High Output (AISIN) vs Standard (68rfe)

[mbarber84]

As someone who is researching what I want to order on a 3500, I read through this whole thread. I'm going with 3500 because I don't ever want to run out of payload again, and I test drove one with air suspension and I honestly don't know what the internet complaints are about unloaded stiff driving (maybe that's for non air suspension brands?). I absolutely could use one as my daily driver (this is NOT just a tow vehicle). So a 3500 over a 2500 it is!

Now the question for me is SO vs HO. For size reasons, I am limited to the tiniest HD truck I can get - a Ram crew cab short bed. My current brand new trailer is 34' and 8200#, with a mere 1050# tongue. I will never have to worry about payload again! Given that a 2500 with SO would have been completely fine for me pull/stop wise, the 3500 with SO would check all my same boxes. It *seems* like the HO is overkill for me when really all I want is a 2500 with 3k payload. It might be cool to have the HO to say "I don't even feel a trailer behind me!" but not really necessary (I think?).

Since I am limited to a 31gal tank, MPG is one thing I'm very interested in. From this thread, it looks like (unloaded) MPG in the SO will be roughly 3MPG better, at least hwy driving. That could mean 90 miles more on a tank, not bad! Now how about towing difference? I am used to ~10MPG in my F150 Powerboost with a 30gal so anymore more is a huge bonus. My rough guesses are ~12MPG with a SO towing and maybe ~13MPG with a HO or are they about the same once loaded up? Any experience in this area is welcome! According to user data from Fuelly, average fillups are ~2-3MPG better from 2500->3500 6.7L Diesel. BUT - the 3500 data doesn't distinguish HO vs SO even though HO is the majority, and neither of them distinguish towing fillups vs non-towing fillups.

View attachment 69042 View attachment 69043

Lastly, I'm concerned my wife may get excited about "upgrading" to a 5er in the future due to the truck capability (dammit, there goes my truck bed!). I cannot imagine us needing a huge destination trailer, but perhaps something in the 10-13k range, with pin weight <2500#. Is the SO still capable and ok with this? (forget the short bed 5er argument for a sec, I'm curious about the engine) According to the specs, the HO would only "buy" you ~4000# of "capability" in a crew cab shorty but I'm more interested in if the SO experience will be miserable or not a problem.

NOTE: The towing capability by VIN link worked 2 weeks ago and now doesn't. At the time I was looking up VINs of Limited/Longhorn CCSB's and saw payloads >3k which was really all I was looking at at the time. I wanted to again check a few SO vs HO units by scanning the nationwide inventory to look at the true GCVWR's and the damn tool is dead

Aside from the increase in HP / Torque, the primary advantage of the HO is that it automatically comes mated to the Aisin transmission, which is absolutely superior to the 68RFE. There’s a substantial increase in towing capacity when you opt for the HO / aisin combo. You’re buying a medium duty diesel. It needs to be mated to a medium duty transmission. The 68’s are marginal to start with, and leave much to be desired in terms of capacity and capability. Their track record is also far from stellar. (And it isn’t only due to trucks that are modified)

If the HO / Aisin is within your reach financially, I would highly recommend it.

 

[Brutal_HO]

MPG differences between SO/HO are IMHO, marginal.

Hook a trailer and these trucks get 10MPG give or take 1MPG.

Don't regret buying the HO/Aisin for a second.

 

[mbarber84]

MPG differences between SO/HO are IMHO, marginal.

Hook a trailer and these trucks get 10MPG give or take 1MPG.

Don't regret buying the HO/Aisin for a second.

Absolutely.

The transmission’s track record alone warrants the purchase. Aside from a select small group of 2022’s with the K1 snap ring issue, that transmission has been utterly unbeatable. It’s not hard to find hotshot trucks with 500-700K on them, all original drivetrain. Thats pretty impressive for a truck that’s towing at, or very near, its maximum weight rating pretty much 24/7.

 

[jkempken]

I have the SO and have a mild tune from Calibrated power, never really found that I needed more power.

If you are worried about range on your truck you can always replace the 31 Gallon tank with a S&B or Titan 52 Gallon tank. I put a Titan 50 gallon in my Megacab and absolutely love the range I get towing and Daily driving it. It is really nice being able to go 350-400 miles on a tank pulling a trailer. The biggest impact to your towing MPG is speed in these trucks. Keep it around 70MPH and you will get 10 plus MPG. Me and my buddies like to keep it at 80 plus and averaged 8.3 MPG this year on our trip from Wisconsin to Montana and back.

 

[thecastle]

As someone who is researching what I want to order on a 3500, I read through this whole thread. I'm going with 3500 because I don't ever want to run out of payload again, and I test drove one with air suspension and I honestly don't know what the internet complaints are about unloaded stiff driving (maybe that's for non air suspension brands?). I absolutely could use one as my daily driver (this is NOT just a tow vehicle). So a 3500 over a 2500 it is!

