less than 12 MPG
12-13 MPG
14-15 MPG
16-17 MPG
18-19 MPG
20-21 MPG
better than 21 MPG
Just looking
Newbie
Well,
It is a express 3500 van with 5,500 pounds in weight, not necessarily the same category as a Crovette. However, I am not out to win acceleration contests but get good fuel mileage. Would the tranny suffer from such gearing? I am just trying to find out if the higher gearing to 3.43, such as 3.03, would be doable with a compromise in acceleration of it is just not practicable. Was wondering to mayby do 3.43 and experiment around with larger diameter tires...
Last edited by Captain Jojo; 01-31-2011 at 14:28.
2001 Chevy Van 3500 Express, no changes to factory, 6.5TD, 82k miles, USAF van until 77k. 4L80 tranny, 3.73 rear gearing, PMD relcated underneath the bumper.
Proud Deplorable
Pick a speed, say 65 mph. Now, pick a gear ratio and tire size that puts you between 1800 and 2000 RPM. I think you'll find that 3.42 is going to be close to optimal unless you are grossing 10K or more. 3.03 is going to put you below the most efficient range, lugging if you will.
The Constitution needs to be re-read, not re-written!
If you can't handle Dr. Seuss, how will you handle real life?
Current oil burners: MB GLK250 BlueTEC, John Deere X758
New ride: MB GLS450 - most stately
Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510
Newbie
Hey JohnC,
Am reading and learning. Thanks for your patience, am somewhat only getting started really getting to know cars and diesels in particular.
3.03 is going to put the engine below its torque peak, understood. I guess my question is still: what rpm would I land up with and how sluggish would that be? Still drivable in everyday driving conditions but just a bit slower acceleration, or almost no acceleration at 65? The fuel economy should be better below torque peak at 65, wouldn't it?
I assume you are saying that the gains in MPG would be too small to justify the compromise in acceleration? Or do I loose mpg because the overdrive wouldn't lock?
Thanks a bunch for your help, I appreciate it.
J
2001 Chevy Van 3500 Express, no changes to factory, 6.5TD, 82k miles, USAF van until 77k. 4L80 tranny, 3.73 rear gearing, PMD relcated underneath the bumper.
Building another 6.2L powered vehicle
My 99 Suburban, 4.10 gears, 115K with marine injectors.
Was getting 15 mpg with 245/75R16's.
Now getting 18 mpg with 285/75R16's. They just barely fit, but it sits nice and the BFG A/T rubber looks mean.
Both fuel mileage indications taken from my regular commute. 13 miles one way, till I hit 1/4 tank. 42 gallon tank. 55 mph speed limit, with the cruise set to 57-58 per GPS since the speedo is now off. 2K RPMS for 55 sucked with the little tires.
05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
72 Postal Jeep - Yet another project
Gran Turismologist
1 year update on the fuel economy for my Suburban: This is an aggregate average of a full year's worth of driving and fuel use. Since the conversion was completed, it has traveled 18,485 miles, consumed 740.258 Gallons of fuel, and averaged 24.971 MPG. This is overall MPG, with around town and highway. Best tank 28.1 MPG. Worst tank 17.7 MPG. I am very satisfied.
1993 Suburban 2wd 6.2L Diesel Conversion "Andromeda":
3.73:1 gears, THM 700-R4 transmission, and
J-code 6.2L diesel from a 1984 C2500 Suburban
1996 2wd to 4wd converted Ford F-150 300ci Inline 6 "The Argo" 336,000 miles and climbing
1992 Caprice Wagon 5.0L V8 "Enterprise-D"
"Ah ha ha ha! I swear! Tractors is so dumb!" - Mater
"The Argo? That ridiculous pile of scrap metal!"
Posting Permissions
Reply With Quote