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Discussion Starter #1
I'm a newbie who just bought his first 7.3 yesterday. I'm wondering what some of your tricks are for getting the most MPG's out of your truck.

What are some of the inexpensive ways to start with?

And what are some of the other more expensive ways to improve MPG?

If this has been discussed 10 billion times already, I apologize.

John
 

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Dave is probably going to be the most help but it all depend on how much you really want to get the economy and how much you want to sacrify for it. DAve is getting about 24-26 mpg but he has a 4"/6" drop plus a rubber airdam and a fastback along with being 2wd 6 speed and having a 3.08 final drive. Some inexpensive tricks is fill the tires to max pressure that is posted on the side wall, don't accel to fast, be smooth, If you are a stick dont understimate the power of coasting. Driving style has to do a lot on diesel engines. Then there are the small stuff like 203 THermostat. Dave will probably be able to give you more details
 

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OBS junkie
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First of all what truck/gearing/tires do you have? I hope you didn't buy youtr truck thinking you can get 25mpg everyday under normal driving. For starters the first thing I would do is get a straight pipe or free flow muffler on there. Then a homemade Tymar intake, it will pull all the air that you'll need & costs around $50. Next you can look at something like a DP Tuner with a few mild tunes on it to give you alittle more juice. If you can keep your foot out of the throttle the chip can help with mpg.
The one thing I've found that helps better than anything though is to keep the RPMs below 2000 if you can. Reving it up to 2600rpms through every gear might make you go quicker but it also cuts back your mpg as well.

Welcome to The Nation by the way!
 

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Cute and cuddly boys!
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X2 on what Cat and Infocus said. Driving style definitely has a lot to do with MPG. Ease off from a dead stop, coasting, drive smooth through the corners, and keep a steady speed.
Don't expect your truck to get in the 20's without a lot of help. This winter I averaged 14-15 mixed driving. I do expect it to increase here shortly when we get off the winter fuel. But I only expect a 1-2 mpg increase.
 

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OBS junkie
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Yep, winter will cut it down 1-2mpg on avd. Between the warmups, cold weather, winter fuel it all hurts these trucks. Alot of town driving will cut it down too.
 

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<----Simply the best.
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What kind of truck did you get? OBS:bowfast: or the not so cool Superduty:blah:

Basically what everyone has said so far. Driving like granny has helped me keep MPG somewhat decent in winter. It has been getting better though since warmups are really needed anymore. I always like when people follow me going the speed limit then haul ass and go around me. Thats when you crank thee ole TS up to the race tuen hahaha
 

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Why you calling the Superduty not cool? I think its way cooler than the OBS, but to each his own!
 

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A couple of tips:

Cetane boost additive
Light weight tires
Non-lifted truck
No canopy/open tailgate
 

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Why you calling the Superduty not cool? I think its way cooler than the OBS, but to each his own!
I get to drive both on a regular basis & like them in there own seprate ways. :ford:
 

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Welcome to the Nation, Adirondacker. You’ll find lots of good info and little BS.

Good fuel mileage is just like other performance. It is just another corner of the performance envelope. There is an old hot-rodders’ saying that goes something like: Speed is a matter of money. How fast do you want to go?” Fuel economy is the same way. There are some cheap things, but they are not as potent as the more expensive things.

Here’s some cheap stuff that works for everybody.
1. Air up your tires to the max on the sidewall. These trucks are very sensitive to tire inflation, particularly at lower speeds. I run 100 psi in my E-rated Firebombs, but I don’t recommend that for any but the truly economy-crazed. Firebombs are better overinflated than underinflated but that may vary from brand to brand.
2. Run with your tailgate up. Running with it down makes a huge low-pressure area behind the cab that sucks you back. More on beds as you get into the stuff that costs money.
3. At all costs, keep your engine RPM below 2000. The 7.3 in particular sucks fuel above 2000 RPM. For a truck with 3.73 gears and OEM-size rubber that means 70 MPH.
4. Get a pyrometer and install it pre-turbo. Drive to keep EGT below 600 degrees. This works, but will make acceleration a leisurely thing.
5. Get and install a 203 degree thermostat. Bob Riley’s Diesel Site sells one.
6. Disable your EBPV. There is an electrical connector under your turbo. Disconnect it and tape both ends up. This gains you 2 MPG in the winter but will require longer warm-up times.
7. Speaking of warm-ups: Don’t. Diesels idle so efficiently that they will simply not warm up without load. Once she has oil pressure (without it the engine won’t run) put it in gear and drive away easy.
8. If you get caught at a railroad crossing (like I seem to do all too often) or something similar where you won’t move for three or more minutes, shut ‘er down. Idling takes fuel.
9. In summer it is better to run with the AC on than with the windows down at highway speeds. Below 35 MPH, open the windows and turn off the AC, depending on conditions.

