On the flats or very slight grades.........
Is it better to tow at 2400 rpms with the pyro at 700 degrees and 10 pounds of boost in 5th gear? or 6th gear (O.D.) at 1900 with the pyro at 850 and boost at 5 pounds to get the best fuel economy?
higher Heat = more fuel... but at 2400 rpms my injectors are firing 30% more than at 1900..
I have never tried to drive a whole tow trip one way or the other to check it??
Has anyone look at it like this? [img]/ubbthreads/images/graemlins/tongue.gif[/img]
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2001 F350 4X4 Crewcab Lariet, 6 speed ZXG1 Code
Edge Tuner Race setting,
Pyro, Boost guages
ATS BB Turbo
4" Turbo back
AH delete
AIS intake with fender mod
Zoodad
Map Sensor pressure regulator Max 26PSI
Exhaust brake
3.5" Lift 3.73 with rear locker
33" x 16.5 Tires on weld Scorpions
Towing 27' of Trailbay trailer 8500 lb
and Hauling a DR650, DR350, XR250R
My pull trailer averages 6800 to 7000 axle weight with 800 to 1000 pounds on the hitch. My engine is set to make 26.5 pound max it will on a hard pull creep up to 28. I hope my gauge is accurate at low pressure.
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2001 F350 4X4 Crewcab Lariet, 6 speed ZXG1 Code
Edge Tuner Race setting,
Pyro, Boost guages
ATS BB Turbo
4" Turbo back
AH delete
AIS intake with fender mod
Zoodad
Map Sensor pressure regulator Max 26PSI
Exhaust brake
3.5" Lift 3.73 with rear locker
33" x 16.5 Tires on weld Scorpions
Towing 27' of Trailbay trailer 8500 lb
and Hauling a DR650, DR350, XR250R
From what I recall, for best fuel mileage you want to have the engine running as close to it's torque peak when going down the road.
It's been awhile since I spec'ed a truck, so my info could be clouded by cobwebs.
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Cranky old guy with a '05 F250 C/C shortbed.
I'd opt for the 6th gear. Better fuel mileage. Those temps are fine as long as they are pre turbo temps. The reason the higher rpm is cooler is because you are pushing more air through the engine, I think.
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1996 F250 4x4 ext. cab, long bed 5 spd. 3.55ls, Tymar Intake, Tymar 4" downpipe and 4" exhaust. AIC, B&W turnoverball, EBPV brake, tranny temp gauge, boost gauge, and egt gauge. 235k miles and thousands of $$$$ in maintenance and repairs.
If, when you are towing at 1900, and you increase throttle, the speed immediately picks up, then you are not lugging.
If you are already at full throttle, or increasing throttle has no effect, then you are lugging and need a lower gear.
It is far better on these small engines to run them "light" and fast, then "heavy" and slow. Fuel consumption should not be that much different, and your engine will thank you for it.
These are not semi-truck engines, and they should not be driven that way. Even semi engines from just a few years back needed to be driven at higher RPM. The parts and bearing surfaces are small and operating at high RPM means light load many times a second vs low RPM which is heavy load fewer times a second.
But I agree, cruising, you can get better economy by running lower RPM, but I prefer to run well up into the powerband at higher speed because of the wind drag, and any little hill will be a challenge for the engine, therefore being at high RPM already will mean you don't wind up lugging the engine first, losing speed, then shifting and trying to play catch up.
Driving style A:
I've done alot of fuel mileage testing on my truck. The best fuel mileage comes from holding a steady pedal while in 6th at 60mph and about 1750rpm when pulling load weight on flat roads.
As I come to a slight hill, I don't add fuel pedal as I wait until rpm drops to 1600rpm then I down shift to 5th and return too 1750rpm and 44mph. If I'm close to topping out, I will hold 6th until I hit 1500rpm but never under 1500rpm while pulling load weight. I always drive by rpm, not speed. Speed cost money, period.
The above driving style will yield great fuel mileage while pulling 16kGCW to 26kGCW.
While at 16kGCW pulling from 2000ft to 11000ft to 2000ft (Az to Co), I can yield 14.2mpg
It also takes a light foot pedal to get the load moving. In 90% of my driving, I can up shift at 1500rpm while at 16kGCW without lugging the engine on flat roads. In any event I don't exceed 1750rpm for up shifts execpt on some grades.
Driving style B;
Holding 6th gear while traveling the same road and load weight, yielded 2mpg less with varrying my fuel pedal to add fuel while trying to stay in 6th gear. Note: This test was on the small 6%&7% grades in Az, not thru the Colorado Rockies.
Travel time increased by 15min for every 250 miles driven using driving style A
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T_Bone
02 F350, 4X6, Crew, DRW, LWB, PSD, 6spd, 3:73, Island Blue, Stock, AEB2, Phoenix Az
Buy UNION work UNION. It pays off in the long run Define Union: A labor Union is nothing more than united workers with a common goal for better working conditions.
We all are in some sort of labor Union, some are just larger than others with better working conditions!
[ QUOTE ]
On the flats or very slight grades.........
