We took delivery of our E350 Sportsmobile class “B” motorhome in April of 2005.
It is equipped with 6.0L PSTD and five [6] speed Torqueshift transmission.
Differential gear is 4.10 on Hankook 245/75 R16E tires turning {683 RPMi.}.
As a result of this combination the engine runs {2000RPM @ 60MPH}, right in the “Sweet Spot”.
Our SMB RB15 is used 35% as general transportation and 65% for towing our travel trailer, {20,000GCW}.
Being interested in experimenting after our 2006, [70 day 7500 mile] tour of the South and West I wrote several diesel performance forums.
Responses were mixed ranging from “You’re doing great, change nothing” to "You’re a prime candidate for major modifications."
Being confused by all the varying replies I decided to change nothing except driving habits while towing.
What follows is a report on performance.
Rather than try to outguess the computer I put the transmission in OD and set the CC @ [60MPH}.
IS ANY IMPROVEMENT POSSIBLE?
Well folks;
Got my E350 6.0L PSTD SMB RB15 back with new pillar mounted gauges so I'll be able to keep track of Transmission Temperature and Exhaust Gas Temperature on our extended winter trip.
We're hopefully departing Jan. 26, 2007 for a leisurely trek South through Ky., Tn., Ga., and Fl., then West through Ala., Miss., La., Tx., N.M., to Apache Junction, [Phoenix], Az., and return.
LATEST UPDATE
We've returned home from our "Annual" winter tour of the South and West.
We traveled to Southern Kentucky for a week, then Southeast to {Augusta} and {Savannah} Georgia for three days each. Two weeks in Fla. @ Lakeland, Silver Springs and Ocala.
Next we went West to Ocean Springs Mississippi where we were unexpectedly caught up in a Mardis Gras parade and got buried in {15 LBS of} beads.
We blew a tire on the travel trailer in downtown Houston at rush hour, [another story in itself] on our way to Corpus Christi, Texas. After a week in C.C. and a set of new TT tires, We took 6 days to get to Apache Junction, Arizona, with a stop at SMB Austin for some very minor warranty repairs.
We left Apache Junction three weeks later.
We meandered East on I 40 through Az., N.M., Tx., Ok., Ar., and Tn., to Nashville, North on I 65 to Bowling Green, Ky., East on Ky. 80 [future I 66] toward I 75.
Stops throughout Southern and Central Kentucky took up another 9 days.
The trip was mostly uneventful except as noted above and below.
Transmission temperature shot up to 195* during traffic jams, construction zones, and mountain driving, particularly through the Salt River Canyon where the speed limit was occasionally {15 MPH} and manual shifting was needed to maintain control on downhills and then get up to speed on uphills.
This caused the transmission to heat up to, but not beyond {195*}, whereupon the cooling system promptly brought it back down to {175*}, measured post cooler.
It was also in the canyon that the pyrometer reached its highest recorded temperature of {900*} measured post turbo.
At no time were either of these temperatures surpassed nor were they sustained for more than a few seconds.
We traveled 7300 miles through all types of terrain, leaving the transmission in OD and using Cruise Control to maintain speed.
Only once was it necessary, [because the cruise control couldn't hold the set speed], to slow to 45 MPH in third gear on a {10 mile long 7% grade} hillclimb in New Mexico.
We were heavily loaded with the E350 6.0L PSTD SMB RB15 Motorhome and trailer weighing {20,000 LBS CGW}, yet we again averaged 10 MPG.
Averages: towing {20,000 LBS GCW} in mountains, {6.5 MPG}. Towing {20,000 GCW} in flatlands and cities {10 MPG}.
City {7,500 LBS GVW} light, {12.5 MPG}. Highway {7,500 GVW} light {16.5 MPG}.
Having those gauges relieved me of a lot of concern and showed that the vehicle is capable of taking care of itself in most all situations.
There was never a serious "lack of power" concern and the cooling system worked phenomenally in my opinion.
There will probably not be many changes to our E350 6.0L PSTD SMB RB15 Motorhome in the near future except maybe more gauges.
A new larger trailer is in the planning stages possibly before the next trip.