Tell us something about your rig and we can zero in other things we know works.

Configuration: 4x4 or 4x2? Regular cab, SuperCab, or Crew Cab? Short or long bed?
Transmission: Automatic or manual?
Model Year of truck It matters
Tire size and make.
Axles and gearing.


What is the mission for your truck? Some guys seem to use them as junior tractors for trailers. Some tow intermittently. Some just haul bed loads. Some use them as overgrown grocery-getters. For years, I had a hard tonneau and joked about the truck being the world’s largest VW Jetta. If you don’t have a clue, admit it. Most of us started out clueless.

How much do you intend to drive this truck? I put down 2500 miles a month. That justifies a lot of mods.

Where do you intend to drive this truck? The handle would indicate upstate NY but handles can be deceiving.

I don’t know if this is your first diesel or just your first 7.3. Diesels are different and require different thinking.
 

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Discussion Starter #11 (Edited)
Wow Dave! That was an excellent read.

A few questions to help me understand better:

1) Is a tonneau cover better than open with gate up?

2)Will larger diameter tires help me more? Like jumping up to 265 or bigger? Not sure what is on there now. Looked small like 245 or 255. (I pick up the truck tomorrow from dealer.)

3)You wrote: "Get a pyrometer and install it pre-turbo. Drive to keep EGT below 600 degrees."
Is there a link that explains how this is done? Is there a probe that attached to a threaded fitting or attaches to the pipe?

4) Does the 203 degree t-stat run the engine hotter or cooler? What is the theory behind it?

5)What is the EBPV, its function, and what is the purpose of disconnecting it? How does it save fuel?


To answer your questions, I bought a stock 2002 F250 XLT 4x4 SuperCab Short Bed with Automatic 7.3 PSD with only ~47K. The rear end felt like 3.73. Not sure what size the tires are but know they are Firestone- Transforce HT . Appeared to be maybe original and not very large (maybe 245 or 255?). Truck looks like it must have sat in a garage mostly and used on weekends. No brake controller and no signs of abuse on the bedliner. No plow. Fairly clean oasis where a trans leak was fixed with new torque converter and trans pump.
This is my first diesel. I'm a newbie greenhorn but mechanically inclined and do my own maintenance typically on my cars/trucks.

Mission:
1) I drive 140 hwy miles per day with not much of a load other than tools and occasional building materials.
2) I currently have a large heavy Coleman popup and now hope to upgrade to a trailer which I might pull on 4-5 weekends during summer and 1-2 weeks on longer vacation to national parks or where ever.

I actually live an hour south of Albany NY but spend most weekends up in the Adirondacks. Mountains might go as high at 5300 ft in elevation there. Mostly driving at lower altitudes.

Thanks for any tips you can provide.

John
 

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<----Simply the best.
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Why you calling the Superduty not cool? I think its way cooler than the OBS, but to each his own!
Because I own an OBS:D

I'm just messin with you guys though about the Superduty. My dad has a 2003 CC SB 6oh. I love the truck and all but wish he looked longer and got a 7.3.

The Exhaust Back Pressure Valve (EBPV) helps warm up the engine in the winter when it is cold. I unplugged mine a month or two ago and already saw the MPG go back to where it was before. When your driving it will sometimes start to close to create pressure to try and warm things up faster. You can tell if it is trying to do this with the feeling of loss of power.

Am I on par with that explanation everyone?
 

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Wow Dave! That was an excellent read.

A few questions to help me understand better:

1) Is a tonneau cover better than open with gate up?

2)Will larger diameter tires help me more? Like jumping up to 265 or bigger? Not sure what is on there now. Looked small like 245 or 255. (I pick up the truck tomorrow from dealer.)

3)You wrote: "Get a pyrometer and install it pre-turbo. Drive to keep EGT below 600 degrees."
Is there a link that explains how this is done? Is there a probe that attached to a threaded fitting or attaches to the pipe?

4) Does the 203 degree t-stat run the engine hotter or cooler? What is the theory behind it?

5)What is the EBPV, its function, and what is the purpose of disconnecting it? How does it save fuel?


