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  #1  
Old 07-02-2002, 09:05 PM
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Checkmate Checkmate is offline
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Default Hey diesel heads...

I am looking into getting a new truck within the next 6 months. The question I have for you guys is this. I will probably be running 40+" tires, will a diesel get me better mpg than a gas engine ?? I am assuming so because of the torque, but then again I have never owned a diesel. What other positives are there to the diesel besides reliability? Thanks for any info, Checkmate
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Old 07-02-2002, 10:29 PM
blackcuda blackcuda is offline
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SAY WHAT

I belive you will be VERY pleased with the fuel milage of the cummins. I have a 95 cummins 3500 w/ 4.10 gears and a 5 speed. I reg. get 20.5 mpg and have done as good as 22 mpg no trailer/ load, and when pulling my car I get 16.5 to 18 mpg.

I think you can't go wrong with the diesel, just don't ingest a bunch of water while havin fun or you'll have problems...
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Old 07-03-2002, 09:02 AM
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My advice is to get the cummins with 4.1 gears if running tires that tall. I'd also get the manual trans and put a good clutch in it.
The ho - 6 speed is the first choice. you will be impressed with the power and mileage. These modern diesels can run hard. Trust me!
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  #4  
Old 07-05-2002, 09:20 PM
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Default Re: SAY WHAT

Quote:
Originally posted by blackcuda
I belive you will be VERY pleased with the fuel milage of the cummins. I have a 95 cummins 3500 w/ 4.10 gears and a 5 speed. I reg. get 20.5 mpg and have done as good as 22 mpg no trailer/ load, and when pulling my car I get 16.5 to 18 mpg.

What size tires do you have with that mileage ??
Thanks for the replies guys.
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  #5  
Old 07-05-2002, 10:41 PM
blackcuda blackcuda is offline
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Post Tires

My truck is a two wheel drive and I am running LT 235 85 16 on it. I would have to agree if you are going to run that big a tire then the 4.10 would be a good gear for you. I wish I had a 3.54 for my lil tire truck
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Old 07-06-2002, 02:40 PM
Duffys Ramcharger Duffys Ramcharger is offline
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I think you will need gears lower than 4.10 for 40" tires. More like 4.88 or 5.13. Don't forget that they have an overdrive gear in the trans. You can only get the 3.5 or 4.1 gears factory, so you would have to put the gears in your self. The formula for figuring out the driveshaft RPM is this
gear ratio x speed x 336 / tire diameter
example
4.10 gears x 65 mph x 336 / 31"(245 75 16 tires) = 2889 driveshaft rpm
Thats in drive.
2889 x .75 for standard(.69 for auto) to figure out engine rpm in OD.
2167 for standard 1993 for auto.
Use this formula to figure out what gears will work best for your application and tire size.
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Old 07-07-2002, 12:33 AM
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See, that's just it, I know that you can't swap gears like a gas engine. What I mean is the rpm range for the power band and redline. If I had a 60 in my truck now I would have gone 4.88's with my 35's or 38's. So with a gas engine and 40's or bigger I would be tempted to go 5.13's, but would that keep the diesel out of the high rpm's ?? Or would I want to keep it at 4.88's ?? My buddy has a Chevy with 44's on it. He has an Olds 455 under the hood and runs 4.56 gears !!! I told him he was crazy not to go with 4.88 AT LEAST. He says, no it's a toque motor. He says he is happy with his choice, however it sounds like a dog when he gets on it from a light.
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  #8  
Old 07-07-2002, 03:54 AM
Duffys Ramcharger Duffys Ramcharger is offline
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Wink

I found this site
http://www.superlift.com/gear.htm
As you can see, you would have to use 5.29 gears to keep the same rpm's with 40"s as with stock 31"(245/75R16).
I also found this site.
http://www.4wheelparts.com/Tirel_gear_ratio.asptires.
My dad has a 97 4x4 diesel 5 speed with 285/75R16 (33") tires and 3.55 gears, and it runs realy good at 75 mph
It depends on if you want it for freeway or tourq and towing.
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  #9  
Old 07-09-2002, 02:48 PM
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I am looking hard into getting a 2003 2500 Diesel. They are putting out more torque and hp than any other year. I think this is my best choice, if I can afford it.
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