Kindly help me choose between Standard and High Output Cummins

[hdas]

I'm documenting my buying process here. But this is a specific drivetrain question which is very appropriate in this esteemed forum. This is my use case:

1. Overlanding Vehicle. Living at 8000ft of elevation. Heavy Winter.
2. Lots of offroad climbing (and descending) in treacherous mountain passes in Colorado.
3. Not a daily driver. Will be use for short trips in the weekends and longer trips (3-6h each way + roaming in the trip) likely once a month.
4. Calculated payload needed including bumpers, roof racks, rock sliders around 2500lbs.

I have decided for a Diesel, so there's no point in talking about the Hemi. But I want to be able to objectively decide about standard vs high output. Saving $3k is fine, but money is no object. Here's the main criteria I'm considering, in equal weightings:

1. Fuel economy
2. Reliability and Longevity
3. Performance for my use case

It's hard to find comparisons, specially long term. I appreciate if you guys have any insights, first hand experience, links to other resources, and everything else you think can help me make an objective decision.

Thanks a lot.

 

[H3LZSN1P3R]

Standard output would be more than enough for you as would the hemi. The HO would be ideal for the trans though

 

[hdas]

The HO would be ideal for the trans though

Would you say that the improvement in the ASIN transmission is more than enough to compensate for any other shortcoming of the HO engine?. Kindly elaborate.

 

[H3LZSN1P3R]

Would you say that the improvement in the ASIN transmission is more than enough to compensate for any other shortcoming of the HO engine?. Kindly elaborate.

Not really the way the aisin shifts is not to ideal for offroad conditions its just a stronger trans. The 68RFE is great especially with trans tune

 

[CdnHO]

Would you say that the improvement in the ASIN transmission is more than enough to compensate for any other shortcoming of the HO engine?. Kindly elaborate.

I haven't found any shortcomings in my HO. Let's face it, you don't buy these things for fuel economy. I get around 15 running around and 9.7 towing 22K fifth wheel. Calculated. I do drive conservatively.

 

[tchur1]

1. Fuel economy
2. Reliability and Longevity
3. Performance for my use case

1) this is going to be highly variable based on how one drives and there doesn't seem to be conclusive evidence IMO that the SO performs markedly better than the HO for fuel economy. See this thread:

High Output (AISIN) vs Standard (68rfe)

Anybody who has driven both from the 2019-2020 models, did you notice a difference? Did the H.O. seems louder? Did the H.O. seem more gruff? They felt different in the shifting, one didn't seem faster than the other. The sales manager told me that if I had a load on the high output one that I'd...

hdrams.com

I get about 19 MPG highway unloaded and 13 mpg when towing about 10k pounds.

2) AISIN is probably your best bet here, this is the reason I went HO vs SO when I ordered my truck. Outside of the snap ring issue on the 22's this trans has been close to bulletproof. I think it shifts quite well for a medium duty trans and have never wished I had the 68rfe.

It also seems the 68rfe has gotten a lot stronger in the 19+ trucks. You see far fewer issues in the current generation than in the older trucks. It likely is more than enough for your use case.

3) I think it depends on how you define "performance" but if money isnt an issue id just get the HO. You're already spending ~100k on a truck, get the MOST capable one. I also live at elevation (~6500 feet) and deal with mountain terrain like you outline.

 

[Ostracize]

I'd second (or third? lol) the HO aisin opinions, as it's built heftier for sure. As far as shifting, unladen is most definitely not as smooth as the 68 but from my experience once loaded with anything significant shifts quite nicely which I do believe I've read others on here have experienced. But ultimately dealer's choice.

 

[AH64ID]

The HO for the lower 1st and 2nd gears, as well as a more robust transmission.

I'm not aware of any HO shortcomings, but if you're making more power you will use more fuel.. but at least you have the power.

 

[gimmie11s]

Since "money is no object" the obvious choice for you is a 6.4 truck with twin turbos and a swapped in G56. Diesel for short trips is stupid and a waste of capability.

