Postcard from Arizona- 3

Main road looking across the dry camp area

Benson, AZ

We’re still hanging out at the SKP Saguaro Co-op RV Park in Benson, AZ. We were enjoying the stay so much that we even got on their hot list for getting a lease. We enjoy the park a lot because of the people and the activities available during the season (winter). But there’s a lot to be said economically for making this home base. Renting a site on a monthly basis is about $11/day and a lease (currently under $8,900 plus the cost of improvements) is a lifetime lease… no additional rent though there are maintenance fees and occasional assessments like road repairs or whatever. So we got on the Hot List and, after signing an annual rental agreement, moved to site #306 on the southern edge of the park where we will probably not have to move while we’re visiting this park.

Santa Fe, NM
We made a trip to Santa Fe for me to see the ophthalmologist. Santa Fe is also the location of what has become the money pit… our as yet unsold house. The day before leaving we got a call from the person watching our house. Seems we had water pouring out the back of the house. Oh joy.

Replacement bowl installed
Onyx was able to shut off the water and saw that the water filter we installed ahead of the on-demand water heater had burst. That could only have happened if we lost power to the electric space heater or if the heater (brand new before we left) had died. So our return was both timely and necessary.

While the repair of the water leak was a simple $39 fix, the cost of the water will be about $1,700. The leak amounted to nearly 100,000 gallons. I received a call from the Santa Fe City office that handles water billing and among other things was told there’s an appeal process available that will probably get us some relief, but we’re still going to have a very large bill.

News from the eye doctor was not so hot either as the pressure was up again… now at 27. I have to go back in 30 days (yet another trip to Santa Fe) to see if this was just a transient or if a change in medication is necessary. Bummer. In hind sight it was a good that we had already decided to not head for Clewiston, FL as we had been planning for the last year… it would have been even more disappointing to find out at the last minute we couldn’t go.

Dealing with diesel fuel cost

[ This part’s for me. I want to be able to remember in a couple years why I spent a lot of $$$ at Banks Engineering! ]

Another troubling development (you’d have to be dead from the neck up to not think fuel costs were going to rise) is the painful cost of diesel fuel. I did some digging on the internet looking for alternatives and, with a friend Dan Weigman doing the same thing for his 6.7L Cummins-powered Dodge, we shared what we learned.


It quickly became clear that the evil culprit is the diesel particulate filter- the DPF. There are options for improving fuel economy on the current crop of diesel engines- like replacement air intake & filter, larger exhaust piping, more efficient inter-cooler, and re-mapping the fuel injection will all offer some measure of economy. Until you remove the DPF, however, large gains in fuel economy are going to be unlikely.

As I understand the DPF that we have on our 2008 Ford (it has a 6.4L International engine), the process works by collecting unburned fuel (diesel particulate) on the exposed surfaces of the DPF, i.e. the DPF collects soot that would otherwise be dumped out the exhaust pipe. The thing about this soot is that (compared to a gas) it’s a solid and it’s heavy. Being heavier than air, it will eventually drop to the ground or collect on trees or whatever.

The capacity of the DPF isn’t endless, so something has to be done to clean the filter and that happens by periodically raising the exhaust gas temperature (EGT) in order to burn the soot. That high temperature is close to 1,300 deg F which causes the soot to turn into ash which apparently is carried out the exhaust instead of the soot. So, take your pick: either soot or ash plus CO & CO2).

The way they raise EGT to clean the filter is to inject raw diesel into the exhaust ahead of the DPF. When these super-high temperature gases hit the soot, the soot (incompletely burned fuel in the form of carbon) is turned into the ash I mentioned (I don’t know the chemical composition of the ash) plus CO + CO2. If I have this right, it means cleaning the DPF is increasing the amount of greenhouse gases over the amount otherwise in the exhaust as well as increasing fuel consumption in order to reduce particulate-carbon fallout. Other nasties like sulfuric acid have already been greatly reduced with the new low-sulfur diesel fuel diesel engines must use.

In any case, the cleaning process uses a lot of fuel. In our case, every time cleaning occurs, mileage drops by 0.1-0.2 mpg. And cleaning happens every 75-150 miles. The result is that previously more-efficient diesel engines offered today have been made to be less efficient than some gas engines when the truck is driven solo (not towing or not carrying a load). The modern diesel engine still produces huge amounts of torque under heavy load, so there’s really no reason to think about using a gas engine for towing/pushing a large RV. Put the fuel economies of the good ol’ days are gone.

