6.5 TD Highway Mileage Poll by GMC Hauler

[GMC Hauler]

Did I miss something, but what is or when are we going to see some results?

You havent. I was hoping to get 20 responses before I put something out. I have most of the data computed. I'll give it another week. If I cant get the desired responses, i'll put out some info.

In the meanwhile, everyone that hasn't posted, please post.

[fastcat800]

--------------------------------------------------------------------------------

1. What model do you drive Truck Shortbed, Truck Extended Cab, Suburban, Tahoe, Other (Specify): 1994 pickup shortbed extended cab empty load
2. Level 1500
3. 4x4
4. Driving Habits; 2
5. Tune of vehicle; 3
6. Fuel additive added every fillup in OZ; PS 4 oz's
7. Size of fuel tank 25 Gal.
8. Rear Gear Size (3.23, 3.55, 4.10, ect):3.73
9. Tire Size (ex; 245/75 R16): 245/75 R16
10. Tread style; Mud/Snow
11. Gear vendor? (if so, od/ud ratio and how you use it): None
12. Boost control; Mechanical/Electrical: Factory
13. Boost pressure setting (4-20lbs): factory
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): Factory
17. Timing Gear Y/N: STOCK
18. Intercoooled Y/N: STOCK
19. Mist injection Y/N: STOCK
20. Air filter (stock, stock w/ airbox mods, stock airbox with special filter, both, 97 and newer box, cone filter): STOCK AIRBOX with hole cut in the top of the box.
21. EGR/Non EGR: Non EGR 1 ton intake manifold
22. GM Turbo Style (GM5,6,8, other): 1994 STOCK
23. Exhaust (Stock, mufff removed, kitty removed, 3", 3.5", 4", other) STOCK
24. TDC offset set to (stock, or the value you have it set to):STOCK? don't know, rattles really loud at idle
25. Stock injectors/High pop: STOCK
26. Synthetic oil Y/N: YES, Rotella 5W-40
27. Highway mileage (not towing, best averaged over 3 tanks): 19.5MPG @ 75MPH, 21.2MPG @ 65MPH, 16.5MPG average city
28. When mileage data was obtained (Winter, Summer): Summer/ Winter is aprox. 2MPG less in all above conditions
29. Approx miles on vehicle:200K

[john8662]

mite as well contribute rite?

1. Suburban:
2. 2500
3. 4x4
4. 2
5. 2
6. none
7. 42 gal
8. 4.10
9. 245/75 R16
10. Highway
11. No
12. factory
13. factory 9psi observed.
14. Automatic Trans
15. 180 Dual
16. Stock F
17. No
18. No
19. No
20. 97 a/b Purolator Paper
21. Vin F, non-egr
22. GM-4
23. 4"
24. stock - .7
25. stock pop injectors
26. No, Delo 15w40
27. 16 mpg
28. Winter
29. 100k

[V8 Power]

1. Truck long bed extended cab
2. 2500
3. 4x4
4. 3
5. 4
6. none
7. 34 gal
8. 4.10
9. 245/75/16
10. Mud/Snow
11. no
12. factory
13. factory (I think 9 psi)
14. manual
15. none
16. stock
17. stock
18. no
19. no
20. Factory
21. non
22. stock
23. 4"
24. stock
25. stock
26. no
27. 16
28. summer
29. 243000 (43000 after overhaul)

[ogrice]

Please post your results and how you came about to calculate everything. Here is my rig's info.

1- pickup, regular cab, long bed
2- 3500 dual rear wheel
3- 2x4
4- 2
5- 1
6- 12 oz of diesel kleen or lucas oil
7- 36 gallons
8- 3.73
9- 235/85 R16
10- Highway
11- not installed
12- mechanical boost control
13- 0-10lbs. 12lbs max
14- manual trans nv4500
15- 195 degrees
16- no pcm. DB2 pump
17- yes
18- no, in the works though
19- no
20- K&N round element
21- non EGR
22- GM-3
23- BD 4"
24- stock I guess. don't know with DB2 pump
25- hi pop.
26- no
27- 20.8 highest avg.
28- summer
29- truck has 234k. engine has 34k.

I use propane on the highway. MPG figures are with propane use.

[GMC Hauler]

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.






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.

[moondoggie]

Good Day!

Any chance of getting this in spreadsheet form? If so, you could private message me your real email address, & I'd give you my real email address, to which you could attach this spreadsheet to an email.

Looks like that moondoggie feller is near the top. Did he tell you he's a pathological liar?

Blessings!

(signature in previous post)

[GMC Hauler]

Good Day!

Any chance of getting this in spreadsheet form? If so, you could private message me your real email address, & I'd give you my real email address, to which you could attach this spreadsheet to an email.

Looks like that moondoggie feller is near the top. Did he tell you he's a pathological liar?

Blessings!

(signature in previous post)

You've got mail.

Everyone can get it in spreadsheet form if they wish, just PM me your email address.

I can continue to add data. I'll do it in batches of 5 as it is entered.

The next update I make wil have an overall gear ratio instead of the tire size and rear end ratio.
Alot more accurate that way.