Having never driven a 3500 with rear air I can't comment, other than to say yes it likely rides much better for a lot of technical reasons plus you will always tow nearly level (big bonus). How well a 3500 rides depends a lot on the roads you drive, tire size/inflation, personal preferences. If you fine with it go for it!

Now the question for me is SO vs HO. For size reasons, I am limited to the tiniest HD truck I can get - a Ram crew cab short bed.

Since I am limited to a 31gal tank, MPG is one thing I'm very interested in. From this thread, it looks like (unloaded) MPG in the SO will be roughly 3MPG better, at least hwy driving. That could mean 90 miles more on a tank, not bad! Now how about towing difference? I am used to ~10MPG in my F150 Powerboost with a 30gal so anymore more is a huge bonus. My rough guesses are ~12MPG with a SO towing and maybe ~13MPG with a HO or are they about the same once loaded up? Any experience in this area is welcome! According to user data from Fuelly, average fillups are ~2-3MPG better from 2500->3500 6.7L Diesel. BUT - the 3500 data doesn't distinguish HO vs SO even though HO is the majority, and neither of them distinguish towing fillups vs non-towing fillups.

To me the main reason I went with a HO was for the AISIN transmission, as I spend a lot of time towing. I will mention maintenance is more expensive with 30K oil tans oil changes and 60K oil/filter changes

I'm echoing others, the superior reputation of durability of that transmission over the Chrysler trans was the reason I only considered an HO.

As others have already pointed out a large proportion of 3500's are dually's and are probably spending a lot more time towing. Most hot shot'rs are going to be driving a 3500, so are most 5th wheel owners. I suspect a lot more 2500 owners from observation use them mostly as car replacements (they do around here). I upgraded my fuel tank to a titan 50+ gallon tank and couldn't be happier, to improve range while towing and unloaded. I've not ever seen an apples/to/apples comparison same day, same route, like TFL does between a 3500 SO/HO (it would be great to fin one). My suspicion if all else is equal, driving technique that the HO due to its lower compression ratio is slightly less fuel efficient. But because of the enhanced hp its able to hold higher gears for longer than the SO, under loaded conditions which could improve economy and can probably run a taller rear diff carrying the same load.

Lastly, I'm concerned my wife may get excited about "upgrading" to a 5er in the future due to the truck capability (dammit, there goes my truck bed!). I cannot imagine us needing a huge destination trailer, but perhaps something in the 10-13k range, with pin weight <2500#. Is the SO still capable and ok with this? (forget the short bed 5er argument for a sec, I'm curious about the engine) According to the specs, the HO would only "buy" you ~4000# of "capability" in a crew cab shorty but I'm more interested in if the SO experience will be miserable or not a problem.

I'd reconsider the short bed. A long bed is a better choice if your going to tow a 5th wheel. You're much more likely to have the clearance to properly center the hitch (fore/aft) and less likely to have issues with hitting the cab in tight turns. Most people end up with long bed duallys for towing a 5th wheel for clearance and enhanced stability of the wider stance.

The SO will be fine, people towed with a lot less power. I think people focus too much on power and don't consider as much the other important aspects of towing, like high wind stability, range, braking, ease of seeing out to hitch, sag/sway... I tow my trailers with a 7.3L powerstroke dully which had 230hp when new (350K miles ago). Its slow as hell, drinks fuel (6mpg), but it gets the job done. I think the difference between 370hp vs 420hp won't be huge, when you're looking at the power to weight ratio of the overall setup.

 

[loveracing1988]

I have the SO and have a mild tune from Calibrated power, never really found that I needed more power.

If you are worried about range on your truck you can always replace the 31 Gallon tank with a S&B or Titan 52 Gallon tank. I put a Titan 50 gallon in my Megacab and absolutely love the range I get towing and Daily driving it. It is really nice being able to go 350-400 miles on a tank pulling a trailer. The biggest impact to your towing MPG is speed in these trucks. Keep it around 70MPH and you will get 10 plus MPG. Me and my buddies like to keep it at 80 plus and averaged 8.3 MPG this year on our trip from Wisconsin to Montana and back.

I have a 2020 HO and towing my fifth wheel from 65 mph to 75 mph I get the same exact fuel economy. It is always an average of 10 on a trip once I average all tanks together.

 

[jetlag]

I have a '21 3500 Laramie, long bed, SRW, 50-gal fuel tank and the SO engine. and air suspension. I am getting 10-11 mpg pulling at my self imposed limit of 65 mph towing a 16K fifth wheel. If not pulling, we live in a semi-rural area, I get 19-20 mpg or better if I keep my foot off the gas. The long bed makes the clearance issues with fifth wheels a non-event. The truck pulls fine, plenty of power. I can count on 500+ miles pulling the camper before I need a fuel stop. That is around 150 miles more than I am willing to drive in a day. I have the oil/filter and fuel filters changed every 10K miles, not cheap unless you do it yourself. The ride is wonderful when loaded, and "stiff" when empty. That would improve if I let air out of the tires that sit at 80psi. I am too lazy to play the deflate/inflate game.