Is it better to tow at 2400 rpms with the pyro at 700 degrees and 10 pounds of boost in 5th gear? or 6th gear (O.D.) at 1900 with the pyro at 850 and boost at 5 pounds to get the best fuel economy?
[/ QUOTE ]
6th gear in a hand shaker is the same overdrive ratio as 4th in the 4R100 automagic tranny. 5th gear in a hand shaker is the same direct drive (1.00 to 1.00 ratio) as 3rd in the automagic tranny. So whether or not you use overdrive would have identical results in both a hand shaker and an automagic.
I did an experiment a few years ago, when my truck had about 44,000 miles on the clock.
Filled up with fuel (through the foam until liquid diesel was at the cap), then drug my 5er over 250 miles from Stanton across the relatively flat plains to a truckstop near Weatherford. Cruise control locked on 62 MPH all the way. Overdrive locked out. Filled up to the cap again. 8.785 MPG.
Spent the race weekend at Texas Motor Speedway near Denton, then on the way home stopped at that same truckstop in Weatherford and filled up to the cap. Then drug my 5er over 250 miles to the truckstop where I started the trip. Same truck, same 5er, same Darling Wife and puppydog in the cab. Same empty holding tanks. Cruise control locked on the same 62 MPH all the way. But overdrive used except for climbing Ranger Hill. Filled up to the cap again. 11.749 MPG.
That's a twenty five percent penalty in fuel mileage for not using overdrive on a cross-country towing jaunt.
Now folks, I've made that trip often over the last 10 years. It's slightly downhill with the wind behind me going east to Weatherford. It's slightly uphill (including Ranger Hill) going west, and usually we have a westerly headwind. So I always get better mileage going east than going west. But not that time.
So I'm going to use overdrive when I tow. And I doubt it's "hard" on the tranny. Mine had over 112,000 miles on it, mostly towing that 5er, and the stock original tranny was still going strong when I decided to have it bulletproofed. And my engine now has over 155,500 miles on it, so apparently it hasn't been hurt either.
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My Sierra Blanca is a '99.5 PSD CrewCab hot-rod Towing Machine! BTS tranny; TurboRamAir intake and 4" stainless turbo-back exhaust; DP-Tuner tunes flashed into an Edge Evolution tuner; ISSPRO EV gauges and TTM; AIC; SP-Diesel exhaust brake and torque converter controller. I special-ordered it new and plan to drive it until it quits.
I think you have an automatic, if so, the manual actually states if I recall to use overdrive like any other gear so long as it is working correctly for conditions. The problem used to be in smaller transmissions, the overdrive gears and clutches were too small to carry the load reliably.
The manuals at some point said not to tow in overdrive but I am not aware of anybody who takes that advice; with mine I am in OD by 35 mph usually. Depending on how hard I am pulling or accelerating.
With the 6.0 & manual ZF6, I drive in OD as much as possible. This puts me at 2k rpm @70 on the level w/ or w/out the trailer (6K wet). If I'm at 62 (my favorite towing speed) I'm at 1750 or so. As I get to a grade, I'll let it get to 1600, & then drop to 5th, boosting the rpms to 2.5k to hold 62. I don't have a pryo, so I can't tell you what temps are.
At 62 in OD, I can get 14.5 out of it. If I tow at 70, it drops to 11.8. I've never tried running in 5th on the flats.
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Feb 03 6.0 Silver F-250 SD SC XLT long box, 6-spd 3.73ls, Fx4, Stock, Spray-in liner, Contico box.HARPOONED.
you can always do your own test like others here and see which way you get the better milage. Most likely it will be when you're in OD. I stay in OD as much as possible with my truck. Oh and if you can, try to keep the tach at the 2k mark. For me I'm doing about 68mph then.
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2k F250 XLT CC 6sp PSD, 3.73 LS axle, Superchip, W-D Turbo Brake, Memphis speakers & 5ch amp, WD-Pyro & Boost gauges, Rechargable MagLite, quick disconnect jumper cables, CAT batteries, ARE tonneau,
"unaable" on the tailgate!! New door actuators!!
T-304 Stainless exhaust turbo back, Southbend clutch
Thanks for all the information, One thing sticks in my mind from another forum topic. Keep the pyro around 600 deg. because the engine is running most efficently. Here in dumb old Callifornia at 55 mph I can squeeze 11.5 to 12.25 on the freeeways. When in oregon I can tow at 70 mph. Milage goes down to 10 mpg. And thats at 2000 rpms. I may believe now that the low rpms are better on the flats. In the hills I think i will stay at 2400 at 60 mph on the hills. One again thanks for the response and the results of all your driving habits.
G.B.A. Support and pray for the troops
Mike C.
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2001 F350 4X4 Crewcab Lariet, 6 speed ZXG1 Code
Edge Tuner Race setting,
Pyro, Boost guages
ATS BB Turbo
4" Turbo back
AH delete
AIS intake with fender mod
Zoodad
Map Sensor pressure regulator Max 26PSI
Exhaust brake
3.5" Lift 3.73 with rear locker
33" x 16.5 Tires on weld Scorpions
Towing 27' of Trailbay trailer 8500 lb
and Hauling a DR650, DR350, XR250R
Each of these listed Axle Ratios is available for Ford Sterling 10.25 inch differentials. Those with which you are not familiar may be purchased from aftermarket vendors like Randy's Ring & Gear, which does have an online site.
