Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 01-02-2009, 07:04 PM   #1 (permalink)
Legend in my own mind
 
trikkonceptz's Avatar
 
Join Date: Apr 2008
Location: Homestead, Fl.
Posts: 927

Evil Pumpkin - '08 Scion xD RS 1.0 #1633
90 day: 35.45 mpg (US)

Silent Silver Killer - '10 Honda Insight EX
90 day: 51.5 mpg (US)
Thanks: 2
Thanked 14 Times in 13 Posts
Diesel Gear Ratios

I had this thought from another recent post. I often borrow my brothers F-350 Diesel. It is a 2006 and has the 6.0L in it. The current gear ratio is 3.73 as it is 4x4 and has a tow package.

He does tow a heavy trailer and a swamp buggy at least once a month. He claims horrible mileage, but I know alot is driving habits, I am working on correcting that problem.

My question is; What gears can he come down to and still be able to tow near 8000 pounds? I'm sure he will benefit from a gear swap if possible.

__________________
Thx NoCO2; "The biggest FE mod you can make is to adjust the nut behind the wheel"

I am a precisional instrument of speed and aeromatics
If your knees bent in the opposite direction......what would a chair look like???





  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 01-02-2009, 07:27 PM   #2 (permalink)
EcoModding Apprentice
 
Join Date: Oct 2008
Location: los angeles, ca
Posts: 151
Thanks: 2
Thanked 19 Times in 12 Posts
He could probably drop down to 3.55s, but when you tow heavy (esp if it is up and down hills) even diesels can get pretty bad fuel economy.
__________________
1989 Dodge Diesel 972rwhp, 27mpg.
1971 Nova tubbed, solid cam 355 w/nitrous, 8mpg (sorry).
1960 Nash DIY Hybrid Project
  Reply With Quote
Old 01-02-2009, 09:43 PM   #3 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
You could easily end up with WORSE fe if geared too high. It will want to drop to a lower gear all the time.
__________________


  Reply With Quote
Old 01-02-2009, 10:22 PM   #4 (permalink)
Master EcoModder
 
Big Dave's Avatar
 
Join Date: Jan 2008
Location: Steppes of Central Indiana
Posts: 1,319

The Red Baron - '00 Ford F-350 XLT
90 day: 27.99 mpg (US)

Impala Phase Zero - '96 Chevrolet Impala SS
90 day: 21.03 mpg (US)
Thanks: 0
Thanked 186 Times in 127 Posts
I use 3.08 gears. I have no problem towing 10,000 lb trailers, sometimes through hilly country. These things have staggering torque as low as 800 RPM.

If he is a 4x4, the numerically lowest gears he can get for his front axle is 3.55 and the improvement is not worth the trouble. For 4x4s an overdrive works better. It would give you an overall 2.98:1 ratio. Overdrives are pricey, though. I could not make one make sense and I drive 25,000 miles a year.

A ratio lower than 3.55 could be trouble for an automatic transmission.

Ford now offers a 3.55 ratio as standard on diesel pickups.
__________________
2000 Ford F-350 SC 4x2 6 Speed Manual
4" Slam
3.08:1 gears and Gear Vendor Overdrive
Rubber Conveyor Belt Air Dam
  Reply With Quote
Old 01-03-2009, 08:57 AM   #5 (permalink)
Legend in my own mind
 
trikkonceptz's Avatar
 
Join Date: Apr 2008
Location: Homestead, Fl.
Posts: 927

Evil Pumpkin - '08 Scion xD RS 1.0 #1633
90 day: 35.45 mpg (US)

Silent Silver Killer - '10 Honda Insight EX
90 day: 51.5 mpg (US)
Thanks: 2
Thanked 14 Times in 13 Posts
Quote:
Originally Posted by Big Dave View Post
I use 3.08 gears. I have no problem towing 10,000 lb trailers, sometimes through hilly country. These things have staggering torque as low as 800 RPM.

If he is a 4x4, the numerically lowest gears he can get for his front axle is 3.55 and the improvement is not worth the trouble. For 4x4s an overdrive works better. It would give you an overall 2.98:1 ratio. Overdrives are pricey, though. I could not make one make sense and I drive 25,000 miles a year.

A ratio lower than 3.55 could be trouble for an automatic transmission.

Ford now offers a 3.55 ratio as standard on diesel pickups.
That is correct, they do offer a 3.55, which I may recommend he switch to. He does not however use the 4wd often and the truck does have and O/D. He and I both know MPG's tank when towing, but he wanted to improve his numbers on the street, empty. I had proven to him previously that the truck is capable of at least 22mpg, maybe now he'll change his habits. I just figured I would research all options to help him with this beast.
__________________
Thx NoCO2; "The biggest FE mod you can make is to adjust the nut behind the wheel"

I am a precisional instrument of speed and aeromatics
If your knees bent in the opposite direction......what would a chair look like???





  Reply With Quote
Old 01-08-2009, 02:46 PM   #6 (permalink)
EcoModding Lurker
 
Join Date: Nov 2008
Location: MN
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
I just yesterday sold a 97 Dodge 2500 with a Cummins diesel. When I bought it the truck had 4.10's and I couldn't get more than 17 mpg on the highway. I swapped in 3.55's in an effort to increase mpg and it really didn't make much of a difference - and may have actually hurt mpg in the city. I did get nearly 19 once - but for the cost of the swap it probably wasn't worth it in hindsight. Oh well - not my problem anymore!
  Reply With Quote
Old 01-08-2009, 03:41 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Dec 2007
Location: Central Arkansas
Posts: 33
Thanks: 0
Thanked 2 Times in 2 Posts
I would suggest the addition of a scangauge to help adjust the "nut behind the wheel". There is nothing like realtime feedback to alter behavior patterns.

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Story of a custom 5th gear for a '98 Ford Escort ZX2: +6% MPG MetroMPG EcoModding Central 14 03-05-2020 06:20 AM
Saturn S-Series 5th Gear Swap cfg83 EcoModding Central 61 05-02-2012 09:31 PM
Increasing gear ratios extragoode EcoModding Central 29 05-23-2011 03:36 PM
Met an unhappy Aveo owner today MetroMPG General Efficiency Discussion 24 10-10-2010 07:03 AM
As I Had Thought Big Dave General Efficiency Discussion 54 09-02-2008 11:00 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com