Took the plunge - Cummins to Hemi 6.4

mowin wrote:
How often are you planning on running those 7%+ hills and at those altitudes? So the Ram took a little longer. I would never run my rig with my foot to the floor for that long anyway.

Coming from a 2011 gmc 6.0 with 3:73's, I can safely say my 6.4 Ram with 3:73's easily out tow's my GMC 6.0.

I won't be very often and I am not saying its a bad truck; I am still seriously considering buying one. I just think it was a really bad move on Ram's part to not address the gear spacing. Even the F150 has better gear ratios.

How often are you planning on running those 7%+ hills and at those altitudes? So the Ram took a little longer. I would never run my rig with my foot to the floor for that long anyway.

Coming from a 2011 gmc 6.0 with 3:73's, I can safely say my 6.4 Ram with 3:73's easily out tow's my GMC 6.0.

Here is a brief example based on trans/rear end gear ratios. I know this isn't proof of anything but it shows the design flaw, in my opinion.

Ram 6.4 (420ft lbs @ 4000 rpm)

1st Gear 3.23= 1,356 ft.lbs x 4.10 rear= 5,559 ft.lbs
2nd Gear 1.84= 772 ft.lbs x 4.10 rear= 3,165 ft.lbs


Chevy 6.0 (380ft.lbs @ 4200rpm)

1st Gear 4.03= 1,531 ft.lbs x 4.10 rear= 6,277 ft.lbs
2nd Gear 2.36= 896 ft.lbs x 4.10 rear= 3,673 ft.lbs


So mathematically speaking the Chevy has 718 ft.lbs more in 1st gear and 508 ft.lbs more in 2nd gear. If my math is correct that is a substantial difference in torque to the rear wheels. If the Ram had the same gear ratios as the Chevy it would have walked away easily.

katoom400 wrote:

blderman wrote:

ib516 wrote:

blderman wrote:
Have you guys watched the Ike Towing Test posted this weekend? I have no idea how credible the testing guys are but I was pretty disappointed in the results. It's making me second guess the 6.4 now. The F150 Ecoboost towing just 1,800lbs less made it up the hill 4 minutes faster than the Ram. It appears the 2nd gear ratio on the 6.4 is really a poor fit for the engine. Thoughts?

You have to read the comment they posted a couple hours ago. They contacted RAM about the results, and got this response:

"We spoke with Ram and here's what they said about the slower Results of this Ike Gauntlet Run: "During the Silverado drive, you spoke negatively of the shift calibration. The tested Chevy was we assume hunting between 1st and 2nd, and ranged from 5300erpm to around 2800erpm, which you didn’t seem to like. The Chevy revved very high up the hill for extended periods of time, over 5000erpm.

Ram Truck “invented” the first gear hold feature – and calibrated it – to avoid gear hunting and driving at excessively high rpm’s.
Ike is a variable grade and we worked hard to develop a calibration that appropriately manages torque on the run and other grades.
We don’t want the truck to rev high for extended periods of time and purposely hold 4,200 rpm.

Bottom line – our truck performed exactly as expected by delivering a more comfortable hauling experience, better vehicle longevity and improved fuel economy. Time to the top of the hill is only one small piece of the driving experience and our engineers take a number of variable into consideration. Ask yourself if just over one minute is worth other negative driver inputs."?

I haven't experienced any limiting in any towing I have done, but then the highest elevation I have been to so far is about 7000'.

That is the response I would expect from an engineer. It's not like they are going to admit that 2nd gear is the wrong ratio. This definitely has my plans on hold till I can do more research. It would be interesting to see how it performs in manual mode.

would you really say 2nd gear is the wrong ratio, or is the shift logic a bit off?

Really, would you allow your truck to climb steep incline like that? I know they had to keep all things as equal as they could for the test, but in the real world, are you going to let the truck slow down to 30mph? No! you are going to manually downshift and let the truck rev! The Chevy was certainly at 5k for long periods of time, and that is most likely why it got to the top faster.

A more accurate test would have been to set points along the route where you designate down shifts for both trucks and see how they fair. the fact that the Ram held second for far too long doesn't bother me because I would never have let that happen in the real world.

IMO the only thing you could knock the Ram for is failure to downshift on an tough grade. BIG DEAL!

oh, one more thing for the guys bashing the Ram, watch the Chevy video @ 19:45 they start talking about how the truck should have downshifted and is holding the gear for way to long and they are down to 35mph.