The fixes available on the street amount to a pick-and-choose combination of 1 or more of 4 approaches:
  1. improve engine breathing (air filter, bigger exhaust)
  2. improve turbo-charger efficiency thru additional cooling of the compressed air to the intake
  3. improve fuel mapping of the mfrs engine management firmware (this mostly increases torque)
  4. get rid of the DPF and change the engine management firmware to stop cleaning the filter

The 4th option will probably cause a problem with the manufacturer if you’re still under warranty as we are. And, if vehicle inspections become a reality for small diesel trucks, the owner might have to pay a $1,700 fine for having modified the DOT/EPA (?) approved exhaust system plus have to restore the original design. It’s unclear what happens if you do any or all the other 3 changes (breathing, inter-cooling and fuel mapping), but we decided that was the route we would try.

I ended up choosing Banks Engineering as the supplier for exhaust system, air intake & filter, turbo inter-cooler, and fuel injection module. It’s not going to be a spectacular improvement since we still have the DPF, but we need to do something if we are to continue traveling with the dog house.

Show room at Banks Power House.

So, with neighbor & friend Mike Phelps as co-pilot, we drove to Azusa, CA to have Banks’ Big Hoss kit installed. Banks is a pretty large operation (something like 700 people working in 7 buildings) with a division dedicated to installation and repair (Banks Powerhouse). Check-in was at 6:00 AM and the shop closes at 3:00 PM, so we were there when they opened. Apparently we would have been out of there by 11:00-11:30 AM but for one small problem. Oue truck has a factory installed option of a roll-over ball gooseneck hitch. It’s made by B&W in Kansas and is a perfect match for our B&W Companion (5th wheel) hitch. Since it was a factory option, Banks had to get their Tube Shop involved (they manufacture the exhaust systems and the headers). banks hadn’t previously had a truck available to them to be able to make the necessary measurements, so our truck became a Beta test site. Almost 2 hours later we saw someone walking across the street with about 4′ of bent 4″ exhaust tubing over his shoulder. Another 2 hours and the truck pulled out for a test ride.

On the hoist at Banks Power Shop in Azusa, CA

We got a walk-thru on pushing buttons on the Banks iQ controller. The iQ is basically a PDA with a built-in GPS which monitors & controls the 6-Gun tuner, keeps track of data during operation and testing, computes fuel usage, and, with the right option + maps, will navigate. 

10-minutes later we were on our way to dinner and ready to watch the State of the Union Address. Next morning we headed back to Benson and watched the mileage computer like a hungry hawk looking for lunch. The #1 setting is Stock and sure enough it had about the same uninspiring mileage as before. #2 was the Economy mode and it was anything but economical.


The Customer Support Mgr. that did the run-thru had said to try all the modes because each truck is different and sometimes other modes work better. So up the setting went to #3 which is the first of the high power modes. As soon as I reset the mileage computer the display jumped to 27 mpg. The euphoria was over in an instant when I realized we were on a slight down-grade. Still, the mileage seemed to hang at around 20-25 mpg as we headed out of town.

After an especially steep grade (sign at the start of the grade: “TURN OFF AC TO PREVENT OVERHEATING”) I reset the mileage computer and left it untouched the rest of the way to Benson. That was about 400 miles of very gradual uphill driving from 500′ at the top of the pass to 4,200′ at the Benson turnoff. We were showing 18.2 mpg as we got to the park and shut off the engine. A similar trip with the stock setup had ended at 15.2 mpg, a net mileage improvement of 20%. I think we can live with that till the day comes we are pushed into getting a DPF-Delete kit.

Btw, Mike told me that he learned that letting EGT drop to under 400 deg F before shutting off the engine was supposed to be a good safety practice. That’s easy enough to add to routine-driving practice. Also, turning on the head lights (turns on the amber clearance lights) is supposed to drop the chance of an accident by 17%. Yet another cost-free improvement. Nice to have someone with a CDL riding shotgun!

A word of caution to the weary traveler… some sections of I-10 were miserable as we got close to LA. It appears that the concrete wasn’t set up correctly which leaves the surface with a near-washboard face. The suspension of our F-350 is pretty stiff which was enough to make many miles of the trip a trial!

That’s it for now. More later

About bruce10b

Celia and I are full-time RVers wintering (and now summering!) in Benson, AZ. The 2 bernese mountain dogs that initiated the name of this blog are gone but forever alive in our memory.
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