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05-24-2006, 03:11 PM
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#1
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Member
Join Date: Oct 2005
Posts: 617
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Diesel mileage
Matt, the old "Diesel mileage" thread won't come up in the new format. You still have a few bugs in the new programming.
At any rate, the F350's last fill up got 15.2 mpg, all city driving. This mileage is about 1 mpg better than before the EGR valve was replaced. The truck definitely upshifts sooner and the revs stay lower. So I may have had a bad EGR valve all along.
I just finished adding a plywood bed cover to the truck. This probably won't help much in city driving, but I'm going to test highway mileage on a long trip to northern Maine in early June. Maybe with the cover I'll get into the mid 20's. (Fingers crossed)
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06-04-2006, 06:18 PM
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#3
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Member
Join Date: Oct 2005
Posts: 617
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tonneau cover
Well, I built a plywood tonneau cover for the truck, and tested it this weekend. I took a ~700 mile trip to my camp in N. Maine.
The results were disappointing, only 19.7 mpg. This is worse that a trip last fall to N.Carolina without a tonneau. I had my tires at 80 psi, and drove under 65 most of the way. It was very rainy, which probably hurt the mileage. Anybody here measure mileage in the rain vs dry?
Curiously, I could tell from the gas gage and Scangage that the mileage wasn't very good over the first part of the trip, so I gave up trying to keep it under 65. I drove 70-75 during the last leg of the trip, and the mileage seemed to get significantly better at the higher speeds=.
This sounded crazy to me at first, but my truck is turbocharged. Maybe the turbo isn't at an efficient point at low speeds? Anybody out there have similar experiences with turbos?
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06-04-2006, 06:27 PM
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#4
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Flying Under the Radar
Join Date: Feb 2006
Location: Raliegh, NC
Posts: 1,694
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No experiences with turbos or diesels but I swear that I read somewhere that tonneau covers actually hurt FE on a truck. I dunno, just something that stuck in my brain. I'm probably just confused.
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06-04-2006, 06:37 PM
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#5
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3 pedals>*
Join Date: Oct 2005
Posts: 2,024
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Quote:
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Originally Posted by krousdb
No experiences with turbos or diesels but I swear that I read somewhere that tonneau covers actually hurt FE on a truck. I dunno, just something that stuck in my brain. I'm probably just confused.
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same here. Mythbusters also did a piece where it shows that the tailgate up was better than tailgate down.
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06-04-2006, 07:14 PM
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#6
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I should be WORKING now
Join Date: Dec 2005
Location: Eastern Ontario
Posts: 4,791
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Quote:
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Originally Posted by krousdb
I'm probably just confused.
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Yup, I'd say confused! Tonneaus are better for FE. To test this properly, you'd have to do back-to-back runs, not just compare two separate trips under different conditions.
Diesel & turbo info - I'm sure if you headed for a VW forum you'd likely find plenty of diesel specific info.
Surely there's a forum for your specific truck somewhere, isn't there? |
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06-05-2006, 08:59 AM
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#7
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Member
Join Date: Oct 2005
Posts: 617
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F 350 mileage forums
Quote:
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Originally Posted by MetroMPG
Surely there's a forum for your specific truck somewhere, isn't there?
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Yes, there are a bunch of diesel truck forums out there. I've been there. Unfortunately, about 90% of their respondents eat bananas, and their knuckles touch the ground. 
At Gassavers, the average IQ is at least 30 points higher. |
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06-05-2006, 10:13 AM
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#8
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I am a banana
Join Date: Mar 2006
Location: Western Wisconsin
Posts: 1,481
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yes, the turbo sould work best at higher engine speeds, and with that added air bost your efficency, you said you have a scangauge, so why not try different speeds, on the same road, and find out where you hit your peak? your engine might not be tuned to run efficently at low speeds, after all, who drives 65 any more?
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06-05-2006, 10:33 AM
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#9
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Flying Under the Radar
Join Date: Feb 2006
Location: Raliegh, NC
Posts: 1,694
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Quote:
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Originally Posted by Sludgy
Yes, there are a bunch of diesel truck forums out there. I've been there. Unfortunately, about 90% of their respondents eat bananas, and their knuckles touch the ground.
At Gassavers, the average IQ is at least 30 points higher. |
I'm not sure if that was meant as a compliment or ann insult.  |
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06-05-2006, 10:35 AM
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#10
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I should be WORKING now
Join Date: Dec 2005
Location: Eastern Ontario
Posts: 4,791
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And bananas are one of my favourite foods... 
