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Re: Upgrades for fuel economy [Re: 1953 panel] #1268744
Mon Jun 11 2018 01:53 PM
Mon Jun 11 2018 01:53 PM
M
moparguy  Offline
Shop Shark
Joined: Sep 2013
Posts: 617
Watford City ND...
Originally Posted by 1953 panel


I had someone tell me that driving with the tailgate down would also gain 1 or 2 mpg.



Not sure on that one. It "could" be the case on our older trucks, but I've seen several smoke streams from the labs studying air flow in a wind tunnel and modern trucks lose mileage with the tailgate down or off. It messes up the factory aerodynamics bigtime. On a personal note, my wife's truck when new (2015 Ram 2500 4x4) got a dependable 17 to 19 mpg. When it was about three weeks old we pulled the bed and installed a new CM flat bed. No tailgate obviously and a small bit, around 2" or 3 of headrack and flatbed extending past the cab. With the flatbed induced airstream disruption, mileage dropped 2 mpg and now runs 15 to 17mpg on a good trip when not pulling a trailer.

I think coilover was on the right track in his chasing 20mpg with a straight 8. Now I'm just dreaming here and odds are likely never will, But if I wanted to build a mileage champ AD truck, I'd go diesel. Not Cummins, though I'm a Cummins fan but a Isuzu 4BD1TE. Thisdetails a Isuzu conversion on a Toyota Landcruiser that was seeing 26mpg. Not Stovebolt but interesting for sure.

All the above said, mid teens ain't bad for our rigs. I've got better on long drives but fact is these trucks aren't about modern mpg. For me it's more about spm (smiles per mile) than mpg.

Last edited by moparguy; Mon Jun 11 2018 01:55 PM.

1951 3600 with Clark flatbed, T5, 4.10 rear
1970 340 Duster
1990 5.0 V8 Miata (1990 Mustang Gt Drivetrain)
1951 Farmall Super A



Re: Upgrades for fuel economy [Re: Stooby] #1268748
Mon Jun 11 2018 02:03 PM
Mon Jun 11 2018 02:03 PM
P
panic  Offline
Shop Shark
Joined: Dec 2008
Posts: 1,145
Long Island
I had someone tell me that driving with the tailgate down would also gain 1 or 2 mpg.
Mythbusters did this, and in their test it hurt: http://www.discovery.com/tv-shows/m...abase/driving-tailgate-fuel-consumption/

Re: Upgrades for fuel economy [Re: Stooby] #1268755
Mon Jun 11 2018 03:08 PM
Mon Jun 11 2018 03:08 PM
C
carbking  Offline
Carburetion specialist
Joined: Nov 2002
Posts: 1,737
Missouri
All tests that I have seen dropping the tailgate hurt the mileage.

On the other hand, a cab-high aluminum bed topper seems to help the mileage.

Personally, the two largest gains I made on my own 1968:

(1) Switch from a dogmatic to a 4-speed (24 percent)
(2) Removal of the "bug screen along the front of the hood (12 percent)

Jon


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: Upgrades for fuel economy [Re: Stooby] #1268997
Wed Jun 13 2018 06:11 PM
Wed Jun 13 2018 06:11 PM
J
jfnar  Offline
Shop Shark
Joined: Aug 2006
Posts: 469
Arkansas
Carbking, I'd be interested in the details on your 68. I'm also working on a 68 gmc. My first mileage check was 15.25 but I found that the choke was not opening completely so I'm hoping to do better on the next tank. I have a 292 with 390 holly 4 bbl and HEI. All the internals of the engine are stock. I have an A833 OD transmission and 3.73 rear gears. It runs about 2000 rpms at 60 mph.


'64 swb stepside (gone)
'57 1 ton
'53 phone truck
'59 swb
'46 1 1/2 ton
'68 swb gmc
Re: Upgrades for fuel economy [Re: jfnar] #1269049
Thu Jun 14 2018 01:28 PM
Thu Jun 14 2018 01:28 PM
C
carbking  Offline
Carburetion specialist
Joined: Nov 2002
Posts: 1,737
Missouri
Originally Posted by jfnar
Carbking, I'd be interested in the details on your 68. I'm also working on a 68 gmc. My first mileage check was 15.25 but I found that the choke was not opening completely so I'm hoping to do better on the next tank. I have a 292 with 390 holly 4 bbl and HEI. All the internals of the engine are stock. I have an A833 OD transmission and 3.73 rear gears. It runs about 2000 rpms at 60 mph.



Not a GM - it might be frowned upon if I posted exact details on this forum wink

But it is a half-ton, with a V-8 somewhat smaller than 400 CID with two Carter 625 CFM carbs running solid linkage producing approximately 450 HP and a 4-speed with granny low.

Will pull from idle to WOT with zero hesitation in 1st, 2nd, and 3rd. Will pull from 1100 to WOT in 4th.

Jon.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
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Moderated by  53moneypit, Woogeroo 

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