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Old 01-23-2012, 11:10 PM   #21
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So you want to get the best mileage you can or are wondering why your mileage is different from another person? This post is for you.

Things the same are not at all
Let’s start out with simple physics. Here is what Newton’s laws tell us:

-First law: The velocity of a body remains constant unless the body is acted upon by an external force.[3][4][5]
-Second law: The acceleration a of a body is parallel and directly proportional to the net force F and inversely proportional to the mass m, i.e., F = ma.
-Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear.
Breaking it down:
1. The first law states that unless you drive your truck in a vacuum, there is going to be external forces upon it. Wind resistance is most notable among the forces in driving. Other external forces include rolling resistance and drive-train losses.
2. To move forward there has to be a force enacted to overcome all those external forces. So the rate of acceleration relates to the force applied (in this case, power produced by the motor) and is inversely related to the mass (simply put the “weight”) of the truck. So to accelerate faster, you need more force.
3. The third law is for every action there is a reaction. The tire of your truck is essentially “pushing” against the pavement to create the reaction of motion. However looking back to the first law, there will be external forces working against it.

These laws are at the core of why you get the mileage you do with any vehicle. Your vehicle is doing all these things every time you are moving. So the question arises, “Joe the plumber and I drive the same truck with the same specifications, but Joe’s gets better mileage WHAT GIVES??” The driver adds a large portion of the external factors. Every time you hit the brakes, you are taking away the force that was created for motion and are dissipating it as friction with the brakes and heat. Rate of acceleration is also important. It has been debated whether a very slow acceleration or a moderate acceleration is better to create the most efficient power. I don’t have the resources to test that debate, but in general keeping acceleration to a modest level will help to get the best efficiency of the power produced. Driving route and the style of driver also contributes to mileage. I might express my driving as “highway” mileage, and Joe also expresses his as “highway” but I drive at 70mph and Joe at 55 mph. In the wind resistance (drag) equation Fd=1/2pv≤CdA, velocity (V) is squared. This means a car going 100 mph is going to have a squared amount of V more than a car going 50 mph, not just double as you may think. So even though we may compare our driving route to others, it is much deeper than we may initially believe.

The next factor that is over looked is that fact that two trucks, while the specifications are the same, are truly different. While metallurgy and manufacturing has come leaps and bounds, there are still going to be differences in two motors. We tend to look at the sides of a piston as a smooth surface. When we examine these surfaces closer, one will see the microscopic crevices that really constitute its makeup. Manufactures can get to the micron level precision on components, but beyond that level is hard to replicate. Now take those differences in manufacturing and metallurgy, combine it with hundreds of other components that constitute a truck and put it out on the road. These small differences can add up to some large variation. Once it is out on the road, compound those differences with different break-ins to further change the microscopic variation, driving style, driving route, etc and it is pretty easy to see why there are differences. I couldn’t possibly go into every little deviation in the science behind it but it gives you an idea that mileage is not something simple. Every little thing gives you a chance for better mileage, not a guarantee.

Joe still gets better mileage and his wife is better looking.

Now that the differences are understood, we can move on to getting the best mileage you can. Notice I say best mileage YOU can. This number may still not match up to Joe’s because of all those external factors. Taking what YOUR truck is, what YOUR driving patterns are, and the external forces YOU encounter along with doing the best you can to adjust to them will get you the best mileage YOU can. You may never have Joe’s mileage that’s how it is. Here’s otto457’s short list of things that can help. These are all things that greaten your chance of better mileage, but just because your wife gets implants doesn’t mean she will look like Joe’s wife.

MAINTENANCE: This includes everything, “I change my oil” usually doesn’t cut it in the maintenance department.
1. Tire pressure: easy to do and about as cheap as it gets. Maintaining the correct tire pressure is crucial to a good start on the mileage quest. Under inflated tires create more resistance, which means more force is needed to create acceleration. I do not suggest over inflation as it can create uneven wear of the tread and worse case, tire failure. Remember a fluctuation in temperature= a change in tire pressure, check it often.
2. MAF and throttle body cleaning: The MAF is critical in determining air/fuel ratios. A dirty MAF can cause semi lean/rich conditions that may not trip a CEL, but will still be less than optimal for efficiency. The throttle body can also contribute to a variation of air entering the motor causing inefficient a/f mixtures. This maintenance doesn’t have to be done too frequently (every 25-50 thousand miles), but is often overlooked.

