Diesel mileage

[lovemysan]

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.

[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.

[lovemysan]

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.

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.

[diamondlarry]

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.

Welcome to the forum. It's about time we start getting some more Saturns.

[Sludgy]

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.