Diesel - Will i regret regearing to 4.88?

[cotnballs2000]

4.10’s aren’t worth the effort. You’re gonna be 200ish rpms lower than stock with 4.10’s and 37’s vs 3.73‘s and 31’s. Borderline lugging the motor. Efficiency will go down I’m betting. Minimum 4.56‘s for 37’s, 4.88’s are better…

You are wrong on the RPM, see the chart. Changing gears is to get you back into the working RPM range of the engine. We do not drive 3.6L with max torque 4,400 RPM. Max power of the diesel is 1,400 RPM (Diesel has 182 ft lbs of torque more than the 3.6) and we have a turbo diesel that loves load. Lots of people are running stock 3.73 with 37s without any issues.

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[rharr]

You are wrong on the RPM, see the chart. Changing gears is to get you back into the working RPM range of the engine. We do not drive 3.6L with max torque 4,400 RPM. Max power of the diesel is 1,400 RPM (Diesel has 182 ft lbs of torque more than the 3.6) and we have a turbo diesel that loves load.

Max torque is roughly between 2000 and 2600. 1600- 1800 is where it starts to wake up.
Am I missing something?

 

[cotnballs2000]

Max torque is roughly between 2000 and 2600. 1600- 1800 is where it starts to wake up.
Am I missing something?

Jeep list max torque at 1400 RPM, this is a wheel dyno with unknown tune, gear and tire size.

Jeep Gladiator 3.0L EcoDiesel Specs

Jeep Gladiator 3.0L EcoDiesel Years	2021+
Engine Configuration	60-Degree Diesel V-6
Block Material	Compacted Graphite Iron
Cylinder Head Material	Aluminum Alloy
Displacement	182 Cubic Inches
Bore	3.27 inches or 83 cm
Stroke	3.60 inches or 92 cm
Compression Ratio	16.0:1
Firing Order	1-2-3-4-5-6
Fuel Injection	Common Rail Direct Fuel Injection, 29,000 psi (2,000 bar) Solenoid Injectors
Turbocharger	Water-Cooled VGT Variable Geometry Turbocharger
Valvetrain	Chain-Driven DOHC (Dual Overhead Camshafts), 24 Valves, Hydraulic lash adjusters with roller finger followers
Transmission	TorqueFlite 8HP75 8-Speed Automatic /w Overdrive
Oil Capacity	9.0 Quarts (8.5 Liters)
Coolant Capacity	12.3 Quarts (11.8 Liters)
Fuel	Ultra-Low Sulfur Diesel
Fuel Tank Capacity	18.3 Gallons
DEF Tank Capacity	5.1 Gallons
Horsepower	260 horsepower @ 3,600 rpm
Torque	442 lb-ft of torque @ 1,400 rpm
Max Engine Speed	4,600 rpm
Fuel Economy (MAX)	22 City – 28 Highway – 24 Combined
Emissions Systems	Dual-Loop Exhaust Gas Recirculation System, SCR /w UREA Injection, Diesel Oxidation Catalyst, Diesel Particulate Filter

 

[rharr]

Ok i will grant you that. But wouldn't this chart still be of value to give you a real world outcome? I can tell my ecoD pulls harder once it gets a little more rpm.

Also the more rpm the more boost, more boost more power, the chart below would seem to represent that also.

One can also infer that the dyno chart below is using stock wheels and gears what ever they may be, because GDE has stated they will not offer a tune that accounts for bigger tires or different gears.

So that being said the chart above is a good representation of a stock setup and what would be experienced in the real world?

I rather tune with real world data then some blanket statement jeep puts out with out any support evidence.

Hell if you want to anal about things google all the ecoD dyno pulls you can find, and plot a average of the power curve then use that for your tune. But i suspect it won't move by much.

This being a re-gear discussion, wouldn't wheel dyno power curve be what we want to know?

Jeep list max torque at 1400 RPM, this is a wheel dyno with unknown tune, gear and tire size.

 

[cotnballs2000]

Ok i will grant you that. But wouldn't this chart still be of value to give you a real world outcome? I can tell my ecoD pulls harder once it gets a little more rpm.

Also the more rpm the more boost, more boost more power, the chart below would seem to represent that also.

One can also infer that the dyno chart below is using stock wheels and gears what ever they may be, because GDE has stated they will not offer a tune that accounts for bigger tires or different gears.

So that being said the chart above is a good representation of a stock setup and what would be experienced in the real world?

