Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - 1987 Ford F250

Ok, so my night is boring enough I'll just start this now instead of waiting to have it running again (starter took a dive).

As I said in my intro thread, I a mechanic by trade, and I just stepped up to this from a 98 Ranger (28mpg hwy @ 70mph fully loaded). From a business standpoint, I'll be able to offer more to my customers, in the form of hauling more tools with me, more supplies, and with the larger truck, I can also offer hauling services such as pulling boats out of the lake or transporting vehicles or trailers. From an economy standpoint, my wallet is still screaming rape. The previous owner of this truck claims an 18mpg hwy rating, and I get the impression he drives like I do, so that's not too shabby a number for a truck that came off the scales at 6100lbs with me and my tools loaded up.

Ok, here's what I'm working with. Here's the truck, and a sampler of my typical daily load (everything that stays on the truck). This isn't everything, but it gets the point across.
http://i.imgur.com/IisuvVi.jpg
http://i.imgur.com/yqy6n5p.jpg
http://i.imgur.com/ojA2CLD.jpg

Ok, so that's the starting point. One big ass truck (compared to my Ranger), with a big ol' motor (6.9L of diesel snorting cast iron), and the aerodynamics of a chiseled brick. WOOHOO!! Now I've seen the thread talking about using a trailer vs a bigger vehicle. I do have a trailer, and while I could have setup everything upon that, I would then have had to take it with me on EVERY service call, rather than just the few that might require me to bring the customer equipment back to the shop. That would have dragged down my mileage in a worse fashion.

My goal with this is to do 25mpg or better on the highway, and 20 or better in town. Considering what this truck is currently rated at (figures taken from various personal inputs around the web), I don't see this being an unreasonable goal. So now lets break it down into categories or what I can do, what I want to, and what's out of the question.

First, what can I not do? What's out of the question?I cannot shed weight. As much as I love a good workout, I'm not loading and unloading my truck on a daily basis. One, I never know when I'll get a call to come right away. Two, I tend to cross territories and stop on the side of the road frequently (tow truck territory), and if the tools aren't with me, I make no money. This is my daily driver, it is also my bread and butter.

Second, what do I want to. One of the first thing's I'm planning to do is replace the factory bed with a flatbed. Yes, I understand this will mess with the aero of the truck, I have some ideas on that that I will get to in a minute. On this flatbed I will have cabinets on the sides, top and bottom, to hold my tools and supplies, leaving me with a wide open bed to haul cargo and equipment. This will also give me the benefit of being able to keep my equipment on the truck and still be able to haul large trailers, such as goosenecks or 5th wheels if I ever install a hitch for either. That's not directly related to my work, but I love a good roadtrip and don't mind hiring myself out once in a while. However I do put on a lot of highway miles going to and from customers (I provide service to my county and surrounding counties).

Ok, let's break it down from there.

Let's start with drivetrain.

My truck is powered by a 6.9L IDI diesel. I'm fairly limited on what I can do here. I can switch to an electric fan, I plan to upgrade to hydroboost braking and eliminating my vacuum pump, and I can run intake tubing from the air cleaner housing to somewhere on the front of the vehicle for a cooler, denser air charge. That is about the limits of my engine mods, short of swapping in a 7.3 w/ turbo (factory or Banks). Yes, I could also add a switch to turn my alternator on and off, but I rather like having a stereo in my truck (I'm relatively modest in my systems, but they're still there), and I feel that eliminating the vacuum pump will reduce loss more than the alternator would. I'm also a big fan of lighting, and being lit at all times. Between that and the stereo, it wouldn't take long to drain both batteries.

Transmission is a manual, so the drag and parasitic loss aren't present here (compared to an auto).

Rearend (truck is 2wd) gearing is 3.55 in a Ford/Sterling 10.25" axle, so it's already relatively economic. I'd love to go closer to 3.00, but the 3.55 is the lowest available gearing for this axle. I'm led to believe that the factory did offer one ratio that was closer to 3.00, but a lucky junkyard score will be my only hope. My only options for a gearing change to lower my cruising rpms are a GearVendors (expensive), an axle swap (still relatively expensive), or taller tires (lucky me, I need new ones by winter anyway). So we'll move to the tire selection.

