A Little Towin Going On, Long Post
 

I recently completed a 4000 mile hike with the Fifth Wheel in tow. Here are some ratings for the truck.

Front Axle Max 4,750 lbs
Rear Axle Max 9,300 lbs
Max Gross Combined Weight 23,000 lbs

Truck on Scale with 34 gallons fuel 7,520 lbs includes Aux Fuel Tank, Fifth Wheel Hitch and rails, Bed Liner, Head Ache Rack, and Tailgate and a bunch of stuff under the rear seat. I’m out of the truck.

Front Axle 4,040 lbs.
Rear Axle 3,460 lbs.

I stopped by the local Moving and Storage scale and weighed the truck and trailer the morning I left. I was short about 4 Gallons of fuel when weighed. 101 gallons on board. With me and the wife in the truck, GCW 22,880 lbs.

Front Axle was 4,700 lbs.
Rear Axle was 6,980 lbs.
Truck Weight 11,680 lbs
Trailer Axles (6,000lbs each (2)) 11,200 lbs. Trailer Max GVW 14,030 lbs.

I forgot to get out of the truck with the wife after the scale paper was printed. I have to guess at the actual pin weight. The difference between the Trailer GVW and the axle weight is 2,830 lbs. Otherwise pin weight calculates as 3,520 lbs.

The Trip

Departed on 30 August and returned 24 October 2010. Tow speed was 65 mph. (Trailer Tire Ratings, Goodyear Marathons Load Range E) I was unable to make the first stop at Thousand Trails Chesapeake, Va. due to Hurricane Earl.

I had the auxiliary fuel tank turned off and stopped twice for fuel to see what mileage was. Both times it calculated about 10.7 to 11 mpg.

We diverted west to TT Lynchburg, Va. I ran the Juice on the Tow Position. I don’t turn on the Juice until I’m up speed. Coming up I-95 it was apparent, there was lots of power. I did not see how much until we headed out I-40 off I-95. There were some long grades which the truck was pulling without even hitting 1100 degrees (EGT’s). Boost was running around 17 psi most of the time. The only thing moving up was the engine water temperature. Even the transmission temp was doing good, at about 190. Tranny ran as low as 165 with the cooler air temp later in the trip.

After leaving Lynchburg, I headed out RT 460 to Roanoke and up I-81 headed north. The grades on 81 were longer and stepper than on route 40. Boost was up a little, EGT’s still under 1100 degrees. Running with cruise control on, set at 65, I was blowing bye cars, trucks, and other RV’s on the hills. I was impressed. I was able to accelerate up the hills when needed to move into the show off lane for passing, and get right up to 75 mph without any problems with EGT’s. Boost up to 27 to 34 psi. Using the Edge Owners Manual it indicated I was running at 365HP and 730 FtLbs of Torque. That could be a guess as well. The truck was running really good.

I did some running in areas were the speed limit was 55 mph with some long hills. I never experienced any downshifting at 65 mph. At 55 and the Edge on Tow, It would downshift to third with the cruise control on. So, to me, RPM’s are key to making the load move in 4th gear without a downshift. I ran with the O/D off a couple times to see what the low speed pulling power was. It was impressive at 55 mph on some really good hills were the speed limit was 55 or less.

Coming home, I departed TT Chesapeake in Gloucester, Va. with 103 gallons of fuel. (Indicated on Trax II Fuel Monitor) The Truck ran 820 miles on 72 gallons or about 11.3 mpg. Trucks range towing is estimated to be 1093 miles at 96 gallons used.

I had one small problem with the Triple Disc TC. When going into fourth the lock up was hard most of the time. The lock up in 3rd was smooth without any jerking. I began to run third up to 2500 rpms and then backed off the pedal and let it transition to 4th withoutany banging or harsh lockup. I’ve contacted the builder to see what can be done to eliminate the problem.

Cummins says I should be running at 2150 rpms at 65 mph for the best towing power and mileage. At 65 mph I’m turning just a little over 2000 rpm. 2150 rpm’s would require a 4:56 gear set with the 48RE in 4th gear. There is a person on the Carriage RV Forum, that pulls a trailer a little heavier than mine with 4:56’s and get close to 13 mpg towing and 16-17 mpg running lite. That’s with the 48RE. If I were to Full Time in the trailer, I would change the rear to 4:56. I can see that combination would be great in the real mountains out west. I also need an Exhaust Brake and some Billet Transmission parts.

I’m sure this truck would pull a 16,000 lb rig without any stress on anything. Trailer and truck brakes worked good together. I can’t tell you yet if the Turbo Wing helped out with mileage, but I can tell you, it’s a good bug deflector. It needs to be raised some so the air will actually go over the top of the trailer. I have a bug line about 2ft down from the top on the front cap. I will need longer struts for the wing.

