Let's see if I can answer everything in one go here...
In no particular order:
Yes, a weight distrubting hitch would probably help a bit. Not all that much though I think. Most of the use for a wd hitch is keeping the rear from squatting too much / front end getting light. Squat doesn't affect that much, and with the diesel there's not much worry about a light front end - with this load I had 3080# on the front vs 3380 with just the empty trailer. 2nd load I did this weekend (17.5 GCW) I had 3100# on the front loaded vs 3500 light. That was with ~1750lb tongue weight.
A swap bar would probably help more than a wd hitch, but then the sway issue was only really a problem for this one run and mostly due to the weight / high center of gravity / sheer size.
A gooseneck would for sure ride better. I was actually a rude shock to go back to the bumper pull since pretty much the only thing I've been towing in the past year has been my gooseneck horse trailer which rides and handles much much better.
On the other hand, the bumper pull is what I've got, and for what it is, she does quite well. Most of the time I'm running a fair bit lighter, it's just odds and ends that really get heavy. The official GVW on the trailer is 12.5k, and light weight is about 4. I try not to put more than about 6k on the trailer, which gives a GCW of ~17k. With that load it handles pretty well and I'm comfortable with it. Nice thing is that the trailer took that weight without complaining. It's an old Zieman equipment trailer and built heavy. Course, it also looks like someone abused that a fair bit, since at some point they broke the entire tongue off and bent both axles pretty nicely. My guess is they where hauling a full up backhoe or similar. But she does good for what I need a flatbed for.
Helps having new trailer brakes too. Never had any worries about stopping, though had the cable come loose or something it would have been a different story.
Getting it on was (fairly) easy - jacked the front up high enough to clear the dovetail, set it on a couple 2x12s and rigged my 4k winch from the front of the container to the front of the trailer. More or less just sort of slid right on up there.... Mind you, that was empty - empty container is only about 5,000 lb. After it was on the trailer I stuck another ~5k of junk in there.....
EGTs on this rig aren't bad, but then I pretty much drive off the boost and egt - could probably get them up there is I just put it straight to the floor and stayed there. I usually see 1050-1150 pulling and will creep up to 1200 on a real hard hill. Seen 1250 a few times but it's usually from the speed & boost starting to drop off before I let off the petal. She'll make 19-20 psi boost from about 1800 rpm up and it spool up nicely. Not sure how it compares to the hypermax honestly, but it works well for me.
Now, I'm still somewhat shy of 10k miles on her, so it's certainly possible that the downside here is that I'll cook the motor before too long.... hopefully not, but worth considering.
I also still haven't gotten the intercooler fully setup yet - that can't be helping matters any.
Coolant and oil temps seem pretty controlled as well. I saw up to about 225 for coolant and 235-240 oil pulling cajon with the container with the outside temp about 70-80. This weekend at 17.5k I don't think I even hit 210, though it was cooler and damper. I do have a serious heavy duty fan clutch though which helps a ton.
Got to dyno this rig one of the days - curious what I'm getting for power. My guess is somewhere around 300hp flywheel, but that's pretty much just a guess. No real experience driving a newer truck but I'm guessing we're about even with a late 7.3 psd. I can say with certainly that I can go up a hill with this rig at 17k gross faster than a NA idi empty.
This was this weekend's run:
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