Current tire size is 235/85-16, load range E. Being a big, heavy diesel that will regularly see loads (scrapping runs, towing, etc), I will not be going to a skinnier tire. If anything I'll actually be going a little wider. Yes, this would typically add to aero drag, but I'll discuss that later. I've been talking to Christ about this one. With the kind of miles I might start racking up, I'd like to move to a tire selection that will last a long time, be durable, and will have a load rating equal or greater to stock. So we've been discussing moving to semi tires. My current tire size is 31.73" tall, the tires I'm looking at (245/70-19.5) are 33" tall. I ran this through a gear calc, and assuming I cruise the highway at 65, my stock tires will keep me about 1890rpm. The 19.5's would put me about 1800-1810. This is 80-90rpm lower, or 4.25-4.75% lower. Not a dramatic decrease, but still fairly considerable (keep in mind max hp @3600rpm, max redline supposedly 4k rpm). The 19.5 tire combo will weigh about 100lbs or so per corner. My current spare has an improper tire size on it, 215/85-16, which weighed in today at 71lbs (tread is almost worn). Between the size difference and manufacturing tolerances, we'll say the 235/85-16 weighs 75lbs. So now we have a rough idea of 25lbs difference between the 19.5 and the stock 16.
This swap is not yet set in stone, it is just something I am floating as an idea.

Ok, what I'm doing, drivetrain, lets move on to electrical.
There's really not much to be said here. The diesel is fully mechanical, the only electric it actually consumes is the glowplugs and starter, and the fuel cutoff solenoid. Beyond that it's just lights, gauges, and my stereo. I do plan to upgrade to LED everywhere possible, and for the nature of my work there will be additional lighting, also LED. Obviously my work lighting will not be on during driving, so this wont be an issue.

Aero. Here is probably the biggest thing I can do for this truck. Buckle in folks, this will probably be the longest part of this post.
As I said earlier, I am planning on replacing the factory bed with a flatbed. Ideally my flatbed will be 7ft wide and 8ft long. Yes, this will stick out past the cab sides. Ok, let's start at the front of the truck and work our way back, shall we?

Bumper. With some of the things I carry with me (chains and jumper cables), I was initially planning on building a storage bumper, a box with an air dam below it. This bumper would have been angled inward from the top, and would have angled back on the sides. While browsing on here I came across a Blazer build by Oil Pan 4. He installed a sectioned Peterbilt bumper to use as an air dam. I like this idea more than my bumper, and plan to emulate it. I still require the storage up front for my chains and jumper cables, so the bumper will mount several inches forward of the grille and frame, so that I may implement the storage boxes in the space between. To help aid the aero, I plan to mount the bumper an inch or two above the stock bumper line, and fold the top over, make an angled lip from it. I feel this will help direct air up and over the hood (which also has an angled front). Said bumper will also be no closer to the ground than 8". I feel this will still aid in preventing the airflow under the truck, while allowing me suspension travel and clearance over speedbumps and potholes (some places I've been have some damned nasty potholes).

Moving back, wheels. As much as I'd love some good looking wheels, or even painted steelies with nice trim rings and center caps, moon discs will be better for aero. I can always paint those instead!

Little further back, visors. I do not know if they hurt or help aero in anyway, but I will have the vent visors on my windows, and I would love to have a Lund visor over my windshield. Does anyone have any experience with either of these helping or hindering airflow/aero? I'd love to hear from you about it.

Getting to the bed and it's obvious aero or lack thereof. As I mentioned earlier, the bed will be sticking out past the sides of the cab. To combat this, I had planned on "wings" attached to the cab behind the door and spreading out to the corners of the bed. since the toolboxes obviously wont be as tall as the cab, these "wings" would taper to a point from the top of the toolbox to the top of the cab. If anyone has anything to say about this, please chime in. I don't have it done yet, so I cannot tape streamers to the truck and see how well this would work or not work, so I'd love to hear what you think I might see with this.

Rear wheels. Along with wings on the cab to help blend to the bed, I'll also have skirts to cover the wheels.

Rear aero. I've been thinking about it, and for highway trips where the bed won't be stacked full of things, or at least wont be overly stacked with things, I was thinking it would be easy to setup a quick to setup/collapse kamback. Collapsible poles to hook to the headache rack and pin to the top of the toolboxes, and a rolled up cover to snap down over the frame and sides. When not in use, the poles slide into themselves and drop down on top of the toolboxes, and the cover would rollup and be tied to the top of the rack. Out of the way for daily work, and able to be setup/tore down in mere couple minutes.

Lastly, belly pan. Even with a fairly deep air dam of a bumper, I still plan to belly pan as much of the truck as possible. If nothing else, it will at least make cleanup of road grime and winter salt very quick and easy.

Let's see. Drivetrain, electrical, aero. I reckon that's about it. The only other thing is a possible waste motor oil conversion, but that's a conversation I'll be having over on Ford-Trucks with fellow IDI owners. Any changes I make in that regard, I'll definitely document here though.

So that should just about wrap it up folks. That's my truck, that's what I have planned, and what I'd like to do. I'd love to hear from everybody about my ideas and how well they'll do or how much they suck. I have a realistic goal of 25mpg highway, with a dream of maybe touching 30. Let's see how close I can get!