To answer your questions, I bought a stock 2002 F250 XLT 4x4 SuperCab Short Bed with Automatic 7.3 PSD with only ~47K. The rear end felt like 3.73. Not sure what size the tires are but know they are Firestone- Transforce HT . Appeared to be maybe original and not very large (maybe 245 or 255?). Truck looks like it must have sat in a garage mostly and used on weekends. No brake controller and no signs of abuse on the bedliner. No plow. Fairly clean oasis where a trans leak was fixed with new torque converter and trans pump.
This is my first diesel. I'm a newbie greenhorn but mechanically inclined and do my own maintenance typically on my cars/trucks.

Mission:
1) I drive 140 hwy miles per day with not much of a load other than tools and occasional building materials.
2) I currently have a large heavy Coleman popup and now hope to upgrade to a trailer which I might pull on 4-5 weekends during summer and 1-2 weeks on longer vacation to national parks or where ever.

I actually live an hour south of Albany NY but spend most weekends up in the Adirondacks. Mountains might go as high at 5300 ft in elevation there. Mostly driving at lower altitudes.

Thanks for any tips you can provide.

John
Hey John welcome,

I'm 2 minutes off northway exit 33 up by keeseville/willsboro, the northern lake placid exit. You want to swing by some time I can show/explain the stuff done to my truck, or just pm me. My intent of the vehicle purchase and following mods were for long term reliability and effeciency, until I started burning veg oil and got bigger tires, now I drive around like a maniac. At 140miles/day you are a candidate for a wvo system.

Here's the math on that: you drive 140 miles/day times 250 days per year=35,000/yr. At 15mpg thats 2333 gallons. So say the wvo system cost $4000all said and done. At $4.40/gallon your pay off of system will take about 14,000miles ...6mos?

The bigger tires will kill your mileage quick. All season 265's (30") came on my truck, then I went up to 285's (32") mtr's, now I'm on 315's (35")
I lost the most going from the 285's to the 315's. I still tow 4500# like it's not there.

As said...definitaly need to get to start
1: intake, exhaust
2:guages
3:tuner
 

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First, to answer Adirondacker’s questions.

Q. Is a tonneau cover better than open with gate up?
A. Absolutely. For me it was worth a 1.5 MPG improvement.

In general the more open road driving you do, the more positive effect aerodynamic mods have. I drive about 35% urban/suburban traffic. If you drive more open road, your improvement would be greater. BTW, I have a hard tonneau for a short bed for sale.

Q. Will larger diameter tires help me more? Like jumping up to 265 or bigger?
A. No! If your tires are 245, 255, or 265-75x16 or 235-85x16 leave them alone.

This is one thing the factory boys get right. I have heard from literally hundreds of guys who have gone to bigger tires and without exception they always get WORSE MPG even after recalibrating their speedo. This seems counter-intuitive (particularly when you think about the effects of regearing) but the fact is that wheels have a rotational moment of inertia. The wheels act as flywheels. That rotational moment of inertia goes up with the square of the diameter. Everytime you pull away from a stop sign or light you not only have to accelerate the vehicle but spin up the wheel/tire combos as well. The more inertia, the more energy you have to put into them to get them up to speed. This is also why big wheels/tires tend to eat brakes. Living in snowy New York state it may be a good idea to get a second set of specialized snow tires, but keep them the same size.

Q. You wrote: "Get a pyrometer and install it pre-turbo. Drive to keep EGT below 600 degrees."
Is there a link that explains how this is done? Is there a probe that attached to a threaded fitting or attaches to the pipe?
A. Mine is attached with a saddle fitting. Some guys weld on a bung and thread it in. Check out the more performance forums. There are guys who are a lot more hip to the fine points of pyro installation than I am and I will defer to their experience. As we said at first, the Nation is a wealth of knowledge. Use it.

Q. Does the 203 degree t-stat run the engine hotter or cooler? What is the theory behind it?
A. Hotter. The theory is that a hotter running engine has tighter clearances and less leakage plus stronger (thinner) lube films and thus less friction. By putting a 203 degree stat on my 7.3 I gained 0.5 MPG. Not a big change but it is a cheap, easy and effective mod.


Q. What is the EBPV, its function, and what is the purpose of disconnecting it? How does it save fuel?
A. Engine Back Pressure Valve. It is a winter fast warm up feature. As I said the diesel engine is so efficient that it has trouble generating enough excess heat to warm itself up, so the engineers put the EBPV on the engine to artificially impose a load on the engine so it warms up quickly. It amounts to an exhaust brake. You can hear it operating – it makes a hissing sound when operating. The EBPV is controlled by both an electrical signal and a pressure sensor. The pressure sensor tend to get gunked up and the thing is actuated even when the engine is hot. Mine was particularly bad about that. It stayed shut from September to May. And because it imposes a load on the engine, it loses MPG. By disconnecting mine, I get 2 MPG better in the winter than when it was connected. Of course, it now takes about 12 miles for the engine to warm up enough to make the heater work. If that is a problem for you, plug it in at night all the time. Hard-core hypermilers (real MPG freaks) use a plug-in block heater even in the summer to avoid the energy penalty of a cold engine.
 