[RT]

1. What model: 1993 Chevrolet Silverado long bed, extra cab.
2. Level 2500HD (eight lug hubs)
3. 2x4:
4. Driving Habits; 2
5. Tune of vehicle; 3
6. Fuel additive added every fillup in OZ; 6oz Stanadyne or Howes + 2cycle oil
7. Size of fuel tank: 34gallon
8. Rear Gear Size: 3.42
9. Tire Size:245/75 R16
10. Tread style; Mud/Snow
11. Gear vendor?: No
12. Boost control; Mechanical-Heath
13. Boost pressure setting: 11psi
14. Manual/Automatic Trans: Manual, 5spd
15. Thermostat: 180*F
16. PCM programming: No computer!
17. Timing Gear Y/N: DSG geardrive
18. Intercoooled Y/N: No
19. Mist injection Y/N: No
20. Air filter: SS Diesel Supply K&N style
21. EGR/Non EGR: No EGR
22. GM Turbo Style: GM-8
23. Exhaust: BD 4" with 3" downpipe
24. TDC offset set to: NA
25. Stock injectors/High pop: Stock
26. Synthetic oil Y/N: Yes
27. Highway mileage (not towing, best averaged over 3 tanks): 19.2mpg
28. When mileage data was obtained (Winter, Summer): Summer
29. Approx miles on vehicle: 241,000

RT

[HiwayDiesel]

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....

[ace58]

I had to post results. It works. I have never driven consistent enough to record numbers any better than 17 MPG but today I went on a 278.2 mile ride on 13 gallons of fuel and got 21.4 MPG. Stayed at 1800 RPM which is 65 MPH with 3:42 rear gear.

1. 1999 Suburban LT
2. 1500
3. 4X4
4. 1 on this ride
5. tune is #1
6. Kennedy mix of cetane and lubricity
7. 42 gallon
8. 3:42
9. 245/75/16
10. mud/snow
11. none
12. Peninsular non waste-gate
13. "
14. automatic
15. 195
16. Heath Computer
17. timing chain set
18. Kennedy Intercooler
19. no mist
20. Kennedy Air Box
21. no EGR
22. Peninsular non waste-gate
23. Kennedy 3.5 system, coated cross over and coated manifolds
24. -1.94
25. high pop
26. Amsoil 15/40
27. 21.4
28. 164K truck 2500 Peninsular 18.1 engine

[d.h.]

1. c/c l/b
2. 3500 dually
3. 4x4
4. 4
5. 1.5
6. Shaffers one capfull every fill
7. 35 Gall
8. 4:10
9. 225/75 16
10. Highway
11. No
12. Boost fooler (elec)
13. 15lbs(pulling)
14. Automatic
17. No
18. Yes
19. No
20. Aftermarket
21. egr
22. GM-8
23. 4"straight
24. Stock
25. High pop
26. Yes
27. 18 empty
28. summer
29. 200,000 km

[ECMProgrammer]

1. Truck Extended Cab SWB
2. 2500
3. 4x4
4. 3-4
5. 1
6. none
7. Stock
8. 4.10
9. 265/75R16
10. Mud/Snow, Highway:
12.None
13. 6-7 cruise, 18 WOT
14. Automatic Trans:
15. Stock
16. Westers
17. Stock
18. Stock
19. N
20. Stock
21. Non EGR:
22. Stock
23. mufff removed, kitty removed, 3"
24. -1.24
25. Stock injectors
26. Castrol 5W50 Synthetic
27. 24-26
28. Summer
29. 378,000 kms

Lyndon
www.ecmprogrammer.com
Westers Garage

'98 6.5TD VIN "F", '01 C5 Convertible, '04 LLY, '05 SSR, '05 Yukon

[AndyL]

1. 1980 Olds Cutlass
2. 1/8 Ton
3. RWD
4. Driving Habits; 2
5. Tune of vehicle; 3
6. Fuel additive added every fillup in OZ; 2-Cycle Oil
7. Size of fuel tank (Suburban is 42 gal): 18 Gallons
8. Rear Gear Size (3.23, 3.55, 4.10, ect): 3.30
9. Tire Size (ex; 245/75 R16): 255/60R15
10. Tread style; Offroad, Mud/Snow, Highway: Highway
11. Gear vendor? (if so, od/ud ratio and how you use it): None
12. Boost control; Mechanical/Electrical: NA
13. Boost pressure setting (4-20lbs):
14. Manual/Automatic Trans: 700R4
15. Thermostat (160, 180, 190, 195, 205, 215, none): 180
16. PCM programming (Heath 1.0, 2.0, Kennedy 72/76/max, Westers): Kennedy DB2
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): Factory
21. EGR/Non EGR: EGR Blocked
22. GM Turbo Style (GM5,6,8, other):
23. Exhaust (Stock, mufff removed, kitty removed, 3", 3.5", 4", other) Dual 2.25" straight pipes
24. TDC offset set to (stock, or the value you have it set to): By ear
25. Stock injectors/High pop: New stock
26. Synthetic oil Y/N: 5w-40 Rotella
27. Highway mileage (not towing, best averaged over 3 tanks): 30.1 Best, 27-29 Average
28. When mileage data was obtained (Winter, Summer):
29. Approx miles on vehicle: A zillion! Needs timing chain BAD!