Dave

Good write up. Sounds like a great trip other than Earl causing a slight change of plans..

Hey Dave,

As usual, good stats. You are sooooo festidious. [laugh]

I agree with you on the pulling - - my total rig with both of us in the truck, full fuel (85 gallons) and loaded for a 5 month trip is about 24,000 and the truck handles it well. I have the 4.10 rear end. I consistently have averaged 12.7 on my long trips. My computer is always about .1 mpg off from hand calc. So, I am a bit disappointed on your mileage. I do not use the cruise except on flat roads and find that can add up to 1 mpg. I don't push it up the hills like the cruise will and I let it creep up a bit coming down. This seems like it is averaging about .5 mpg more on hilly roads than the cruise will give me.

I do not have any enhancers and still find the power to be very good on this truck.

Bob

The power for me is great esp with the little bitty trailer (compaired to you guys) that I drag around. I sometimes wish I had the 4.10 rear end when I am in areas that limit speed to 55 but in the 65-70 mph range the 3.73 is around 2100 rpm which is perfect for what I am dragging. Sometimes though, I wish I had the room you guys have once I get parked.

Your setup with the NV5600 has a little more ratio in and rpm's at 65 mph. My previous truck with the NV5600 and 3:55 gears, did really well with my trailer except for fuel mileage. It was always 10mpg or less and had no room for a fuel tank with the GVW 1500 lbs less than the 06. As far as fuel mileage with this truck, you gotta remember the common rails, later than 04.5 are wasting fuel with the third injection cycle, where your truck only has two events. The 03-04 Dodge have the best fuel mileage of the common rail diesels even with big rear gears. They are also down on torque a little.

Most of the guys on this forum report about 11 mpg with 04.5 and later 5.9's trucks while towing. So I don't feel to bad with mine mileage.

Its possible, off the cruise control it could be a little better, but I found when I did come off the CC there was not much difference in any of the readings I was seeing on the Attitude in way of EGT's and boost. So, I don't think it will make much differance off the CC with the Juice in tow mode. Now running in the stock position, it could show some increase since the truck will be down on power using more of the fuel pedal to keep up. I have a family member that tow a Cari Lite with an 05 NV5600 and averages 12.5 mpg. He runs around 60 mph or less.

This was the first time I had the rig on the road at full load since I aquired the 06. The only thing I left home was the 4kw Genset. Left it for the kids in case a storm came thru.

As far as Enhancements go, the setup I have is awsome when towing. I don't think any stock truck pulling the same size load can stay with mine on a hill or straight out. Tow is the number two button on the Attitude/Juice. The next button will yeild 770 ft/lbs of torque and 385 hp according to the Juice Manual.

The Tranny is the weak link in the truck. I think with a 4:56 gear, I would be able to run that button.

As Far as Big Dogs go, they are bigger, heavier, good looking, and they make there owners feel superior on the road. Can't wait for one of those guys to get froggy on the road so the little 5.9 can jump.

My Avatar really does not show any diffinition so here it is a little bigger. Click on it for a better look.

Dave

I was playing around one day (while not trying to get anywhere fast) with setting the cruise, flat road, no traffic and running 50 in 6th, then doing the same in fifth - - - - oh yeh, this is all with 16000 pounds hanging around behind me. Trying to see if running up the rpms with the same load made any difference in mpg. I would reset the computer with each set and run about 10 miles. I know, not many miles to try and get a good reading, but it was a start. I was quite amazed that it made little to no difference. Now if I did it at 60, then the fun started. Once that little round thingy called a tach starts slipping over the 2300 mark, my mileage takes some serious declines in a hurry. I did the same thing on a good long incline where I could hold sixth at 60 mph with pedal almost to the floor. The next time over the same long incline I held 60 in fifth - - mpg increased about .8. I know, again short distance with little reliability, but it did give some interesting stats.

I have toyed with the idea of adding a juicer. I am sure there are some times it would be nice, but I am quite happy with the setup, no strain on anything and I REALLY do not have to be the first to the top of the hill. Still -- - - ????? [laugh]

Nice looking setup, Dave.

That is a nice setup. Did you ever do a mpg study without the Turbo Wing?
Thats my thinking too. But I still kind of want one. I havent even gotten around to installing the Raptor fp that I bought last June. X-mass is coming up, maybe Santa will be good to me.

the way to set the wing is with your manifold gauge. adjust it up a little at a time until you see the pressure starting to creep back up and set it in between. the best exhaust brake is the bd. the only good trailer brake controllers are the smartbrake and the maxbrake. if you will do the following you can get 13.5 mpg the auto is going to cost you 1 mpg over a good g56. but 13.5 is not to bad. your truck has in cylinder egr. to get rid of it you need to change the cam to a pdr or colt. at the same time change the nozzles to ddp 35 hp, they do not advertise them but will supply them. the reason for the change is not for extra power but for three other important reasons. in fact with yous auto we need to keep the power to a minimum. next change to the smarty jr and set on default tow and last get a 5" turbo back pipe kit from fbd and a m090072 resonator and m090535 or m101181 muffler and 4 clamps from ryder truck parts. this also lowers your egr by300* and keeps the oil cleaner

Very nice report, CoastalDav. Numbers speak.

