Re: mpg difference with od upgrade
[Re: GoodysGotaCuda]
#1781463
03/16/15 10:37 PM
03/16/15 10:37 PM
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Joined: Aug 2005
Posts: 6,018 Salem
Grizzly
Moparts Proctologist
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Moparts Proctologist
Joined: Aug 2005
Posts: 6,018
Salem
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It's not just what you save on fuel, you will see a return on your overdrive investment when, or if you decide to sell your car. As long as there is no cutting involved, you should be able to recover a good $1000.00 back. I would take a nicely done automatic overdrive conversion over a 3 speed auto dinosaur any day.
Mo' Farts
Moderated by "tbagger".
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Re: mpg difference with od upgrade
[Re: WO23Coronet]
#1781465
03/17/15 12:51 AM
03/17/15 12:51 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
Does anybody have real #'s for the performance difference a 46RH will cost over a 727? How much extra HP does it use?
Once upon a time I searched high and low for this but could find nobody reporting a real world first hand experience of a gain or loss at the drag strip when changing to or from a 518 or 500. Just a lot of here say and old wibes tales.
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Re: mpg difference with od upgrade
[Re: dOc …]
#1781468
03/17/15 03:01 PM
03/17/15 03:01 PM
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Joined: Jan 2005
Posts: 12,424 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,424
Kalispell Mt.
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I have done a bunch of those swaps and see typically 2-3 mpg. I have never seen a car lose MPG going to a higher final drive. I plan to do an experiment in my dakota at some time and really push the limit as in 2.45 gears AND OD for a final drive of 1.69.
Your math will vary depending on if you are buying a trans either way, you can get a 727 with a few mild upgrades for about $750 and a 518 for about $1200 so only about $450 difference (my prices, shops in your area will vary in price and quality). If you are making a drive shaft for something than the 518 shaft will be slightly shorter and should be a couple bucks cheaper and a shorter shaft don't mind the RPM as much. The only performance difference is a a little friction from the extra clutches that are not engaged, a few pounds of rotating mass and a couple pounds of non-rotating, probably no more than 1 or 2 tenths, couple in the fact you can run a little lower gear and there should be no real performance difference. Also if you are doing the work than you may or may not have some extra time into it, if you are paying someone to do it you may have some extra dollars into that.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: mpg difference with od upgrade
[Re: Hrtbkr]
#1781469
03/17/15 03:18 PM
03/17/15 03:18 PM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
The other factor is you save a lot of wear on your engine when you install an OD. I had lots of trouble sorting mine, but now I'm glad I have one.
True in theory. But in reality how many miles do most old mopars see in a year? A few thousand at most? And how muc h of that is slow cruising in town instead of highway driving? You would probably have to drive that old car 30 years to see any measurable difference in wear.
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Re: mpg difference with od upgrade
[Re: HotRodDave]
#1781470
03/17/15 03:37 PM
03/17/15 03:37 PM
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Joined: Jun 2008
Posts: 10,847 Oakdale CT
gdonovan
I Live Here
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I Live Here
Joined: Jun 2008
Posts: 10,847
Oakdale CT
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I upgraded my Duster to a 44RH and it cost me about $800-$900 including the cost of the core. Rebuilt the unit, upgraded some parts and purchased a MP lockup converter.
MPG gains were not outstanding (I do have a heavy foot) BUT I'm now able to pass everything on the highway without pounding the motor to death and the cabin noise is greatly reduced.
Highway cruise is now 2100 vs 3500 RPM
"I think its got a hemi"
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Re: mpg difference with od upgrade
[Re: Skid_Demon]
#1781475
03/18/15 10:12 PM
03/18/15 10:12 PM
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Joined: Apr 2012
Posts: 77 South East Ontario, Canada
Ramtough
member
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member
Joined: Apr 2012
Posts: 77
South East Ontario, Canada
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A lot of variables, what gear are you running, tire size, average cruise speed. Most engines that we deal with are built and cammed to pull on the road at 2000 rpm or better, get them below that and you are labouring it all the time eating more fuel. I am putting a O/D in my 77 short box truck with 3.91 gears and 28" tire, most of my driving at 55-60 mph so it should fine. My daily drive is a 92 W150 - 318, the O/D and lock-up quit working early Dec., my fuel mileage went from avg. of 12 to 13.5, turns out it better with out, not going to fix.
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