I rather tune with real world data then some blanket statement jeep puts out with out any support evidence.

Hell if you want to anal about things google all the ecoD dyno pulls you can find, and plot a average of the power curve then use that for your tune. But i suspect it won't move by much.

Dyno numbers DO NOT represent the real world because they are done full open throttle in the transmission gear closets to 1:1 ratio, so 7th gear. The whole run you are looking at is a one gear run, and thats why you are seeing those RPM and toqure number. I googled and looked at a few EcoDiesel wheeled dyno number and all the OEM ones were different because all dynos are different, even the exact same model can spit out different numbers. I dragged raced a turbo car for a decade and been on a bunch of dynos, I know how they work.

 

[rharr]

Yes as I have to, and the general rule of thumb I have followed is to try and match stock rpm/speed charts when doing a regear tire size bump. Generally speaking the manufacturer has done a OK job at selecting a stock combination of tires and gears to match engine output to cover the broadest range of use, this is good for a passenger vehicle.

If you have specific needs then move outside of the manufacturers ratios and tune for what you need. I don't need my motor spinning 800 rpms faster at 70 mph so I don't plan on getting extra tall gears that don't match stock rpm/speed ratios.

We are both debating minutiae as the ecoD has such a early torque curve and pretty high rpm range that it is very forgiving of a sloppy re-regearing.

We are not building a race car where we are trying to match a power output to planned operation range.

 

[Vtur]

Isn't factory max torque rating is at the crank? The wheel torque curve gonna be at a higher rpm, the graph shown that.

I don't have a lot of knowledge regards to diesel as this is mine first, but have experience with turbocharged small 4 bangers, down to the Honda Cub 90cc engine, that i was able to get it up to 66mph by modifying the motor plus a regeared sprockets. Don't laugh lol.

 

[M390]

You are wrong on the RPM, see the chart. Changing gears is to get you back into the working RPM range of the engine. We do not drive 3.6L with max torque 4,400 RPM. Max power of the diesel is 1,400 RPM (Diesel has 182 ft lbs of torque more than the 3.6) and we have a turbo diesel that loves load. Lots of people are running stock 3.73 with 37s without any issues.

All I know is after switching to 35‘s which actually measure closer to 33.5” tall my Gladiator drops into 7th pulling slight grades and bucking head winds very regularly. My Jeep gets driven a 300 mile trek pretty often so that’s not a fluke. On stock sized 31’s (actually closer to 29.5-30”) it didn’t do that.
Add a 5000 lb camper and that effect is hugely compounded. For my purposes I’m gonna try 4.56’s. Would consider 4.30’s as they’d put one back closest to stock configuration rpm’s but I can’t find them anywhere currently. I don‘t mind tryin a little extra leverage for towing and I highy doubt the extra 145 rpm is gonna hurt a thing. My mileage dropped 8-9 mpgs switching from 31’s to 35’s, 3.73’s being the same. Some of that is absolutely a loss of aerodynamics, extra rotating mass/resistance, contact patch, etc. I suspect some of it is also from lugging the motor…

 

[Jocww]

I made a deal to get some yukon 4.88 gears locally. my Sport has 3.73 gears and its not so bad, but since im installing ARB lockers i figured id regear. i just conflicted if i will lose too much mileage since i normally drive at 75. thoughts? 37" patagonias with a 3.5 metalcloak gamechanger. thanks.

In a word... Probably...or Absolutely. Your choice on verbage

 

[HVYMETL]

I have 4.88s with 35s... little high rpms on the highway but once I go to 38s, it will be great again. Driving in the mountains has plenty of power to stay in 8th or 7th when passing.
4.88s w/ 35s on the street is like a race car and still get 23.5mpg.

Merging on a highway is awesome, I usually have to slow down a bit. You're never regretting having that acceleration. I do also have the Banks Pedal Monster

 

[Ericshere03]

I have 4.88s with 35s... little high rpms on the highway but once I go to 38s, it will be great again. Driving in the mountains has plenty of power to stay in 8th or 7th when passing.
4.88s w/ 35s on the street is like a race car and still get 23.5mpg.

Merging on a highway is awesome, I usually have to slow down a bit. You're never regretting having that acceleration. I do also have the Banks Pedal Monster

That’s the most aggressive I’ve heard anyone doing. I am thinking the same, I have 35’s and tow a trailer, HOWEVER, I know I’ll be on 37’s eventually, if the gearing sucks, I’ll move even sooner .

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