cruise control on.
Has anybody installed an engine tune package that has increased their low rpm torque and hopefully mpg as well?
I am hoping that having an increase in low rpm torque will lower my cruising rpm and thus increase my mpg.

 

[Laramieblue]

Here is the response to my email to the JBL4 folks:
We don't have any dyno data using 89 octane, you need to use 91+ or better with the Jb4 installed & turned on. The JB4 does not alter or change the OEM TCU / transmission mapping, that will stay the same. Generally speaking under normal driving scenarios expect MPG to say similar / the same. Under WOT / heavy acceleration periods MPG tends to decrease with the added HP / TQ demands.

It seems like the only option for utilizing the JBL4 tune is to run 91 octane, for a 33 gallon gas tank that will increase the cost to fill up by around $18 and still no guarantee I get enough mileage to cover the cost of the higher fuel cost.

 

[CalvinC]

No tune will improve mpgs despite the marketing hype. Your most economical tune is the factory tune combined with a deliberate right foot.

If tweaking a few lines of code would have netted more mpg you can be sure the OWM would have done it to earn more Greta points.

Tunes on modern engines get more power by adding timing and boost.

More timing requires higher octane fuel, which is why they don’t bother with lower octane fuels.

More boost requires more fuel to suit, less you run lean, which is why no tune that adds power would also improve mpgs.


All that said, tunes are fantastic for many other priorities, and I would not hesitate to use a Jb4 if I owned a Hurricane (though I’d drop it for true custom tuning if/when that becomes a possibility).

 

[Laramieblue]

When I had my 2016 Tacoma with V6 engine and towing my 5100 lb. travel trailer going down I5 south of Portland, Oregon. My engine would constantly shift down to get back to speed then shift up once I reached my set speed while on cruise control. This would constantly repeat itself while on flat ground. I installed a Tune that raised my torque at lower RPMs (around 2500) which helped to prevent this gear hunting exercise. Since the tune allowed me to drive 62 MPH while keeping my RPM within the 2500-2600 range I got 1-2 more MPG.

I was hoping to get the same results with my Ram.

My theory is that by increasing the torque at lower RPMs ranges my RPM would be lowered to maintain the same speed. I am hoping also that the transmission is in one of the upper gears to maintain speed with lower engine RPM. Lower RPMs means less gas required to run engine as well as all the emission monitoring sensors and computers allow the tune to work. I am a retired engineer so I have a basic understanding of the science behind combustion engines but with all the new computers trying to maintain emissions standards it is hard to know how they impact timing and fuel settings.

From what CalvinC is saying it sounds like the tune will forward the timing more than factory settings to get a longer and more complete gas burn; thus increasing torque. That would also explain the need for higher octane fuel which helps to reduce pinging at advanced timing settings as well as improving on a complete gas burn within each ignition cycle.

Does anybody out there with more technical expertise (than I) on the science of engines, can contribute to the understanding on the feasibility of a tune giving me better mileage while towing at lower RPMs. I have attached 2 pictures showing my RPM with given speed and MPG.

 

[koren388]

Most tunes on the 6TT are aimed more at power than mpg, but you can get a little bump in low-end torque. I know a couple guys running mild tunes who said they picked up maybe 1–2 mpg when cruising empty, but towing numbers didn’t change much. A good intake/exhaust setup plus staying on top of tire pressure usually makes just as much difference as a tune

 

[CalvinC]

Lower RPMs means less gas burned by the engine…

… Is a true statement for naturally aspirated engines.

With turbocharging it goes out the window a bit unfortunately for a few reasons.

ECM strategy will call for a rich fuel trim under high load / low rpm scenarios for a couple reasons. Without RPM the big power maker is boost, and as boost increases so does heat, and enriching fuel delivery combats this.

Only at higher RPMs can we lean on timing for material power adding.

Where small turbo engines show their MPG superiority is only at low load / low RPM scenarios. This is why they look better in EPA tests but get worse mpg towing than the old V8s.