Get er done young gun.

 

[jebruns]

Not really the way the aisin shifts is not to ideal for offroad conditions its just a stronger trans. The 68RFE is great especially with trans tune

A great point. You say you are going to be on treacherous mountain passes in heavy winter. A tranny that shifts more abruptly, which the Aisin has a rep for, could get you in a lot of trouble. For you needs, if it were me, I'd go with the SO. Smoother shifting and better MPG would seem to better suit your use case.

 

[AH64ID]

A great point. You say you are going to be on treacherous mountain passes in heavy winter. A tranny that shifts more abruptly, which the Aisin has a rep for, could get you in a lot of trouble. For you needs, if it were me, I'd go with the SO. Smoother shifting and better MPG would seem to better suit your use case.

I can’t say that I’ve ever thought my Aisin shifted so abruptly that it was a detriment to driving in hazardous winter conditions. It’s not a harsh shift, but more of a firm shift. Nothing that’s going to cause you to lose traction on a shift, at least not any more than any transmission.

I do spend some time on slick winter roads and think the truck does great for its size and weight.

 

[H3LZSN1P3R]

A great point. You say you are going to be on treacherous mountain passes in heavy winter. A tranny that shifts more abruptly, which the Aisin has a rep for, could get you in a lot of trouble. For you needs, if it were me, I'd go with the SO. Smoother shifting and better MPG would seem to better suit your use case.

Not what i was meaning. I was more meaning the ratios i find that the SO has a better shift pattern for the off trail stuff. But its really personal preference nothing that is going to cause issues off road

 

[Riddick]

You mentioned payload but do you plan on towing with your new rig? Based on your payload alone you will be on a 3500 chassis, correct?

Assuming you do not plan on towing much I would recommend a 3500 with the SO. Sure, the HO makes more power but unloaded the SO will be more responsive, get better MPG, and is faster 0-60. The SO has a higher compression ratio which will make the truck feel more responsive and net overall better fuel economy. Hook up a trailer and the HO will dominate the SO in terms of performance, it all boils down to how you will use your truck.

The AISIN is by far the more reliable transmission but the 68RFE is not terrible. The AISIN will require more servicing (shorter maintenance intervals) but if you are focused on reliability alone the AISIN wins hands down. Although, the 68 has seen improvements over the years it still is not as reliable as the Aisin.

 

[hdas]

do you plan on towing with your new rig?

No towing planned. I'm building a capable 4x4 overlanding rig so I don't have to buy a smaller truck (Tundra) and tow a trailer. That's how much I dislike the idea of towing, for now.

Based on your payload alone you will be on a 3500 chassis, correct?

Correct

Thanks a lot for your poignant answer.

In your opinion, does the superior reliability of the AISIN transmission offset the responsiveness and better MPG of the SO engine?. In other words, you have mentioned two important points for and against the AISIN/HO combo, my question is, IN BALANCE, does the SO come on top, given my specific application?

 

[Brutal_HO]

The HO will hold the exhaust brake down to 900RPM/~12MPH in 2nd gear. I don't think the 68RFE goes below 1100RPM/15MPH (?)

Perhaps the 68RFE can be tuned to do similar but could possibly decrease the longevity on a stock trans.

The HO/AISIN has a bigger transfer case, BW44-48.

 

[AH64ID]

From what I understand the Aisin also runs cooler.

About the only benefit I see to the 68RFE is that it can be tuned, which still isn't easy/cheap on the 22+ trucks.

As for compression ratio and responsiveness, I'm going to say it's likely not noticeable. My 22 has lower compression and is more responsive than my 18 was. When I rebuilt my 05 it went down to 16.8:1 and improved response. Yes there are other variables, the point is that the compression ratio is likely not anything to sway a decision one way or the other.

Speaking of compression ratio, the higher compression ratio will likely burn more DEF and/or use more EGR as NOx is increased with higher cylinder pressure.

 

[Brutal_HO]

From what I understand the Aisin also runs cooler.

