6.5 TD Highway Mileage Poll by GMC Hauler
Ok. I finally got the information together, and here it is. Please respond in number to each question. If you have any notes or deviations from the included options that you believe are signifigant, please make a note. If you want to ask questions before posting, send me a PM.
1. What model do you drive Truck Shortbed, Truck Extended Cab, Suburban, Tahoe, Other (Specify):
2. Level 1500, 2500, 3500, 3500 dual rear wheels:
3. 4x4 or 2x4:
4. Driving Habits; 1 to 5 with 1 being conserative and 5 being a lead foot:
5. Tune of vehicle; 1 to 5 with 1 being perfect, 3 being average, and 5 as poor:
6. Fuel additive added every fillup in OZ; number or none:
7. Size of fuel tank (Suburban is 42 gal):
8. Rear Gear Size (3.23, 3.55, 4.10, ect):
9. Tire Size (ex; 245/75 R16):
10. Tread style; Offroad, Mud/Snow, Highway:
11. Gear vendor? (if so, od/ud ratio and how you use it):
12. Boost control; Mechanical/Electrical:
13. Boost pressure setting (4-20lbs):
14. Manual/Automatic Trans:
15. Thermostat (160, 180, 190, 195, 205, 215, none):
16. PCM programming (Heath 1.0, 2.0, Kennedy 72/76/max, Westers):
17. Timing Gear Y/N:
18. Intercoooled Y/N:
19. Mist injection Y/N:
20. Air filter (stock, stock w/ airbox mods, stock airbox with special filter, both, 97 and newer box, cone filter):
21. EGR/Non EGR:
22. GM Turbo Style (GM5,6,8, other):
23. Exhaust (Stock, mufff removed, kitty removed, 3", 3.5", 4", other)
24. TDC offset set to (stock, or the value you have it set to):
25. Stock injectors/High pop:
26. Synthetic oil Y/N:
27. Highway mileage (not towing, best averaged over 3 tanks):
28. When mileage data was obtained (Winter, Summer):
29. Approx miles on vehicle:
This is the items I could come up with that should affect mileage. I will store this data, and use graphs and a table to organize the data. If you have items on your rig that arent used in your calculation for mileage then make a note or don't include them (such as mist injection). I will report after we get enough data to start showing a trend.
I bet I get the lowest MPG
1. 1999 Suburban
2. 2500
3. 4x4
4. Driving Habits: 2
5. Tune of vehicle: 1
6. Powerservice 8oz
7. 42 Gallons
8. 3.73
9. 265/75-16
10. BFG A/T
11. Gear vendor? No
12. Mechanical Turbo-Master
13. 15lbs max when towing up mountain passes
14. Auto trans
15. Factory Original t-stats
16. Heath 2.0
17. Timing Gear Y/N: No
18. Intercoooled Y/N: No
19. Mist injection Y/N: No
20. Stock airbox w/ AFE filter
21. Non EGR
22. Factory Original Turbo
23. 3" mandrel all the way, cat's still there for now.
24. TDC offset set to: -1.94
25. Factory Original injectors
26. Synthetic oil Y/N: No
27. Highway mileage @ 65-70mph (and speedo is accurate): 16mpg
28. When mileage data was obtained (Winter, Summer): Combined
29. Approx miles on vehicle: 66000
Guess I should answer my own poll...
1. What model do you drive: Suburban
2. Level :2500
3. 4x4 or 2x4: 4x4
4. Driving Habits; 1 to 5 with 1 being conserative and 5 being a lead foot:3
5. Tune of vehicle; 1 to 5 with 1 being perfect, 3 being average, and 5 as poor: 2
6. Fuel additive added every fillup in OZ; number or none:16
7. Size of fuel tank (Suburban is 42 gal):42
8. Rear Gear Size (3.23, 3.55, 4.10, ect):4:10
9. Tire Size (ex; 245/75 R16):235/85 R16E
10. Tread style; Offroad, Mud/Snow, Highway:highway
11. Gear vendor? (if so, od/ud ratio and how you use it):no
12. Boost control; Mechanical/Electrical:mechanical
13. Boost pressure setting (4-20lbs):12
14. Manual/Automatic Trans:auto
15. Thermostat (160, 180, 190, 195, 205, 215, none):195
16. PCM programming (Heath 1.0, 2.0, Kennedy 72/76/max, Westers):Heath 2.0
17. Timing Gear Y/N:n
18. Intercoooled Y/N:n but i need one bad.
19. Mist injection Y/N:n
20. Air filter (stock, stock w/ airbox mods, stock airbox with special filter, both, 97 and newer box, cone filter):stock with airbox mods, unifilter
21. EGR/Non EGR:non egr
22. GM Turbo Style (GM5,6,8, other):5
23. Exhaust (Stock, mufff removed, kitty removed, 3", 3.5", 4", other):4", no kitty
24. TDC offset set to (stock, or the value you have it set to):-1.47
25. Stock injectors/High pop:stock
26. Synthetic oil Y/N:next oil change goes in the Amsoil
27. Highway mileage (not towing, best averaged over 3 tanks):15.207
28. When mileage data was obtained (Winter, Summer): summer
29. Approx miles on vehicle:124K
Once i reach 20 responses, i'll put out some data.
Thanks for taking the time to asnwer:D
The data crunching is complete.
I have finished putting together the data. I had to fit the data as best as possible. I assumed 195 is the stock
thermostat setting (if it is different, please advise). Also, Ogrice, I did not use yours becasue of the propane use,
it would introduce too many variables.
http://pic14.picturetrail.com/VOL514.../162046734.jpg
http://pic14.picturetrail.com/VOL514.../162046732.jpg
As you can see, i had to break it up into 2 sections, because it was too long.
This is sorted top to bottom from highest mileage to lowest. Most of the lower gear ratios (3.23) were concetrated near the top.
The 4.10's were sprinkled throughout, which was surprising.
The other trend I noticed is that the higher mileagers were electronic boost control, where the lower mileagers were dominated by mechanical.
I have been thinking of switching back to electronic boost control for this reason, although I don't want to use the factory vacuum pump.
310 Chassis, TYMCO Sweepers (4)
1. 310 Cab/Chassis (135.5" Chassis) with TYMCO Sweepers 96-98-99-00
2. 3500 DRW
3. 2x4
4. Employees (4.5)
5. Runs (3)
6. Nada
7. 20?
8. 410
9. 235/85-16
10. M/S
11. None
12.Stock
13.4
14. Auto 4L-80E
15. 195
16. N0
17. N0
18. N0
19. N0
20. Stock
21. EGR
22. Stock
23. Stock
24. Stock
25. Stock
26. No, Rotella
27. Only have fleet avg mileage: 8.67
28. Last fleet report (Oct 06)
29. Approx miles on vehicle: 245,000, 230,000, 195,000, 183,000
These trucks get the worst abuse you can dish out. Low speed parking lots, then high speed runs. Operators understand: start, drive, stop. The whole "how diesels work" escapes them. Repairing a broken frame today....weeee....