High Output (AISIN) vs Standard (68rfe)

[RamGuy84]

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 notice the difference between the two. Thoughts on this?

 

[Bozo]

Probably correct on the loaded part, except it would just take longer for the downshifts as a result of the increased torque. As for seat of pants drag racing, no. Torque management is at play.

 

[RamGuy84]

To me it felt and sounded more muscular, if that makes sense.

 

[Bozo]

To me it felt and sounded more muscular, if that makes sense.

were they geared the same?

 

[RamGuy84]

Yes both 3.73

 

[Zeroday]

I tested both, and didn't notice that one was louder or much different feeling than the other - the bigger difference I noticed was between the air suspension and not. Unloaded they seemed fairly comparable.

 

[elephantrider]

it's the same engine, just marketing ploy

 

[Brutal_HO]

it's the same engine, just marketing ploy

How so?

Same block, probably the same head.

Different injectors, different compression ratios (many assuming pistons).

The HO also gets the 12" AAM rear and a bigger transfer case.

 

[thestuarts]

it's the same engine, just marketing ploy

Same block, probably the same head.
Different injectors, different compression ratios (many assuming different pistons).
The HO also gets the 12" AAM rear and a bigger transfer case.

Watch this video: Here's how the Cummins Diesel in the 2019 Ram HD Makes a Huge 1,000 Lb-Ft of Torque!
Here is a summary of what's stated in the video: [mod: the video is misleading, many of these statements attributing these improvements to ONLY the HO are false]

1. The HO block is made out of Compacted Graphite Iron (CGI) material which is stronger.
2. The crankshaft is strengthened.
3. Stronger main bearing caps with larger bolts.
4. The flywheel has 10 bolts for increased strength. The previous version had 8 bolts.
5. The flex plate is thicker and stronger.
6. The damper at the front of the engine has been retuned.
7. Increased the diameter of the piston pin and the bushings.
8. The cam is now a hollow billet cam.
9. They added a scissor gear to the front for Noise, Vibration and Harshness (NVH) control.
10. Hydraulic lash adjusters. This means there is no longer a requirement for overhead adjustment.
11. An "enhanced" turbo charger.
12. Bosh CP4.2 fuel pump to increase injection pressure. [This pump is controversial]
13. It is 60 lbs lighter
14. The maintenance interval on the breather filter has gone up to 75,000 miles.
15. The anticipated life of the engine is such that at 250,000 miles 10% of the engines will need a rebuild and at 350,000 miles 50% of the engines will need a rebuild.
16. A more efficient cooling system to handle the higher heat
17. Increased cylinder pressure

Watch this video: Rod Romain explains the differences in the HO. Here is a summary of what's stated in the video: [mod: the video is misleading, many of these statements attributing these improvements to ONLY the HO are false]

1. They increased the strength of the connection rods by going to a higher strength alloy.
2. They increased the strength of the crankshaft by going to a higher strength alloy.
3. They switched to a Compacted Graphite Iron (CGI) block.
4. New heads.
5. The turbo was improved for airflow (primarily on the compressor side).
6. The fuel pump is a new high pressure pump [Bosch CP4.2]
7. The injector lines were improved.
8. The engine water adapter and water outlet are both made out of aluminum instead of cast iron to save weight.
9. They went to a hydraulic lash adjuster. It is quieter, and it doesn't require a rocker adjustment at 100,000 miles.
10. Overall, the weight was reduced by 60 lbs.
11. They beefed up the Aisin transmission. The shift schedule was improved [this is controversial].
12. They beefed up the transfer case.
13. The front and rear drive shaft joints are larger, and they went to more of a CV-style joint with a slip-in spline. It is "more robust."
14. They reduced Noise, Vibration and Harshness (NVH) control with new dampers.
15. The exhaust hangers were redesigned.