About the only benefit I see to the 68RFE is that it can be tuned, which still isn't easy/cheap on the 22+ trucks.

As for compression ratio and responsiveness, I'm going to say it's likely not noticeable. My 22 has lower compression and is more responsive than my 18 was. When I rebuilt my 05 it went down to 16.8:1 and improved response. Yes there are other variables, the point is that the compression ratio is likely not anything to sway a decision one way or the other.

Speaking of compression ratio, the higher compression ratio will likely burn more DEF and/or use more EGR as NOx is increased with higher cylinder pressure.

But wouldn't more boost also then use more fuel?

The HO also has a 12" R&P rear...

 

[AH64ID]

But wouldn't more boost also then use more fuel?

The HO also has a 12" R&P rear...

Yes, well more power generally means more fuel... but only when you're making it.

 

[Riddick]

In your opinion, does the superior reliability of the AISIN transmission offset the responsiveness and better MPG of the SO engine?. In other words, you have mentioned two important points for and against the AISIN/HO combo, my question is, IN BALANCE, does the SO come on top, given my specific application?

In my "opinion" I feel the SO is better suited for your application. My main reason for this based on the fact you will not be towing. However, my best advice is to go out and test drive both and see if you even notice a difference in how they drive.

Other forum members have said there is little to no difference in terms of responsiveness, its all subjective. I based my comments on a Youtube review video posted by JB Reviews in which he tested a SO vs. HO 0-60. The HO appeared to be laggy off the line compared to the SO. The lag could be in the trans tuning or it could be from the engines but to me there was a difference in responsiveness between the two.

.

 

[UglyViking]

I'm currently in the process of building out my 2019 2500 (SO obviously) for the purpose of being an overland/daily driver rig. I also have a 2015 3500 DRW HO with 4.10s that I use to tow my 44' toy hauler. Here are my thoughts/observations.

• It seems you're set on a 3500, so that is a great choice if so. The thing I'll say about the 2500 is that is has great articulation, and with the help of softer springs and airbags with cradles can support about 6k front and rear axle weight. That should be enough to carry everything you want, but you're def going to have trade offs. Everyone has thoughts on payload/axle ratings and all that, so I'm happy to deeper dive my thoughts if you're interested, but that's a choice you'll want to make.
• Since you're set on the Diesel (as am I) and money is no object, I'd strongly recommend the SO with the 68rfe. The 68 has seen improvements in key areas vs older versions, and if you buy a build 68 from a place like Randy's you're going to get a trans that is smoother shifting with a better gear ratio for what you want than the Aisin, in my opinion. (Obvious bias here, I bought the SO for this exact reason)
• The HO has a great transfer case and trans behind it, but that said it suffers on MPG (one of my driving factors for an overland vehicle) and shifts like a medium duty truck. I think the first gear in the Aisin trans would be good for crawling, but you had to deal with a bit of flare shifting, which isn't ideal for an off-road vehicle. Plus addition weight from the heavier components.
• The Aisin has no trans tuning available, meaning how it shifts from the factory is how it shifts forever. There has been discussion about the ability to tune the Aisin "coming soon" for probably the past decade, and yet no one has cracked the code. The 68 can be made to shift more towards what you want, and again if you buy a built trans, or add built components, you're going to beef up the 68 to a point that it's at least as strong as the stock Aisin.

You can do what you want with either trans, but I think the SO is the better move of the two, doubally so if you're willing to spend the additional coin on a built trans.

Also, for what it's worth, my 2019 almost fully loaded Laramie has 2200lbs payload (plus another 1-2k before it hits axle ratings). With your requirements I think you could go either 2500 or 3500 depending on how you feel about the rear suspension.

P.S. I saw your post about the Expo rear carrier on Expo. I recently purchased a front bumper from them, and I'll say that the product seems well enough built but there are some minor issues, and their shipping/CS is poor at best. I mean to write up an article about my experience and share it on the forum. I started to document my experience in this thread, and while it's finally "resolved", I'd say that my experience is far less than ideal.