Cummings with 3.42 axle ratio be enough?

[Yukonbill]

I am looking to upgrade my 06 Megacab 1500 with a 5.7 Hemi to a 2013 2500 with a Cummins Turbo with 10,000 miles on it.. I am pulling my 2015 Keystone Laredo 291TG that is 33' in length and has a gvwr of 8200lbs.. The 2013 2500 has 3.42 axle ratio a payload of 2300lbs and towing capacity of 17,200lbs.. Will the 3.42 ratio have plenty of power for the vast hills we have here southwestern Pa? Or should I be looking for one that has 3.73's in it?

I’m selling my Ram 2500 with turbo Cummins , 3.42 axle, top condition.

 

[WY-Dave]

I have a '18 2500 CTD with the 3.42s. I have towed our 29' 7800# camper on 5% and 7% grades with no issues. It is also my DD with 18 each way avg 16.4-17.1.

With the Mullen fire, we evacuated my bro-in-laws ranch and I towed his 32' 11k (loaded with evac stuff) camper on the 7% grade part and no engine/trans heat problem

I had the same choice when Iwent looking
6.4-liter V-8 rated at 410 hp and 429 lb-ft of torque.
12160 67% of rating (8200#)

6.7-liter Cummins turbodiesel I-6 engine is rated at 370 hp and 800 lb-ft of torque.
17120 48% of rating (8200#)

it's like which has the easier time a regular plow horse or a Clydesdale.

It is also my DD with 18 each way avg 16.4-17.1. On the cold days <32, i turn on the block heater 2 hrs before leaving for work and less than 5 miles it's at normal temps

 

[SouthTexan]

I had the same choice when Iwent looking
6.4-liter V-8 rated at 410 hp and 429 lb-ft of torque. 17120 48% of rating (8200#)
6.7-liter Cummins turbodiesel I-6 engine is rated at 370 hp and 800 lb-ft of torque. 12160 67% of rating
it's like which has the easier time a regular plow horse or a Clydesdale.

I think you got those numbers flipped. The tow rating on the Cummins is over 17k.

Also, it is best to tow the 3.42 geared Cummins trucks in 5th gear at speeds below 73 mph for the best efficiency. As you can see in the brake specific fuel consumption (BSFC) map below, the "sweet spot" for the Cummins is between 1,550 and 1,900 rpm so it is best to adjust gears to be within this rpm range when towing. Sixth gear will generally put you well bellow this "sweet spot" when towing between 60-70 mph.

 

[johnspd]

I am looking to upgrade my 06 Megacab 1500 with a 5.7 Hemi to a 2013 2500 with a Cummins Turbo with 10,000 miles on it.. I am pulling my 2015 Keystone Laredo 291TG that is 33' in length and has a gvwr of 8200lbs.. The 2013 2500 has 3.42 axle ratio a payload of 2300lbs and towing capacity of 17,200lbs.. Will the 3.42 ratio have plenty of power for the vast hills we have here southwestern Pa? Or should I be looking for one that has 3.73's in it?

The 3.42 will be fine. Mine has a 3.73 and I wish it had the 3.42 to get the fuel mileage up and the RPM's down at highway speeds.

 

[SouthTexan]

The 3.42 will be fine. Mine has a 3.73 and I wish it had the 3.42 to get the fuel mileage up and the RPM's down at highway speeds.

Well the good news for you is that due to the changes Cummins made to the 2019+ standard output engines like increasing compression ratio and such, your "sweet spot" is much bigger. However, if you have the high output Cummins with the lower compression ratio, than your "sweet spot" probably did not change much and may even be smaller than the 2018.

The 2018 6.7L is on the left and the 2019+ 6.7L is on the right. As you can see, the 2019+ has a much larger "sweet spot" encompassing more rpms when towing. Unloaded, however, you will be burning slightly more fuel than the 3.42 since you will be below 100 Nm and less rpms are better for fuel economy there.

 

[WY-Dave]

I think you got those numbers flipped. The tow rating on the Cummins is over 17k.

Also, it is best to tow the 3.42 geared Cummins trucks in 5th gear at speeds below 73 mph for the best efficiency. As you can see in the brake specific fuel consumption (BSFC) map below, the "sweet spot" for the Cummins is between 1,550 and 1,900 rpm so it is best to adjust gears to be within this rpm range when towing. Sixth gear will generally put you well bellow this "sweet spot" when towing between 60-70 mph.

Site your right teach me to post late at night Thanks again fixed

 

[tjfdesmo]

Well the good news for you is that due to the changes Cummins made to the 2019+ standard output engines like increasing compression ratio and such, your "sweet spot" is much bigger. However, if you have the high output Cummins with the lower compression ratio, than your "sweet spot" probably did not change much and may even be smaller than the 2018.

The 2018 6.7L is on the left and the 2019+ 6.7L is on the right. As you can see, the 2019+ has a much larger "sweet spot" encompassing more rpms when towing. Unloaded, however, you will be burning slightly more fuel than the 3.42 since you will be below 100 Nm and less rpms are better for fuel economy there.

Great info ST! And confirms what I felt with my '19 HO. Hard to find the sweet spot. Have you got the graph for the HO?

 

[SouthTexan]

Great info ST! And confirms what I felt with my '19 HO. Hard to find the sweet spot. Have you got the graph for the HO?

Not at the moment, but I can reach out to some of my old collogues at Cummins. The HO should be very similar to the 2018 engine, but just a little smaller area of dark blue.

 

[SouthTexan]

@tjfdesmo I will add that even 200 g/kw-hr in the slightly lighter blue section is really good in comparison to the Duramax and Powerstroke. The last BSFC map I seen of the 6.7L Powerstroke showed that it's sweet spot was at 205 g/kw-hr and increases consumption from there while the sweet spot on the Cummins starts at 190 g/kw-hr.

 

[Gr8bawana]

I tow my 25' TT which max's out at maybe 8500lbs with my 2017 CTD with zero problems. I set the CC at 65mph, lock out 6th gear and enjoy the drive. This let's the engine hum along at a paltry 1900rpm. I have yet to climb a mountain highway that causes the trans to downshift. The steepest to date is 7% and it held 65mph with no problem.
The towing power of these trucks is incredible.

 

[JayLuke]

My tows fine with 3.42's but it wants to do 70 mph in 6th which is not a good thing in the 55 MPH areas. Also I want to go to 35" tires and I think it will be too tall to use 6th gear much at all towing.

 

[2018 Hemi]

Stay with the 6.7 but don’t settle for anything lower than a 373 gear. Had to diesels 5.9 and 6.7 with 410’s, now I have the 6.4 with 373 gears and not happy. No we’re near the power when needed.

 

[ExpVet1]

i have the 15 3500 with 3.42 and tow a 12k toy hauler. no issues. however i found that my city mileage is trash. Its 12-13 average hand calculated.