12V vs. 24V fuel economy?

[LSMITH]

I guess I will bite and be the first 24V'er to offer his side. I get over 20 MPG on the highway between 65 and 70 MPH. At 55-60 I get over 22, over 75 is 18 and it keeps going down as I go faster. I am more than happy with my fuel economy, it is better than I had hoped for when I bought it.

I would think that the 12V that gets MPG better than mine is hard to find. I also think that on average a 12V with the 3. 5 gears will get better economy than the average 24V with either gear ratio. As mentioned earlier the TDR article on BSFC explained it pretty well, but specific curves for the 24V do not exist as the fricken computer can never make up its mind as to what it is doing.

 

[Cummins Corvette]

LSMITH- I get 1-2 more mpg on the highway at each speed than you do IF I don't stop and let it cool down much. It is the average mileage, going to work and back, that is killing me. I went on a test run at 82 mph for about 130 miles and got 18. 7. That was continuous running though, only slowed down to turn around. If I go that fast on trips I get around 18. I recon it is cuz of all the stopping.

Oh ya, that was before I went to BC and visited Bill and Piers. I'm sure it would be less now.

I seem to have lost about one mpg since I went from the 180 injectors to the 215s. That is the reason I am so conserned about getting some DD3s.

 

[TomGolden]

Well, let me throw my 24V figures in here.



Immediately after I bought my truck, my dad and I towed his Toyota 4x4 up to Teton Park in Wyoming to hunt Elk. Round trip from his house to Wyoming was 2200 miles with his Toyota in tow. Truck was bone stock. 16. 0 MPG every mile, going about 70 MPH all the way, both directions.



Truck was bone stock until 12. 400 miles, when DD stage 3's, EZ, 4" Jardine and Psychotty were added. Ever since then, mileage has gone between 17. 5 - 19. 2 MPG, depending on how I get to drive it. Daily work commute (20 miles each way) in traffic on the highway is around 17. 5 - 18. 0. When I drive down south to visit family, I go down highway 5 and keep it steady at 80 MPH (2250 RPM) and it has been as high as 19. 2 MPG.



I have maybe 200 pounds of tools in the toolbox, and almost never haul much else, and except for the Toyota, have never towed anything.



Installed the Comp box about 3000 miles ago, so don't have a real good feel for how it has affected MPG yet, as I have run it at several different levels. Truck now has 33,500 total miles.



I'm fairly happy with my numbers, although I'd like to top 20 MPG sometimes



Tom