Cummins' web site states states these improvements:

1. A Compacted Graphite Iron (CGI) material for the block allows us to increase the cylinder pressure capability while reducing the overall weight by almost 60 lbs
2. A new cast-iron cylinder head containing high-temperature capable exhaust valves actuated by all-new hydraulic lash adjusters in the block eliminates the need for valvetrain adjustment service intervals
3. The heart of the engine is a higher-strength alloy crankshaft with a 10-bolt crank flange driving newly-designed forged connecting rods and new bearings which transfer power from the low-friction ring-wrapped pistons
4. A new larger Cummins Holset variable-geometry turbocharger optimized with heavy duty bearings, and a new compressor-side housing is a key ingredient in the new ratings, pumping 33 pounds per square inch (psi) of fresh air into the engine
5. The new fuel-delivery system includes a new 29,000 psi (2,000 bar) fuel pump and fuel rail with Cummins Filtration “filter in filter” NanoNet® technology

As @brutal stated, the HO engine also comes with the 12" rear end (code AAM).

 

[Xflight29]

I would have to say that that's a new engine by Cummins.

 

[ST3500]

I had a 2016 with the 68rfe and now I have a 2019 with the Aisin.
Without going into a technical report, here is my honest opinion between the two transmissions driving both unloaded on a day to day basis.

The 68rfe is a smoother shifting transmission than the Aisin, The Aisin shifts gears quite firmly.
Driving downhill the Aisin will hold its current gear, the 68rfe will not do as well unless you're on tow mode.
The exhaust brake works a lot better with the Aisin, no matter which mode you're in.
The Aisin will occasionally fall into a false neutral on a stop and go situation.

Torque management is more noticeable with the 68rfe than the Aisin.
With the Aisin it feels like you're driving a commercial truck, the 68rfe is a more civilized tranny.

Both are good transmissions, you already know the difference in torque availability of both (and price difference)...……. ultimately, the choice is yours

 

[elephantrider]

my comment was in jest, folks lol

 

[Bozo]

my comment was in jest, folks lol

 

[Burn'n Oil]

...different compression ratios (many assuming pistons).

Has to be pistons - bore/stroke is the same for both engines but HO compression ration is substantially less than on the SO. HO gets extra grunt via the turbo. From the link provided by @thestuarts:

 

[MikeXM]

HO gets extra grunt via the turbo.

And more fuel apparently...

 

[Brutal_HO]

Watch this video: Here's how the Cummins Diesel in the 2019 Ram HD Makes a Huge 1,000 Lb-Ft of Torque! Here is a summary of what's stated in the video:

1. The HO block is made out of Compacted Graphite Iron (CGI) material which is stronger.
2. The crankshaft is strengthened.
3. Stronger main bearing caps with larger bolts.
4. The flywheel has 10 bolts for increased strength. The previous version had 8 bolts.
5. The flex plate is thicker and stronger.
6. The damper at the front of the engine has been retuned.
7. Increased the diameter of the piston pin and the bushings.
8. The cam is now a hollow billet cam.
9. They added a scissor gear to the front for Noise, Vibration and Harshness (NVH) control.
10. Hydraulic lash adjusters. This means there is no longer a requirement for overhead adjustment.
11. An "enhanced" turbo charger.
12. Bosh CP4.2 fuel pump to increase injection pressure. [This pump is controversial]
13. It is 60 lbs lighter
14. The maintenance interval on the breather filter has gone up to 75,000 miles.
15. The anticipated life of the engine is such that at 250,000 miles 10% of the engines will need a rebuild and at 350,000 miles 50% of the engines will need a rebuild.
16. A more efficient cooling system to handle the higher heat
17. Increased cylinder pressure

Watch this video: Rod Romain explains the differences in the HO. Here is a summary of what's stated in the video:

1. They increased the strength of the connection rods by going to a higher strength alloy.
2. They increased the strength of the crankshaft by going to a higher strength alloy.
3. They switched to a Compacted Graphite Iron (CGI) block.
4. New heads.
5. The turbo was improved for airflow (primarily on the compressor side).
6. The fuel pump is a new high pressure pump [Bosch CP4.2]
7. The injector lines were improved.
8. The engine water adapter and water outlet are both made out of aluminum instead of cast iron to save weight.
9. They went to a hydraulic lash adjuster. It is quieter, and it doesn't require a rocker adjustment at 100,000 miles.
10. Overall, the weight was reduced by 60 lbs.
11. They beefed up the Aisin transmission. The shift schedule was improved [this is controversial].
12. They beefed up the transfer case.
13. The front and rear drive shaft joints are larger, and they went to more of a CV-style joint with a slip-in spline. It is "more robust."
14. They reduced Noise, Vibration and Harshness (NVH) control with new dampers.
15. The exhaust hangers were redesigned.