As to fuel mileage one would think it would be better, if only slightly. First things I always think of are trailer axle alignment, brake drag and tire pressures on both vehicles (using truck manufacturer and tire Load Range numbers to match scale readings).

Leaving off the CC is not worth the small gain, IMO. Driver attention is better spent with distance and mirrors, etc. Best road speed for mpg is always slower, so that offsets CC use (and todays CC is so much better than the 1960's or 70's I never think about its use).

Where do you get the figure: 2,150-rpm "optimum" for TQ/HP mix?

Fuel mileage is always better at a slower speed than 65, so why not set the CC lower, but take a run at the hills when necessary.

I liked carl48's comments on the wing. Also liked Rednax's question "Where do you get the figure: 2,150-rpm "optimum" for TQ/HP mix?"
I don’t have a wing---yet, so the setup Carl mentions will be very helpful once I get one. As far as the 2150 rpm's posed by Rednax: For me, 2050 to 2150 gives me the best mpg and coolest running engine (on the stock gauge). I am going to get some better gauges when I install my Raptor fp. However, for the time being I am going to try to keep my RPM’s at 2100 esp when going up long grades.

Sorry for the delay in answering your questions. The Forum has not sent anything letting me know replies had been posted. Don't know whats with that.

Anyway to answer the question as to the RPM needed, it comes directly from the Cummins Web Site addressing gearing for trucks at a given speed. I used 65 mph. Thats what the trailer tires are rated for. Please see;

http://www.powerspec.cummins.com/sit...ng/gearing.htm

Use ISB as you might already know.

I have not pulled the trailer at full load without the wing in the past. Next time out I plan to do that, with the Aux Tank off to see what mileage is. That may not happen untill next April or May since I don't go north of I-10 between now and April.

This I can tell you about the Turbo Wing. I towed a good size airboat over to St. Martinville, La after the trip. (low profile tow) My normal mileage towing a similar boat is between 7.3 and 8.4 mpg. You may have seen my post from last spring with a picture of the tow. With the Wing for the tow, I got 10.9 mpg going over and got my butt kicked coming back getting 13.3 mpg with no tow. Without the wing, I normally get 19 mpg. So the wing is a load. I have not done any calculations yet to see what the drag is.

As mentioned eariler the air does not get over my fifth wheels front cap. So raising the angle may help the mileage. As I'm still pulling 3 ft of trailer in the open air along with the wings blast on the face of the cap. The strut that positions the wing has no more adjustment in it and no more length were another hole could be added. So if another can't be obtained from the manufacturer, I have to have it custom made.

Carl48 had some good info. As mentioned before mileage suffers from the 3rd event in the injection cycle, and the Tranny is the weak link in the drive train which I'm aware of. Keeping the main load off the tranny is the objective. Hence as mentioned before, I don't turn on the Juice until I'm up to speed and in O/D with the Triple lock up Torque Converter enganged.

I have read about camshafts and the 3rd event in the past. I think the cost outways the benifit. Keeping the load off the tranny, in my opinion would be better served by using a 4:56 gear with the Juice and some billet parts in the tranny. I would not change the gear ratio from 4:10 to 4:56 unless I go fulltime and towing is all I would be doing. I think >12.5 mpg is possible with the bigger gears at 60-65 mph.

Running at 55-60 mph with the Juice on Tow, results in downshifts. Not enough rpm. No downshifts are seen at 65 mph on the grades I've encoutered so far.

See post 639 for the airboat picture.

https://www.dieseltruckresource.com/...158300p43.html

Hope I answered everyones questions.

Thanks for the replies.

Dave

Good write up. Just wondering tho, going higher with the wing, wouldnt that just make you have a bug line between the truck and wing? Would moving the wing forward be the answer instaead of higher? Most likely getting allot of down pressure from wing.

Best to you.

I would have to add length to the mounting arms which can't be done. It would hit the roof of the truck. The arms run forward from the headache rack.
The structure that holds the wing would need to be much heavier than it is to do it.

Here is a pic Click on it for more detail.

You may have a 4:10 and not know it. 1900 rpm is 70 mph with 3:73's and 2100 is a 4:10 at 70 mph. This with 235x80x17 tires and a 48RE tranny.

I changed my rear from 3:73 to 4:10 last June and added the Triple disc torque converter right after that.

Dave

Hmmm, I will have to check it out. Thanks.