i run no more than 72 mph in my 19' steel bed Jerr-Dan pro loader, and i can say that 12 mpg has been harder to attain than the holy grail!

normally i see 8.3-10.8 on an average of highest and lowest.

i'm getting ready to invest in an OD unit to try and improve mileage, exhaust is almost ready to be installed, and i'm thinking about a chip, but i'm not going to invest in any of the programmers/chips until i can verifyl that i WILL see an improvement one way or another, i want my truck to be more powerful, but if i can keep the same power with more mileage i'll be more than pleased!

[/rambling]

 

I've gotten as much as 24 mpg (no lieometer) at 58 mph, and as little as 19.7 at 65 mph. Just completed a 5000 mile trip and the best I managed was 23.4. The only change I made before this journey was the Kwik Mod. I also switched from Rotella to Castrol. Do not know why I was not able to top 24 mpg even once during this long *** drive except for maybe the outside temperture being quite cool. I do know that just a few mph change will make a drastic improvement in or loss of mpg.

 

MYTH BUSTERS......on Discovery..... LOL

 

First - I related what I remembered of a university windtunnel aerodynamic study that used scientific procedures under controlled conditions. The study did NOT say how to apply them.

Second - I did give my opinion how to apply them - try tailgate-down for yourself, but keep CAREFUL records over an extended period of time. Just lowering a tailgate for a 100-mile run down the freeway may be an indicator, but it proves nothing. By the way, while I got better mileage with tailgate down, I really don't recommend it - spend the money on a bedcover. That's where the biggest improvement is anyway.

Third - Mythbusters are fun, and what they do is entertaining and often correct. BUT - they are there for entertainment purposes - their 'studies', while more carefully done than the average person would consider necessary, would not stand up to the scrutiny of a peer review by the scientific community where repeatability of results are essential.

Fourth - Unless proper controls are carefully used during an experiment, results range from questionable to dubious. Why do you think there are so many alleged "studies" by manufacturers that claim that the new Thingmabob from Doodad, Inc. will boost your mileage by some huge percentage?

Fifth - I disagreed with what what was said by referring to a couple of studies I had read. At no time did I personally attack anyone - yet you have to go negative and refer to my 'whining' about reliability of experiments. What is the point of that? Why go personal?

I have been on a number of forums, and this one is the most helpful and friendliest I've visited yet. Why would you want to change the tone of the forum?

Why not refer to scientific studies that support your point of view?

For instance, a 2004 University of Michigan test (linked here) aggrees with the tailgate up vs. no tailgate/tailgate down conclusion. The report conclusion states that, according to their simulation, pressure behind the tailgate is greater than in front of the tailgate, so tailgate up "will reduce drag". But there are two things in their study I didn't like - their airflow model is only setup for a tailgate that is missing, and it does not take into account airflow separation effects of a lowered tailgate, something that was addressed in the study to which I referred. Also, their airflow simulation model showed a 30% reduction in drag with a bedcover - a number NOT substantiated in windtunnel tests. They even state that windtunnel testing should show lower results - if the drag reduction is so innacurate, what else is wrong with the model?

I'm still searching for the windtunnel tests - of course, now it is time for me to whine about not enough time - but I haven't yet located any in the limited time I've had on the net since yesterday.