So I would say if you have no clue know how to drive a truck pulling a heavy trailer, you would be better served buying a Chevy as it will downshift for you in case you fell asleep.

and no I'm not a RAM lover, I'm a Tundra guy looking at all the options for my next truck and I really think all of the big 3 are so close you just have to pick the one that appeals to you or fits your needs the most and you can't go wrong.

I want to first say that I am not bashing the Ram. My only hesitation is that I am moving from a diesel back to gas and I really thought this engine was going to perform better. Not saying it's a bad truck, I know it is WAY better than my current Ford and I look forward to being in a Ram truck again very soon.

Yes, I do believe the 2nd gear is too high. The ratio spread between 1st and 2nd is pretty large, with the Cummins it is able to power its way through due to the huge torque curve. The 6.4 cannot and that is why it slowly lost speed till it dropped back into 1st. If the engineers really programmed it to stay in first and limit it to 4,200rpm during extended heavy loads I think they made a huge mistake. I really hope that manual mode can override that feature. With stated power of the 6.4 it should have been able to handle that grade with relative ease compared to the Chevy 6.0.

blderman wrote:

ib516 wrote:

blderman wrote:
Have you guys watched the Ike Towing Test posted this weekend? I have no idea how credible the testing guys are but I was pretty disappointed in the results. It's making me second guess the 6.4 now. The F150 Ecoboost towing just 1,800lbs less made it up the hill 4 minutes faster than the Ram. It appears the 2nd gear ratio on the 6.4 is really a poor fit for the engine. Thoughts?

You have to read the comment they posted a couple hours ago. They contacted RAM about the results, and got this response:

"We spoke with Ram and here's what they said about the slower Results of this Ike Gauntlet Run: "During the Silverado drive, you spoke negatively of the shift calibration. The tested Chevy was we assume hunting between 1st and 2nd, and ranged from 5300erpm to around 2800erpm, which you didn’t seem to like. The Chevy revved very high up the hill for extended periods of time, over 5000erpm.

Ram Truck “invented” the first gear hold feature – and calibrated it – to avoid gear hunting and driving at excessively high rpm’s.
Ike is a variable grade and we worked hard to develop a calibration that appropriately manages torque on the run and other grades.
We don’t want the truck to rev high for extended periods of time and purposely hold 4,200 rpm.

Bottom line – our truck performed exactly as expected by delivering a more comfortable hauling experience, better vehicle longevity and improved fuel economy. Time to the top of the hill is only one small piece of the driving experience and our engineers take a number of variable into consideration. Ask yourself if just over one minute is worth other negative driver inputs."?

I haven't experienced any limiting in any towing I have done, but then the highest elevation I have been to so far is about 7000'.

That is the response I would expect from an engineer. It's not like they are going to admit that 2nd gear is the wrong ratio. This definitely has my plans on hold till I can do more research. It would be interesting to see how it performs in manual mode.

would you really say 2nd gear is the wrong ratio, or is the shift logic a bit off?

Really, would you allow your truck to climb steep incline like that? I know they had to keep all things as equal as they could for the test, but in the real world, are you going to let the truck slow down to 30mph? No! you are going to manually downshift and let the truck rev! The Chevy was certainly at 5k for long periods of time, and that is most likely why it got to the top faster.

A more accurate test would have been to set points along the route where you designate down shifts for both trucks and see how they fair. the fact that the Ram held second for far too long doesn't bother me because I would never have let that happen in the real world.

IMO the only thing you could knock the Ram for is failure to downshift on an tough grade. BIG DEAL!

oh, one more thing for the guys bashing the Ram, watch the Chevy video @ 19:45 they start talking about how the truck should have downshifted and is holding the gear for way to long and they are down to 35mph.

So I would say if you have no clue know how to drive a truck pulling a heavy trailer, you would be better served buying a Chevy as it will downshift for you in case you fell asleep.

and no I'm not a RAM lover, I'm a Tundra guy looking at all the options for my next truck and I really think all of the big 3 are so close you just have to pick the one that appeals to you or fits your needs the most and you can't go wrong.

ib516 wrote:

blderman wrote:
Have you guys watched the Ike Towing Test posted this weekend? I have no idea how credible the testing guys are but I was pretty disappointed in the results. It's making me second guess the 6.4 now. The F150 Ecoboost towing just 1,800lbs less made it up the hill 4 minutes faster than the Ram. It appears the 2nd gear ratio on the 6.4 is really a poor fit for the engine. Thoughts?

