hey gang,
made a 430 mile trip with my 20 ft trailer from NY to Ohio a few weeks ago in my 94 2wd 12v, & wasn't as happy with the mpg as I am when driving just the truck lol. Avg 65-70 mph, got about 15-17 mpg.
The trip has alot of slight to medium inclines, up & down hills driving, so I was into the boost more than I cared to be. It avg 5-7 psi at reg driving, up to 10-12 psi on hills I tried to minimize it with my right foot, but I got to thinking of how to get better mpg with a bit of a load.
When I just have the truck bed loaded it gets great mpg, but pulling a double axle 20 ft lawn trailer not so much, even when the trailer is empty.
Would I need a bigger turbo to stay out of the boost on the highway, or maybe more fuel, i.e. more aggressive fuel plate, etc.?
Thanks

 

Neither of those options will help you gain mileage. The turbo would likely decrease your mileage, as you would be using more fuel to try and generate boost, and would be hazing while driving (depending how large you go, of course). Otherwise my S480 single would be a mileage king! Fuel plate has no bearing on mileage when its not in contact with gov arm. Slowing down will be your best mileage increase. Aerodynamics is whats hindering you with the trailer, not power.

 

15-17 is actually pretty good pulling a trailer.
Over 50 mph aerodynamics takes the biggest toll.
Good read> Cummins Secrets of Better Fuel Economy

 

currently I have the upper grill blocked off for better airflow around the front end, bigger skinny tires in back to give the front end some rake, and to keep the rpm's down on the highway. Also have the mirrors pulled back a bit & the windows usually mostly up to reduce drag. At 70 mph I'm at about 1900-1950 rpm

 

When I tow I try to keep it a little below 60 mph. Torque peaks in the Cummins at about 1,600 rpm. which in my truck is about 56 mph. If you're running 70 mph, you're making less torque and thereby using more fuel and also having to deal with more wind resistance. Add these things up and 15-17 mpg is probably all you're going to get.

Also, if you tow with the cruise control on you'll eat fuel going up hills. I don't use my c.c. while towing in hilly country. I speed up going down the hills and only give it enough pedal going up the hill to keep the boost below 10 psi.

 

I used to get 12 - 15 towing our 34' 5h wheel. After installing a set of Bosch injectors that supposedly give an extra 75 horsepower that has dropped to 9 - 12. Sounds like more horsepower = more fuel used = lower mileage. Boost stays around 8 - 10 psi on fairly level roads.

I had figured if I kept the speed down and watched the boost injectors wouldn't make much difference in mileage. They seem to have made quite a difference.

Still get 20 - 21 empty cruising 70, boost hangs in about 5 psi.

 

15mpg on this trip below, 21mpg unloaded with a light foot

 

I got 11.5mpg on my 95 if that helps...but I was pulling 12,000 pounds up grades too.

 

Back in 2005, as we were moving back to Colorado from Oklahoma, I discovered how much effect aerodynamic drag has on fuel mileage. I was pulling a 7K-lb rated 18' car hauler trailer that I'd built 6' tall walls (sides, front and back with tarp-covered open top) to transport all our household goods. The first of 3 trips I loaded it heavy (I sure it was over the 7K rating). I was running Interstate hi-ways nearly the whole way at 70+ almost the whole trip. At the destination end we unloaded all the contents. Being tired and needing to get back to OK quickly for the other items I left the walls up and traveled the same route back. I was surprised that I got the same fuel mileage on the return trip as I had the first leg, especially considering the fact I was running loaded, against a headwind and climbing elevation (from about 900 to 6000 ft). The next round trip I disassembled the walls for the return leg, laying them flat on the trailer bed but ran the same speeds as before and was amazed at the fuel mileage improvement gained. I thought the weight would effect mileage more, but discovered the drag created by the tall trailer walls made the most difference.

 

Sounds like it's doing pretty good to me. Empty, ~35 mile one way trip to work, generally open country two lane hiway, running generally 62 mph, I get over 19 every time. Usually in the low to mid 19's. Stock truck, 285's. I put my boat on, 1860 aluminum, and pull ~30 miles to the lake and back it will drop that tank to ~18.5 mpg area. I pulled a FEMA trailer to LA back after Katrina, open interstate, running 65-70 mph and I got around 10 mpg it seems like. Big, big difference. My mpg drops significantly at 65 and over.

 

I usually get between 22.0 & 23.0 - that's mostly highway/freeway driving, with some street driving and some afternoon stop-n-slow traffic. I try to keep boost at/under 5 PSI when accelerating, coast up to lights, and (like Robert Rausch) use momentum-preservation. Last two tank-fulls were both over 23.0, though, and I've gotten 24.x once driving out to West Texas on open road.

These numbers are all without trailer, though the 24.x was with a full bed of camping gear for vacation. Wind resistance makes a huge difference, and speed plays into that. I don't recall where I saw this, but as speed increases the wind resistance factor increases by more than the speed increase - the faster you go, the aero resistance is (much) greater.

 

yeah I hear ya with the steady pedal. I want to slap someone everytime I hear or read "save fuel thru controlled speed!".
NO, its save fuel thru controlled pedal, moron. I gently speed up going down hills & keep the pedal steady going up until I'm over the hump, then carry on.
I always read that the sweet spot in the torque curve was around 1800 rpm; hmmmm

 

exactly, its all in the pedal! I often get <20MPG in my CTD and I once made 58 MPG (gps verfired) in my mechanical pumped VW diesel http://www.youtube.com/watch?v=yo-YUR1_DaU
just cruseing 40-60mph on country back roads with a light pedal with the car and its tires in top shape and these modifications:

Rear drums adjusted to zero drag
tires @ 45psi
fresh wax
light weight snythtic trans and engine oil
Belt removed from AC pump
never went past half throtle-its a non-turbo

Sure cant beat that for a economy car! I paid $40 at a yard sale for the diesel VW as they tired for years to get it started with no luck (burned up 50A glow plug fuse) and it gets better mileage than my inlaws new $30,000 Prius And im the one who barly made it threw math in highschool

 

Haha I wish I could say the same about my '01 Jetta tdi. We've put 50,000 kms on it in the two years we've had it and I've dumped in over $5k in repairs! No labour, I do my own work. It's never been insured for more than 5 months at at time 'cause it's always broke. Car is for sale. We drive the CUMMINS instead. It's much much cheaper in the long run, even though the tdi averaged 61mpg. When you do the math, it costs me around $100 a tank plus fuel and insurance to drive the stupid thing. Never again. Ever.

I average 24mpg hwy (Canadian) driving ~55mph on my 12 valve. Ya, I know I'm slow. My head is ported and timing is just shy of 16* - these added 4mpg on the average. 15-17mpg with a trailer is nothing to complain about. The Cummins might be one of the most efficient engines out there, but it still uses fuel to do work!

 

That's good milage. See my sig below. With my Lance I get 13-14 mpg. Add the boat and I get 13-14 mpg. All at 62 mph.