Cummins' web site states states these improvements:

1. A Compacted Graphite Iron (CGI) material for the block allows us to increase the cylinder pressure capability while reducing the overall weight by almost 60 lbs
2. A new cast-iron cylinder head containing high-temperature capable exhaust valves actuated by all-new hydraulic lash adjusters in the block eliminates the need for valvetrain adjustment service intervals
3. The heart of the engine is a higher-strength alloy crankshaft with a 10-bolt crank flange driving newly-designed forged connecting rods and new bearings which transfer power from the low-friction ring-wrapped pistons
4. A new larger Cummins Holset variable-geometry turbocharger optimized with heavy duty bearings, and a new compressor-side housing is a key ingredient in the new ratings, pumping 33 pounds per square inch (psi) of fresh air into the engine
5. The new fuel-delivery system includes a new 29,000 psi (2,000 bar) fuel pump and fuel rail with Cummins Filtration “filter in filter” NanoNet® technology

As @brutal stated, the HO engine also comes with the 12" rear end (code AAM).

I think you need to go back and watch those videos again.

Those features and enhancements apply to both the SO and HO since 2019. All are differences from the previous generation 6.7L.

The TFL guy made it initially sound like HO only in the first comment in the video, but goes on to talk about the HP and TQ numbers for both versions.

 

[thestuarts]

I think you need to go back and watch those videos again.

Those features and enhancements apply to both the SO and HO since 2019. All are differences from the previous generation 6.7L.

The TFL guy made it initially sound like HO only in the first comment in the video, but goes on to talk about the HP and TQ numbers for both versions.

The regular (non-HO) engine has some of those features, but only the HO has all of those features. Are you suggesting the only difference between the two engines is the ECU tune? If not, what are the differences?

 

[thestuarts]

Torque management is more noticeable with the 68rfe than the Aisin.

Ram has officially stated torque is not limited with the HO+Aisin. Here are the videos:

• Rod Romain, the chief engineer of RAM, said, "Now, first gear has 100% of 1,000 foot pounds of torque."
• Jim Morrison, VP of RAM, said, "Yeah, we are not scrubbing any of the torque. It is available right off the get go. It really helps get the big trailers moving."

Maximum torque is available at 1,800 RPM, so 100% torque is available as soon as the engine reaches 1,800 RPM.

I am aware many people dispute Ram's claim, but I've not seen any evidence other than speculation.

 

[thestuarts]

I think you need to go back and watch those videos again.

Those features and enhancements apply to both the SO and HO since 2019. All are differences from the previous generation 6.7L.

The TFL guy made it initially sound like HO only in the first comment in the video, but goes on to talk about the HP and TQ numbers for both versions.

I watched the video again. Andre at TFL asked Rod Romain, "How does the new Cummins High Output differ from the outgoing one?" Rod then lists all the features for the HO.

 

[Brutal_HO]

The regular (non-HO) engine has some of those features, but only the HO has all of those features. Are you suggesting the only difference between the two engines is the ECU tune? If not, what are the differences?

As I already stated, pistons and injectors are what everyone is saying.

There is no significant difference between the 2019-2020 SO and HO engines.

Your reading too much into a couple marketing videos inaccurate assumptions.

Go look here: https://www.cummins.com/engines/cummins-67l-turbo-diesel-2019

ETA: CP4 repair kit has a single part number so that rules out injector differences. Tuning and more boost and as said, pistons.

SO compression = 19:1
HO compression = 16.2:1