You have to read the comment they posted a couple hours ago. They contacted RAM about the results, and got this response:

"We spoke with Ram and here's what they said about the slower Results of this Ike Gauntlet Run: "During the Silverado drive, you spoke negatively of the shift calibration. The tested Chevy was we assume hunting between 1st and 2nd, and ranged from 5300erpm to around 2800erpm, which you didn’t seem to like. The Chevy revved very high up the hill for extended periods of time, over 5000erpm.

Ram Truck “invented” the first gear hold feature – and calibrated it – to avoid gear hunting and driving at excessively high rpm’s.
Ike is a variable grade and we worked hard to develop a calibration that appropriately manages torque on the run and other grades.
We don’t want the truck to rev high for extended periods of time and purposely hold 4,200 rpm.

Bottom line – our truck performed exactly as expected by delivering a more comfortable hauling experience, better vehicle longevity and improved fuel economy. Time to the top of the hill is only one small piece of the driving experience and our engineers take a number of variable into consideration. Ask yourself if just over one minute is worth other negative driver inputs."?

I haven't experienced any limiting in any towing I have done, but then the highest elevation I have been to so far is about 7000'.

That is the response I would expect from an engineer. It's not like they are going to admit that 2nd gear is the wrong ratio. This definitely has my plans on hold till I can do more research. It would be interesting to see how it performs in manual mode.

blderman wrote:
I would like to have the maneuverability of a short bed, but an 8' bed is nice for so many reasons that I don't think I could go back.

I love the handling and maneuverability of my short bed extended cab. I recently pulled the camper off since I am putting this one up for sale and have been driving it around more. I can get close to that with an extended cab F550 because the wheels cut sharper even though the bed would be longer: 6.75' to 9'. Most likely I will be going from my 19.25' truck to something closer to 24' and give up some of that nimbleness.

bucky wrote:
Sweet truck. I currently tow with a CTD but agree with comments about the initial expense and the increasing complexity of the emission era diesels trucks of all brands. I have an older truck with a Banks kit on it, so I'm at approx 325/650. A bone stock 24V would be a dog.
I would suggest getting at least 500 miles on it before you tow. That will seat/condition the ring and pinion properly and give a longer life. Towing too soon can wreak havoc on an axle.
As others have mentioned, that thing has to rev, don't let the noise scare you pulling a grade.

I will second the 500 miles to seat the ring and pinion before towing.

blderman wrote:
Have you guys watched the Ike Towing Test posted this weekend? I have no idea how credible the testing guys are but I was pretty disappointed in the results. It's making me second guess the 6.4 now. The F150 Ecoboost towing just 1,800lbs less made it up the hill 4 minutes faster than the Ram. It appears the 2nd gear ratio on the 6.4 is really a poor fit for the engine. Thoughts?

You have to read the comment they posted a couple hours ago. They contacted RAM about the results, and got this response:

"We spoke with Ram and here's what they said about the slower Results of this Ike Gauntlet Run: "During the Silverado drive, you spoke negatively of the shift calibration. The tested Chevy was we assume hunting between 1st and 2nd, and ranged from 5300erpm to around 2800erpm, which you didn’t seem to like. The Chevy revved very high up the hill for extended periods of time, over 5000erpm.

Ram Truck “invented” the first gear hold feature – and calibrated it – to avoid gear hunting and driving at excessively high rpm’s.
Ike is a variable grade and we worked hard to develop a calibration that appropriately manages torque on the run and other grades.
We don’t want the truck to rev high for extended periods of time and purposely hold 4,200 rpm.

Bottom line – our truck performed exactly as expected by delivering a more comfortable hauling experience, better vehicle longevity and improved fuel economy. Time to the top of the hill is only one small piece of the driving experience and our engineers take a number of variable into consideration. Ask yourself if just over one minute is worth other negative driver inputs."?

I haven't experienced any limiting in any towing I have done, but then the highest elevation I have been to so far is about 7000'.

larry barnhart wrote:
FLT has a new 6.4 towing test on you tube.

chevman

I posted that on here earlier today. Seems the test is deceptive since the Ram was carrying 2,000lbs more than the Chevy. I still don't like the 2nd gear on the Ram though.