Standard/Automatic- MPG
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Cargo Master
Joined: Sep 2005
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Standard/Automatic- MPG
In my quest for a better MPG work truck I'm building a 74 F-350 , at this point I can do anything I want for a drivetrain. What I need is a couple of people with identical trucks but 1 auto and 1 standard that know what they are getting for mileage. Preferably someone who drives moderatly. My present setup is 390 4v with c-6 and 3.55 rears. I don't thinkit will matter what the 2 test vehicles are I'm just looking for the difference in mileage as a percentage.
By the way sofar I am ecstatic with the new truck without even tuning it up yet and the tranny slipping a bit it got 10 mpg on the second tank. that's already a 2 mpg jump from my present work truck. That has already knocked $100 a month off my Gas bill.
By the way sofar I am ecstatic with the new truck without even tuning it up yet and the tranny slipping a bit it got 10 mpg on the second tank. that's already a 2 mpg jump from my present work truck. That has already knocked $100 a month off my Gas bill.
Elder User
Joined: Apr 2004
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From: Tucson, AZ
I have a '73 and '78 F100s both with sixes. '73 has a C4 and the '78 has a 3.03 3 speed. The '78 seems to get a little better mileage, not real signicant but this might be because the engine is in a little better shape and not cause of the manual tranny. I would stay with automatic, if anything get an overdrive automatic like a built AOD. Manuals usually last longer but it can sure get tiresome shifting especially with these old mechanical clutches.
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Cargo Master
Joined: Sep 2005
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Originally Posted by fordflaresides
I have a '73 and '78 F100s both with sixes. '73 has a C4 and the '78 has a 3.03 3 speed. The '78 seems to get a little better mileage, not real signicant but this might be because the engine is in a little better shape and not cause of the manual tranny. I would stay with automatic, if anything get an overdrive automatic like a built AOD. Manuals usually last longer but it can sure get tiresome shifting especially with these old mechanical clutches.
Oh and Million, nice post, but it really isn't related to my question. I intend to do everything I can to increase the mileage, this is just one step.
Lead Driver
Joined: Nov 2000
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From: Albuquerque
Given the same rear end ratio the standard is capable of higher mileage if driven easily because the torque converter has some slippage and a C-6 takes a lot of HP to turn. Auto's usually have a slightly lower (numerical) gear ration to compensate for this.
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Cargo Master
Joined: Sep 2005
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Originally Posted by beartracks
Given the same rear end ratio the standard is capable of higher mileage if driven easily because the torque converter has some slippage and a C-6 takes a lot of HP to turn. Auto's usually have a slightly lower (numerical) gear ration to compensate for this.
Postmaster
Joined: Nov 2003
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From: Cab of a truck
Ive been told and I read on here that there is a difference of 60rrhp between the C6 and the NP435 4spd manual, the 4psd having more. Id assume mileage increase would be in the 1-4 mpg range.
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Post Fiend
Joined: Mar 2005
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From: Louisiana
I've seen guys run 390s with autos an standards, and with either one they don't see much over 10 MPG. The cost of overhauling a C6 isn't cheap, and you could get a NP435 out of a junk yard, put new seals and everything like that, install it, and still probabaly come out cheaper than overhualing the C6 and maybe getting 1 (or 2 at best) mpgs better.
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Oh and Million, nice post, but it really isn't related to my question. I intend to do everything I can to increase the mileage, this is just one step.
Reply With Quote
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Thanks...My point is:there are so many things that alter fuel economy even a little bit that it is very difficult to be specific about what it will be or be changed to.
Reply With Quote
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Thanks...My point is:there are so many things that alter fuel economy even a little bit that it is very difficult to be specific about what it will be or be changed to.
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Cargo Master
Joined: Sep 2005
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Originally Posted by Mil1ion
Oh and Million, nice post, but it really isn't related to my question. I intend to do everything I can to increase the mileage, this is just one step.
Reply With Quote
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Thanks...My point is:there are so many things that alter fuel economy even a little bit that it is very difficult to be specific about what it will be or be changed to.
Reply With Quote
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thanks...My point is:there are so many things that alter fuel economy even a little bit that it is very difficult to be specific about what it will be or be changed to.
Elder User
Joined: Feb 2002
Posts: 987
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From: East Bend, Carolina, U.S
Don't forget to ask about the terrain when you get a reply. Not even semi accurate mpg comparisons can be made for hills vs flatland.
You probably aren't going to get a perfect comparison for this, but it will be at least more accurate than less accurate when similar terrain is observed.
You probably aren't going to get a perfect comparison for this, but it will be at least more accurate than less accurate when similar terrain is observed.
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Cargo Master
Joined: Sep 2005
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Originally Posted by Mil1ion
This is a perfect case for the 2v vs 4v for fuel economy then.
Without the back 2 bbls kicking in,the 4v should get better mileage
Without the back 2 bbls kicking in,the 4v should get better mileage
. The other thing I've been contemplating is a hydraulic drive axle for the front. There isn't too many times I need 4wd, but it does happen. And I'll have the hydraulic system for a dump bed anyway. And I could build the entire unit without disabling the truck, then just swap it in. that would probably be the last project.
Post Fiend
Joined: Jul 2003
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From: Spokane, WA
Originally Posted by FordPickup460
Id assume mileage increase would be in the 1-4 mpg range.