2500HD 6.0 First Tow

Breadbagel · September 12, 2015

yeah I will have to do that. I can deal with the gearing issue, it just might mean going slower than I would like to. I just wish visibility wasn't an issue.

Cowpie · September 13, 2015

I wouldn't say the 5.4 out towed the 6.0. I'm pulling the same trailer I did with the f150 and they both pull good. I just never had the gearing issue with the f150 where there is a huge difference in the rpms from one gear to the next. you can see the issue im talking about in the tfl video with the 2500hd.

That is true, but considering the 6.0L in the 2500 reaches 90% of peak torque at 2000 RPM, I am not convinced it is that critical. The curve has only a slight rise from 2000 up to max torque at 4200 RPM. There was no appreciable drop off of speed or lugging between shifts in the TFL test. If the curve was more rounded, then that RPM drop between gears might mean more. But, as evidenced by looking at the TFL videos, the 6.0L equipped 2500 totally knocked the socks off of the 8 speed 6.4L Dodge which had smaller RPM drops between gears, and was only 1.5 minutes slower up the pull than the Dmax equipped 2500. Given all of that, it is why TFL awarded the 2015 2500 6.0L with the Golden Hitch Award.

Breadbagel · September 13, 2015

That is true, but considering the 6.0L in the 2500 reaches 90% of peak torque at 2000 RPM, I am not convinced it is that critical. The curve has only a slight rise from 2000 up to max torque at 4200 RPM. There was no appreciable drop off of speed or lugging between shifts in the TFL test. If the curve was more rounded, then that RPM drop between gears might mean more. But, as evidenced by looking at the TFL videos, the 6.0L equipped 2500 totally knocked the socks off of the 8 speed 6.4L Dodge which had smaller RPM drops between gears, and was only 1.5 minutes slower up the pull than the Dmax equipped 2500. Given all of that, it is why TFL awarded the 2015 2500 6.0L with the Golden Hitch Award.

Hmmm. I don't know, seemed like I was up in the 6's and then it dropped to 3 or maybe 3500 and didn't have enough to maintain speed. I'll have to run it again someday and maybe take a video. that is if I ever get it back from service. approaching a week and a half now for an oil leak and this is the 2nd visit for it. the first visit they couldn't find the leak. The only reason I would ever consider getting the Ram is the fact that they still have the manual transmission.

Cowpie · September 13, 2015

I think it is a product of what you are running up to. If you run up to the 6's in RPM, you have less torque available than at 2000 RPM according to GM's own charts. It is the absolute rotational inertia that you are depending on at that point. Even if dropping to 3500, there is easily 50+ more lb of stock torque available at 3500 than at 6000 RPM. Even at 5000 RPM, available torque has dropped off to below 3500 RPM levels. Almost down to 2000 RPM levels. There is a substantive drop off of available torque after reaching peak at 4200. When you run up to those RPM levels and then shift, the motor does not have an instantaneous jump in torque either. There will be a slight delay for the motor to settle on power at a new RPM. This chart from the up fitter version of the L96, but torque curve is identical to L96 in the 2500-3500 pickups. The chassis up fitter version just has a lower HP rating.

Breadbagel · September 13, 2015

I think it is a product of what you are running up to. If you run up to the 6's in RPM, you have less torque available than at 2000 RPM according to GM's own charts. It is the absolute rotational inertia that you are depending on at that point. Even if dropping to 3500, there is easily 50+ more lb of stock torque available at 3500 than at 6000 RPM. Even at 5000 RPM, available torque has dropped off to below 3500 RPM levels. Almost down to 2000 RPM levels. There is a substantive drop off of available torque after reaching peak at 4200. When you run up to those RPM levels and then shift, the motor does not have an instantaneous jump in torque either. There will be a slight delay for the motor to settle on power at a new RPM. This chart from the up fitter version of the L96, but torque curve is identical to L96 in the 2500-3500 pickups. The chassis up fitter version just has a lower HP rating.

2015 6L L96.jpg

So if I shift at 4200 it should do better then? why wouldn't the transmission automatically shift at the best time when in tow haul mode?

Cowpie · September 13, 2015

Programming. Tune it and change the shift points. Even on heavy commercial truck automatics and automated manual transmissions, the shift points are generic and not always ideal for every application. Unfortunately, the pickup OEM's are not as generous with user defined variables that can be adjusted by the dealer like the commercial truck OEM's allow. In a typical heavy commercial truck, I have over 250 variables I can have the dealer select and adjust at my whim, several of them which are transmission related. The pickup OEM's have their particular desires in mind when they set the shift point programming the way they do. Some of it is legit, in that they are concerned with transmission protection. Some of it comes from more of a nanny mentality and the perception that they need to protect everyone from themselves.

I never implied shifting AT 4200, I only stated that racking up the RPM's you are claiming takes it well outside the efficient band of the motor. I know this is some what confusing. I am viewing it thru over 5 million miles of commercial truck driving. One has to learn their motor and the band it operates best. The charts gives a starting point that anyone should refer to right out of the gate. From there, they need to find that ideal range that Unfortunately also with this motor, the torque curve is not nearly as flat across an RPM band as is ideal, but even with that, there is really no appreciable reason to take the RPM's any higher than necessary, so that on the RPM drop with a gear shift, the torque at the new RPM is above 90% of total available torque. Over speeding the motor out side the efficient RPM range can have more negatives than any supposed positives, shifting included.

