[JustLuckey]

Sorry guys for being absent for quite some time on the thread I started...between working and being a new dad....doesn't leave much room for forum following and posting. In my absence, there's been a lot of good info, recommendations, and discussion in this thread. Thanks, good reading to catch up on. Also, hello to my fellow cumminsforum and dieseltruckresource friends!

I spent quite some time looking through the aero bed cap threads...I felt like I had a bit of attention deficit disorder when trying to follow that thread that branched off to a 2nd thread, then a 3rd...then finally circled back to this one I started earlier this year.

Before I get too far into my post, I want to apologize for a inaccuracy in my initial post (as a reread it and all that followed). I originally posted that I get 24-26mpg on the highway. This is not correct as I have found out later. Let me explain....
I make several trips from PA to GA each year. In prep for the trip, I literally fill my tank at a station, return home, then use a 5 gallon container to 'top-off' my 34 gallon tank in my driveway (so I have a true FULL tank before leaving the next morning). This top off includes waiting for the air to bleed (on a quiet day, you can hear the whistle of it escaping) and rocking the truck. It will often take 2-4 more gallons after the fuel pump clicks off. Then I'll do my 800+ mile run and fuel up somewhere in SC. The SC fuel up is where my calcs are thrown off...as I don't get a true 'fill-up'...often missing the 2-4 gallon top-off. Having said that...

My trip to GA in late June 2011 had 2 fairly new mods (electric fan and cab high ARE Cap, vs. my hard tonneau cover).
I took pics of my odometer at each 100 mile mark (seen here: www(dot)cumminsforum(dot)com/forum/3rd-gen-powertrain/360834-whos-traveled-farthest-one-tank-7.html (replace dot with . ) Who's traveled the farthest on one tank? - Page 7 - Dodge Cummins Diesel Forum) until I hit 800.5 miles, where I filled up. My wife had to feed my baby boy, so I was able to spend the 15-20 mins (with the help of a very low flow setting on the pump) to bleed out the air, rock the truck, etc to get a true FULL tank of 36.65 gallons (well over the 34 gallon tank that I have) for a mark of 21.84 mpg.
Then during my trip to GA in Sept 2011, I was by myself and it included another mod, a new aFe exhaust manifold...this is was an excellent time to check my mileage. I did take pictures of my odometer, but unfortunately, I didn't remember to email them to myself like I did last time (read: backup) and my phone died the next week and realized they weren't saved on my memory card...so you'll have to take my word for it. I stayed in SC with friends this time and would be doing some city driving the next day, so I didn't hit the 800 mile mark, but would have crushed it otherwise. I filled up at 766.0 miles with 34.2 gallons for 22.4 mpg using my same 'top-off' technique. Also, my low fuel light (normally at 62 miles remaining / DTE) didn't come on until a couple miles before the fueling station....meaning I could have gone at least another 80-100 miles.

Sorry I don't have a good baseline for mpg, but I can say that I have never been able to travel those distances in the past...I remember my first trip to GA in my (stock) truck (when I first bought it in 2008), I barely made it 700 miles on a tank. Each trip I seem to be able to stretch it further and further. Any anyone that has traveled interstate 84 in PA and I-81 from PA thru VA knows that there's a lot of hills and mountains...and the upstate of SC isn't flat either. I will be the first to admit the obvious, my tests are far from 'controlled' tests, as temperature, speed, A/C use, and other factors a constantly different each time....but each time I do get further.

Let me see if I can address a few questions/issues that were aimed towards me.
I'm running on the Michelin LTX M/S2 LT235/80-17 load E tire, which is an all season / low rolling resistance (LRR) tire (versus LT265/70-17 General <Something> which was my stock tire). Not a huge difference in dimensions <1" taller and ~1.5" narrower. But these are rated at Low Rolling Resistance, so presumably more fuel efficient. The reason I didn't go with the A/T2 tire (which is also an all season tire) is that Michelin's website rates the M/S2 tire as longer wear life and more fuel efficient over the A/T2 tire.