I would have thought the turbo advantage would come from increasing power at low RPM where losses to friction are lowest. A non-turbo would have to rev higher to develop equivalent power.
A turbo CVT vehicle seems like the best mix of technologies to me.
Last edited by MetroMPG : 06-05-2006 at 10:37 AM.
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06-09-2006, 01:25 PM
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#11
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Member
Join Date: Jun 2006
Posts: 650
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I can get 22-24 mpg on the highway at 65mph or less. I have a 95 f 250 psd, auto, 4.10s. Your city mileage sounds really good to me. I've always thought that less turbo spool meant more mileage. After all a turbo is a restriction and spooling is causing backpressure. But you don't want to lug a turbo diesel you'll make more heat and burn more fuel. My 91 dodge cummins seemed to like no boost at highway speeds better. I swapped to a smaller turbine housing and lost a maybe 1 mpg. At 65 it would hover between 5-7lbs of boost with the small housing verses no boost with stock.
Do you think possibly you were dealing with a headwind on that long trip?
Your right about the people on the diesel truck forums. Its all about what 150hp chip your running. Have you thought about a chip or programmer for mileage. If you bump the timing a little it helps mileage. I'd also run a straight pipe or a donaldson muffler(a BIG one). Maybe an intake too. Thats about it for mileage.
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06-09-2006, 02:57 PM
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#12
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Member
Join Date: Oct 2005
Posts: 617
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That trip to Maine was mostly with a stiff tailwind, a tonneau, and I drafted semis for a while.
My F350 is a 6.0 with 3.73 gears. It ought to get better mileage than a 7.3 with 4.10 gears, wouldn't you think?
I thought about buying a chip, but the 6.0 has a lousy reliability record. Mine has already has had 2 warranty repairs. I don't want to void my 100,000 mile warranty. So, I'm basically screwed.
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06-09-2006, 05:58 PM
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#13
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Member
Join Date: Jun 2006
Posts: 650
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Quote:
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Originally Posted by Sludgy
That trip to Maine was mostly with a stiff tailwind, a tonneau, and I drafted semis for a while.
My F350 is a 6.0 with 3.73 gears. It ought to get better mileage than a 7.3 with 4.10 gears, wouldn't you think?
I thought about buying a chip, but the 6.0 has a lousy reliability record. Mine has already has had 2 warranty repairs. I don't want to void my 100,000 mile warranty. So, I'm basically screwed.
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I drove very gently to get 23.9 mpg. The truck is a 2wd. Temps outside were mid 60s with low humidity. That was full to the top of the filler neck. The truck might be 3.73 gears. 80 mph is 2750 rpms.
Thats why I loved my old cummins so much. Its hard to beat mechanical injection. But alas, a friend put gas in it and the I-pump went down, so now I drive a saturn. Kinda sad to me, really. |
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06-09-2006, 10:42 PM
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#14
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FE nut
Join Date: Sep 2005
Location: Elkhart, IN
Posts: 1,193
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Quote:
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Originally Posted by lovemysan
I drove very gently to get 23.9 mpg. The truck is a 2wd. Temps outside were mid 60s with low humidity. That was full to the top of the filler neck. The truck might be 3.73 gears. 80 mph is 2750 rpms.
Thats why I loved my old cummins so much. Its hard to beat mechanical injection. But alas, a friend put gas in it and the I-pump went down, so now I drive a saturn. Kinda sad to me, really.
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Welcome to the forum. It's about time we start getting some more Saturns.
__________________
Horsepower is how hard you hit the wall, torque is how much of the wall you take with you.
2007 Prius,
  
Team Slow Burn
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06-11-2006, 09:29 AM
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#15
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Member
Join Date: Oct 2005
Posts: 617
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I finally got around to some basic F350 6.0 diesel mileage tests with the Scangage. All tests were at about 60F around the same 12 mile round trip.
Speed ------- Bed conditions-------- Mileage
50 Tonneau 24.9
70 Tonneau 17.2
60 Tonneau 21.6
60 Tailgate down 22.0
60 Tailgate up 21.6
I guess my earlier theory that diesel mileage might get better at some turbo "sweet spot" isnt' valid.
And the tonneau cover didn't do anything for mileage. The tailgate down may have helped, but the difference is too small to say anything definite.
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