Last edited by otto457; 01-23-2012 at 11:12 PM.
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Old 01-23-2012, 11:10 PM   #22
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3. Oxygen sensors: Another overlooked aspect especially on higher mileage vehicles. While it may never trip a CEL, anything other than the needed a/f ratio is inefficient.
4. Brakes: While braking doesn’t improve mileage, dragging brakes can take a huge toll before a problem is spotted. There’s a reason it’s part of the inspection included in the maintenance manual of your truck. Check to ensure caliper slides move correctly and the parking brake isn’t dragging.
5. ALL fluids: So you do the oil changes, that’s great, but have you thought about things like your power steering, differential, or transmission fluid? Anything that leads to a loss of power is taking it away from creating forward motion. Keep fluids in good condition and even do UOA (used oil analysis) to ensure its condition.
6. Spark plugs and ignition: Making sure proper voltage is getting to the plugs and that the gap is within range will help make efficient use of the fuel and air in the combustion chamber.
7. Fuel system: Many don’t think about the quality of the fuel they are buying. It may be the same octane, but the detergent packages of the fuels can vary. Buying top tier fuel helps to confirm a healthy level of detergents to prevent deposits. Deposits in and on the injectors can cause an uneven spray pattern and less even distribution of the fuel in the mix. Along with using quality fuels, there are several fuel system cleaners on the market. All of these products are not created the same. PEA (polyether amines) is a class of cleaners that safely and effectively clean fuel system and valve deposits and is the gold standard in the industry. I won’t endorse one product over another, but a search of PEA will give you an idea of which to look for.
8. AC usage: The AC compressor adds drag. It’s been found in lower speeds opening the windows creates less drag than running the compressor, when speeds increase the drag becomes greater from wind resistance and the AC should be used.
9. Weight: It takes more energy to create motion if the mass is greater. We drive heavy trucks, but keeping things that are not needed like “Why do I still have Joe’s barbells in the back of my truck??” out of equation helps.
10. Air filter: Notice I left this until the end of the list. Very rarely in normal conditions do we see air filters that are restricting flow. Most people are pretty good about changing, and usually over change the air filter.

MODIFING for mileage: This is a slippery slope. If you do it solely for mileage, you may end up disappointed. Don’t expect the mileage claims from most manufactures. Do your calculations based off of what real world you may see and the time for return. Doing a mod that takes 100,000 miles to recoup the cost doesn’t make sense to me. Do it for your enjoyment and let the mileage be a bonus is how I go about mods.
1. Cold air intakes (CAI): One of the most asked about modifications. In theory it seems like a good idea, less restriction will mean more power to create motion. While this is true, we have to look at what you already have in the stock system. Most stock intakes on F-150’s draw air from the fender well. It’s really a good location as intake temperatures are near ambient. No shiny CAI filter can lower intake temperatures beyond ambient, only an intercooler can cool the intake charge. Now on to restriction of filters. The stock system, even horribly dirty, can flow enough air to supply the motor. Some slight gains can come from a less restrictive filter, but usually at the cost of filtration. It depends what value you put on the rest of the internal components to allow more silica particles through the filter verses a slight restriction. There are also modifications that can be done to the stock system to maintain a high filtration level while easing restriction. Most famous of these modifications to the stock system is the “Gotts mod”.
2. Programmers: Programmers with the proper tuning can give the greatest chance at improving mileage, but also come with a cost. Even on a stock vehicle, tunes will give a better driving experience and custom tunes allow modded trucks to take full advantage of those mods. Many turn to “mileage” tunes to try to improve mileage. These tunes often times limit power however. This limited power can actually lead to worse mileage in some situations. A custom tuned device gives the best chance to see a gain. There are several trusted tuners that write F150 calibrations. A tuner will adjust a/f trims and maps to maximize efficiency. They do so by taking out the “compromises” that factory tuning has to do to please everyone, and adjust to your driving style and your specific truck. Be wary of devices that claim +4mpg and 70hp, these are scam items that aren’t actually programmers. Expect a quality, custom tuned programmer to be in the $400 range. Mileage gains can be good, but may take a long time to pay back.
3. Exhaust: Exhaust modifications are seldom to see gains as most do so for sound. Romping on the throttle has a negative effect on mileage. Systems with headers can gain performance, but little on the mileage side. See my exhaust education thread for more details on exhaust in general: http://www.f150forum.com/f11/exhaust...re-myth-78102/
4. Electric fans (Efans): Efans are a popular mod for 2008 and earlier trucks. The 2009+ trucks came with this modification from the factory for the reason of improved mileage. Replacing the stock fan is a double edged sword. While it can yield decent mileage gains; quality connections, fans, and controllers should be used to avoid issues. Mechanical fans are almost worry free, efans done incorrectly can be a thorn in the side.
There are several other modifications that can be done, but have varied results impacting mileage. These include things such as tonneau covers, under drive pulleys, and throttle bodies. One modification that has no proven gains in fuel injected operation is the throttle body spacer. On the dyno and in the real world it has no proven gains. Here is a list of other “mods” tested that show no gains according to the FTC and EPA: http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut10.shtm
5. Gearing: Many choose to go to larger tires and wonder why mileage has dropped. Beyond the obvious of adding additional resistance, the speedometer is also changed along with effective gear ratio. Changing the speedometer to read correctly, and thus make correct mileage calculations is a good first step. This can be done via a reflash at the dealer, or by any quality programmer. The issue still remains that the effective ratio has changed. Changing gears is costly and usually doesn’t make up for the mileage gain if any is seen, but your transmission will thank you by lasting longer. In general, gears shouldn’t be done for mileage if the tires, rims, and ride height is stock.