I agree that keeping records of every fill-up and mileage is one of the best way to track mileage and effects of mods performed. But in my case, it would be very difficult. I spend most of my time on the road traveling to client sites in NYC and upstate NY (which I'll take my Camry). This leaves my wife with the truck (which she likes driving). She tends to have a heavier foot than I do, but also has our baby with her...so remembering the receipt and/or jotting down the mileage is low on her list of things to remember at during fill-up. We also use a shopper discount card that gives us $ off per gallon, but the max is 20 gallons. So once or twice a month, we only get 20 gallons of fuel, not a full fill-up. These factors make is very difficult to keep good track of fuel in/mileage out. The only time I really have full control over mileage and fill-ups is during my PA-GA drive, when I drive the whole way and do the filling up.

I somewhat agree on 'gadgets' that claim to improve mileage. I have purchased a few (what can be considered) 'gadgets', but I do quite a bit of research before making a purchase and/or modify my vehicle. On an aside, a side benefit of traveling is 'points' accumulated on my AmEx, which can be converted into $ to be used on Amazon.com. So most of my mods (my flex-a-lite fan, my exhaust manifold, and others) are 'purchased' for much less than retail. On the same line, I don't always purchase efficiency mods and labor based on a cost/benefit analysis. If I did, I probably would have just bought a smaller vehicle and call it a day. I'm after the hunt for the best mileage, not necessarily the hunt for best ROI. It may seem counterintuitive, but just like horsepower freaks don't factor ROI when upgrading for more ponies in their Mustangs, Hot Rods, etc...I'm the same way with MPGs. But I'm not willing to buy a $5k turbo or $10k tranny to gain 1% fuel economy (if one was proven to exist).

Regarding electric fan vs. mechanical/clutch fan: to each their own. In my research, it appears that the electric fan is more efficient and puts less stress on the engine. Yes, it needs electric, which comes from the alternator and/or batteries, but is the alternator demanding more from the engine when the fan is running vs the mech fan? But is that offset by having a lower runtime to cool down? I'm not looking for answers here or trying to spark more debate on this topic (if you do, please start a different thread). I decided to take the plunge and install it. (if you prefer the stock fan, then a differ on the issue, no harm done).

Regarding the question about why I have my (BullyDog GT) tuner but kept it on the stock (no added power/level 0) setting. The TOW (level 1) setting is a good all around setting that makes more power but I can't tell if it's better economy. But what I do know, is when I'm given more power (level 1, 2, 3), I have a tendency to use it more (read: WOOT!) which typically leads to worse fuel economy. Also, when I stack my programmers (with Quadzilla), when the Quad MPG-MAX is in it's default (MPG) setting, it can't be 'stacked'. So I have to leave the BullyDog on level 0. There are other Quadzilla tunes that do allow for stacking with the BullyDog, so I can use the higher level power settings.

Regarding propane (or natural gas) injection. I like this approach and the results. The results are proven in many studies that introducing a seconary fuel source that makes a more complete burn of the diesel fuel yields more power, better efficiency, and less (for most of the GHGs) emissions. This is also true for water/methanol injection. This is another topic I've done a lot of research on. In my case, I'm not too thrilled of putting a LP(or CNG) tank in my truck bed for safety reasons and taking up precise cargo room. The h20/meth injection is a little more reasonable (for me, at least), as the storage could be (at least, partially) in the existing washer reservoir (but i would probably need to add another 2-5 gals somewhere) plus the (20-50% mix of methanol) is a much less volatile solution than LP or CNG. And a 5 gallon square tank in the corner of the truck bed doesn't take up nearly as much space as some of the LP/CNG tank systems I've seen. Also, I used to make biodiesel and have a supplier for neat (clean) methanol. But (if you recall my early posts here), it would violate my rules for wanting to keep maintenance to a minimum (if h20/meth ran dry, a manual switch off is needed without 'rigging' something to be more automatic). Also, the initial cost is a big factor. $800-1000 for the system (Snow performance) that I want is a lot when there's still the methanol to buy and maintain.

In summary in my long-winded post, I'm still pondering over what to do next. Aerodynamics, Locking front hubs, h2o/meth injection, fuel/air seperator, etc....I need to put much more thought and research into these. One easy one that I haven't done yet is find and put the plastic wind deflector that installs under the front bumper on. The previous owner (for plowing, I beleive) removed it and discarded it. That may help a bit with aero.

I guess that's it for tonight. It took me almost 2 hours to write this up as I wanted to make sure all my numbers were right. Good night!