In previous posts, (now mostly in the archives) I have extensively explained comparative internal friction values produced by various drivetrain configurations. I suggest that you adopt as your base-line view of F-series gearing the most efficient available transmission configuration, which is any manual transmission in its 1:1 ratio. Each of these manual transmissions, 4-speed, 5-speed & 6-speed have a 1:1 ratio which is not really a gear ratio at all because it entirely avoids loading power through ANY gears. Instead, it locks its input shaft to its output shaft. Any time you load power through a spur gear interface, assume that you just converted 1.5% of input power into waste heat while starting to use up those gear's long service lives. All overdrives require 2 gear interface steps. Any of these transmission ratios other than 1:1 load power through 2 gear interfaces, converting an extra 3% of input power to waste heat compared to these manual transmission's 1:1 non-geared ratio.
Most automatics, certainly including Ford's AOD typically convert about 15% of input power to waste heat.
I suggest that some of you to whom mapping engine efficiency as measured by horsepower-hours/gallon or horsepower-hours/pound of fuel or any of the other interconvertable standard measures is important, learn to read standard BSFC diesel maps. (BSFC = Brake Specific Fuel Consumption) That is VERY DIFFERENT from the single line ideal loading fuel consumption curve you more often see along the bottom of charts combining values for Horsepower (or Kw or other intercovertable power metrics), Torque (again, many interconvertable metrics exist), and ideal loading minimum fuel consumption, All plotted against RPMs. That single line ideal BSFC curve is a tiny sub-set of all possible BSFC map values. If more than one in 10,000 PowerStroke drivers stays on that ideal BSFC ideal line, I'd be surprised. Not only it it tough to do, but you need to manage a lot of information to attain those magically economical values.
Frankly, these boards have some very smart people posting terribly misleading and totally wrong statements about where these diesels should be loaded to minimize fuel consumption for given total road-horsepower load values. If they learn how to read those full BSFC maps, their views will change entirely and their advice will change for the better. While loading at about 80% of full throttle near a diesel's torque peak extracts most of its horsepower-hours/gallon potential, unless that power output matches well with power needed to sustain the road-horsepower load you need for your rig at the speed you most prefer, it may not be its ideal rpm for producing that power output. Also, it is entirely possible to find BSFC map positions which appear ideal but are only usable for intermittent operation because they cause over-heating problems obvious from dangerously high exhaust gas temperatures. Exploring ideal BSFC map value loading forces attention on exhaust gas temperature management techniques.
This country supports several testing labs where these issues have been explored and reported upon for decades. Some only reveal results to commercial customers who paid for that information to gain competitive market advantage. But the Nebraska State Tractor Testing Laboratory has been the US gold standard for that kind of data flow for many decades. Their reports and general advice is available to anyone with access to a public library supporting inter-library loans. Their staff has frequently summarized the total picture of results from their thousands of diesel tests of hours-long loading with precise power and fuel burn records. These tests have produced consistent results over decades of testing. Ideal loading occurs near 80% of full throttle at the lowest RPM which the tested diesel is capable of sustaining the horsepower load required by the task.
So first you need to determine your rig's sustaining load requirement at your preferred speed. That can be accomplished by coast-down time/speed recording and your rig's total scale road weight. Several systems have been sold to facilitate this for prices running from about $100 to over $500. Maybe you can borrow one or get values from an exactly the same configured rig another person has tested. Then with that required sustaining cruise horsepower requirement value in hand, go back to your diesel's BSFC map and find where it sustains that horsepower value output most frugally.
I've seen different PowerStroke powered rigs which probably require the range from about 18 road-horsepower to over 75 road-horsepower to sustain steady flat 65 mph. No one answer best fits all rigs with their variable loading. Also, anyone promoting double overdrives is promoting conversion of about 6% of input power directly into waste heat. 1:1 gearing at your most often used cruising speed is a compelling case and will result in expected manual transmission life over one million miles because the gears are not loaded even though they are spinning and interfaced whipping up the transmission lub.
John
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One measure of life success is whether you wrinkle your brain faster than you wrinkle your skin.
Lightest 1995 Standard Cab PowerStroke F-250 with factory "Camper Package," no AC, 5-speed, Conklin ParaSynthetic Oil with MolyLube, oversized 10-micron filter, Randy's Ring & Pinion aftermarket 3.07 ratio running in Royal Purple, Stanadyne always in fuel, tires @ 100 psi, nearly zero friction brake adjustments, 203 degree thermostat enables higher engine efficiency than 195 degree units, front end precisely aligned with minimal toe-in to reduce friction, lowest rolling friction F-250 I've seen. 2-axle trailer tires run 110 psi generating less rolling friction than lower pressure tires. Infrequently carried slide-in camper is an older all-hard-side Siera pop-up. Hard sides seem more secure than canvas connected pop-ups when up and never have canvas mold problems. Pop-ups push less wind than fixed height slide-ins.
able" on the tailgate!! New door actuators!!
Linear Mode