I’m sure I’ve forgotten several points and made several spelling and grammatical flaws, but I’ve spent a few hours looking at a computer screen so frankly I really don’t care. Feel free to PM me if you feel I made an error or want me to add more to this mileage excerpt. I’d like to thank bobkyle2 for alerting me to the thread and inviting me to share my automotive knowledge.

Last edited by otto457; 01-23-2012 at 11:14 PM.
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Old 01-24-2012, 12:03 AM   #23
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Quote:
Originally Posted by otto457 View Post
Iím sure Iíve forgotten several points and made several spelling and grammatical flaws, but Iíve spent a few hours looking at a computer screen so frankly I really donít care. Feel free to PM me if you feel I made an error or want me to add more to this mileage excerpt. Iíd like to thank bobkyle2 for alerting me to the thread and inviting me to share my automotive knowledge.
Its ok you took the time to post this so any error you made is forgiven

Great write up and thanks for pretty much putting everything about mods for mpgs into two posts
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Old 01-25-2012, 11:10 AM   #24
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Great write up! Thanks for taking the time!...what resistance aside from power to unloaded truck weight do you think is the greatest resistance? Parasitic, rolling, aerodynamic? Just curious
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Old 01-25-2012, 11:34 AM   #25
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Great write up! Thanks for taking the time!...what resistance aside from power to unloaded truck weight do you think is the greatest resistance? Parasitic, rolling, aerodynamic? Just curious
Depends at what velocity it is traveling. From a dead stop, the greatest resistance will be rolling resistance and driveline to overcome. This is why you can idle on a slope in gear and not produce forward motion, not enough force is being produced to overcome the resistance. At high speeds wind resistance is limiting. This is why with trucks in a vacuum theoretically have enough power to go 160+ mph before redlining in 4th gear, however when wind resistance gets to a point that there is not enough power to keep going faster.
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Old 01-25-2012, 07:38 PM   #26
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Depends at what velocity it is traveling. From a dead stop, the greatest resistance will be rolling resistance and driveline to overcome. This is why you can idle on a slope in gear and not produce forward motion, not enough force is being produced to overcome the resistance. At high speeds wind resistance is limiting. This is why with trucks in a vacuum theoretically have enough power to go 160+ mph before redlining in 4th gear, however when wind resistance gets to a point that there is not enough power to keep going faster.
Wind...need torque. I know running in OD in 30 mph winds in my truck, it will get about 13 mpg (West Texas...the wind always blows) where if I drop down to 4th, direct drive, it will actually average 14 mpg doing the same speed. Just has more torque to push it through the wind. Chevy Colorado owners know this one real well, going 70 you actually get better mileage in direct than in OD. Talk to a lot of the more recent diesel owners, wind doesn't affect the unloaded mileage really, that's what 600+ lb-ft of torque can do though.
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Old 02-06-2012, 09:44 PM   #27
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Let me tell ya'll a little story. From mid November to mid December of last year I made about 14 or 15 trips from my home in Oceana, WV to Covington, VA (around 230 miles round trip). My truck is an 09 SCAB with 5.4 and 3.55 gears and the trip was about 40% two lane roads and 60% interstate. I started out on my first trip with the cruise set on 72 mph I averaged around 16 mpg (on the computer). After a couple of trips I dropped down to about 67 mph and got around 17.4 mpg. 60 mph broke the 18 mpg barrier. On one of my last trips I sucked it up and set the cruise on 55 mph and got 19.6 mpg! Now keep in mind that I am driving in WV and VA and there are no flat roads. The terrain here is continuous up and down. On the first 40 miles or so from my home is 2-lane road. The elevation goes from about 1300 asl to 4000 asl and then back down to 2500'. Then on I-64 up to 3500' then down again to 1800' then back up to 2500' and so on. You flat landers could do a lot better than me.
Moral of the story is just SLOW DOWN. I know it's hard, I was around back when the government changed the speed limit to 55 and I did get a few speeding tickets.
It wasn't that bad driving 55 now though. It felt a little weird having a big trucks pass me but I eventually ended up catching and passing them on the next long grade.
I don't think I would like to see the mandatory 55 MPH speed limit again but I do believe it would have a big impact on fuel prices and our dependency on imported oil.
Speed is the key. The first year I had my 09 (sclb 5.4 3:55 4x4) we went to the black hills of south dakota, filled up in Rapid City, went to Deadwood the back way,(speed limit 45 to 55 mph) drove around Deadwood for 3 days then went back the same road to the same gas pump in Rapid City, 21.9 mpg. Sure more fun driving 75 or 80 though even if the mpg does drop to 18.
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Old 02-07-2012, 12:17 PM   #28
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The Ultimate MPG thread.-image-2602124811.jpg

Just added a K&n filter air flow kit to my 2011. Sounds great! Now if I can only keep my foot off the gas I should see mpg go up
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Old 02-07-2012, 09:01 PM   #29
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Attachment 82632

Just added a K&n filter air flow kit to my 2011. Sounds great! Now if I can only keep my foot off the gas I should see mpg go up

But it sounds soo good sucking that air doesn't it?
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Old 03-03-2012, 05:48 PM   #30
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im gettin like 12 in my 77, 15ish in the 79 and around 18 in my idi
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