Breadbagel · September 13, 2015

what doesn't make sense to me is why shouldn't I be maintaining speed after shifting if the torque is higher at those rpms? I don't remember the exact rpms I was in but I know I'm close.

SMiller · September 13, 2015

Why do you guys keep saying 6,000 rpm? The motor defuels before 6,000rpm, you guys have not spun the motor that fast.

SMiller · September 13, 2015

what doesn't make sense to me is why shouldn't I be maintaining speed after shifting if the torque is higher at those rpms? I don't remember the exact rpms I was in but I know I'm close.

Because despite what some say horse power matters, the most power is where horse power and torque max out which I believe is at 4400rpm. You need the motor to rev past that point to prepare for the next shift or you would be way under the curve.

The real thrufh is that the stock tuning sucks and most of the time the throttle body isn't even 100% open. Tune a 6.0 and you would be amazed at what the stock motors is capable of with good trans tuning and 100% power.

Breadbagel · September 14, 2015

Why do you guys keep saying 6,000 rpm? The motor defuels before 6,000rpm, you guys have not spun the motor that fast.

you are right. it was around 5000 not 6000. I had to watch the tfl video again because my truck is still getting the oil leak fixed. I would be scared to tune the truck and screw it up even more and have it not covered under warranty.

KMK454 · September 14, 2015

I towed about 8000 pounds recently through the mountains of CO and UT with my CC 6.0 and had about another 1000 pounds loaded in the truck. It did just fine. About the only weird behavior was when I was cutoff and had to brake going up a steep grade and then had to get back on the throttle to safely climb in traffic. The 6.0 had plenty of power to get back up to speed (from 25 MPH back up to 55 MPH on a 6% highway uphill; I would have held it slow but there was a lot of traffic); the 6.0 held RPM in the 5200 to 5500 or so (redline) zone for what seemed like forever before upshifting... in reality, it was probably only 10 to 15 seconds, but since I'm not used to running that RPM, it seemed longer. It did send the transmission temp up about 30 degrees, but the downhill grade on the other side cooled it quickly. This may be completely normal behavior, though.

Otherwise, I never once felt like the truck was truly taxed or unable to handle the weight, and not just from an acceleration perspective. MPG was 9-12, with the variance coming due to terrain more than anything else.

Perhaps the best part is how good the 6.0 sounds, even with a stock exhaust. And when the trailer comes off, the 6.0 feels quick!

Unrelated - I experimented using tow/haul, but found it to be a bit unnecessary. All it really did was delay upshifts and on downhills, it would downshift more readily. I did like the time increase on the lane-change turn signaling, though.

Hockeylover86 · September 14, 2015

That is true, but considering the 6.0L in the 2500 reaches 90% of peak torque at 2000 RPM, I am not convinced it is that critical. The curve has only a slight rise from 2000 up to max torque at 4200 RPM. There was no appreciable drop off of speed or lugging between shifts in the TFL test. If the curve was more rounded, then that RPM drop between gears might mean more. But, as evidenced by looking at the TFL videos, the 6.0L equipped 2500 totally knocked the socks off of the 8 speed 6.4L Dodge which had smaller RPM drops between gears, and was only 1.5 minutes slower up the pull than the Dmax equipped 2500. Given all of that, it is why TFL awarded the 2015 2500 6.0L with the Golden Hitch Award.

It seems that Dodge has never been good at transmission calibrations with regard to shift-points.

Regarding the 6.0 vs dmax data, the test data shows the diesel over 2 1/2 minutes faster towing heavier. Either way the 6.0 was still extremely impressive given the high elevation.

Breadbagel · September 14, 2015

I towed about 8000 pounds recently through the mountains of CO and UT with my CC 6.0 and had about another 1000 pounds loaded in the truck. It did just fine. About the only weird behavior was when I was cutoff and had to brake going up a steep grade and then had to get back on the throttle to safely climb in traffic. The 6.0 had plenty of power to get back up to speed (from 25 MPH back up to 55 MPH on a 6% highway uphill; I would have held it slow but there was a lot of traffic); the 6.0 held RPM in the 5200 to 5500 or so (redline) zone for what seemed like forever before upshifting... in reality, it was probably only 10 to 15 seconds, but since I'm not used to running that RPM, it seemed longer. It did send the transmission temp up about 30 degrees, but the downhill grade on the other side cooled it quickly. This may be completely normal behavior, though.

Otherwise, I never once felt like the truck was truly taxed or unable to handle the weight, and not just from an acceleration perspective. MPG was 9-12, with the variance coming due to terrain more than anything else.

Perhaps the best part is how good the 6.0 sounds, even with a stock exhaust. And when the trailer comes off, the 6.0 feels quick!

Unrelated - I experimented using tow/haul, but found it to be a bit unnecessary. All it really did was delay upshifts and on downhills, it would downshift more readily. I did like the time increase on the lane-change turn signaling, though.

Sounds like we were in almost identical situations. I had about 1000 lbs in the truck as well and there was a long period where it was in the redline zone. I just had to keep it there to maintain speed until it leveled out.

Cowpie · September 15, 2015

Therein lies some room for exploring. Like using manual mode instead of tow/haul on an upgrade to control shifting a little better (i.e. allow quicker shifts than Tow/Haul does), and tow/haul mode on down grade for better braking control that it offers. Sometimes one has to be just a little smarter than the computer and be a little creative. There never really seems to be a great "one size fits all solution". All part of learning one's equipment and finding out how to get the most from it.