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Looking at Adirondack’s truck, mileage and mission, we can see some opportunity. It looks like this truck we be driven 30,000+ miles a year. That and $4 (or even $3) fuel justifies almost any expenditure if Adirondack keeps the truck more than three years.

I have been monkeying with getting better MPG since 2000, and I have found three things that work:
1. Better aerodynamics
2. Better gearing
3. Better driving

We’ll discuss “better driving” more later, but I want to hit aero and gearing for now.

Aerodynamics are actually cheap mods to clean up the wind flow around your truck. Aerodynamics are important over 35 MPH and become dominant over 40 MPH.

Some things Adirondack simply cannot do. You cannot to my knowledge slam a 4x4, so don’t worry about that. Because of the height of a 4x4 you cannot use a radical air dam like mine, even in the warm months and even if you never go off-road. Likewise side skirts will be impractical.

Some things Adirondack can do. A tonneau is marked better than an open bed. Some guys can live with one, some cannot. Hard (fiberglass) or soft (canvas) – both work for aerodynamic improvement. I discussed it some above. Better yet is a “fastback” bed cover. See my truck in the photo gallery. I hope to have a more optimized and useful version on by this summer. Stay tuned to the Nation. Just my goofy prototype improved my mileage by 1.5 MPG over the hard flat tonneau.

Something else to think about if you are handy are rear fender skirts. If your tires seem small, you probably have a big open area above the tires. This acts as a parachute. If you are the least bit handy, you can make fender skirts. Sheet metal or plastic and some sheet metal screws will do the trick. You don’t have to fair the whole rear tire just the top part that does not extend outboard of the fender. Warning! Some guy will say that fender skirts make your truck look “gay.” If that is more important than your money don’t do them. But if the money is more important…

Gearing is the big enchilada. All engines have internal friction, both from the machine elements and from pumping the fluids around. The torque penalty imposed by is fairly flat below 2000 RPM and the curve gets steeper above that. Since HP (and fuel flow) is torque times engine RPM, the HP expenditure (and additional fuel burn) is proportional to engine RPM. If you can slow down engine RPM you reduce fuel burn for a given speed. Hence… the value of numerically lower gear ratios. If Adirondack’s truck, on OEM rubber turns about 2000 RPM @ 70 MPH the gear ratio is probably 3.73:1 which is a common ratio for pickups. By going to 3.08 gears, my truck now turns only 1700 RPM @ 70 MPH. That 300 RPM (15%) reduction in engine RPM was good for 3 MPG for me. 3.08s are not available for front axles so the best Adirondack could do is 3.55:1. Here he would expect to turn about 1,900 RPM. This is a 5% reduction. My guess is that should give him a 1 MPG improvement. Maybe a better way to go is to get a Gear Vendor or US Gear overdrive unit. These are generally 0.8:1 gear sets and that is a 20% lower overall gear and should have him turning 1,600 RPM down the road. This reduction should outperform my 3.08s. Overdrives are salty - $3,000 to $4,000 installed, but if you are putting down 30,000 miles per year, they will break even in less than three years. A decent jeep shop can install 3.55 R&P sets for about $1,000 per axle.

Note that Ford now installs 3.55s as standard in new trucks, in an effort to get better MPG.

7.3 engines have fabulous low-end torque. If you are not familiar with diesels their low-end performance will blow your mind. The gearing outlined above is child’s play for a 7.3. what is not child’s play is for your automatic. If you slow down engine RPM, you proportionally reduce cooling ATF flow to the transmission cooler. Hot fluid is not good for automatics. Some guys report no problems but others trash transmissions. Maybe a discussion with an automatic guru will clarify that issue (I’m a handshaker guy so wouldn’t know). Here in the Midwest, Brian’s Truck Shop is considered authoritative by guys I regard as having a clue. He seems to think his automatics will stand up, but then he build racing automatics that withstand far greater stress than someone seeking better MPG would ever impose. Something to consider.

In your place I would reduce road load by doing the tonneau and fender skirts first then investigating gearing changes.
 

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Back when fuel was $1.40/gallon the rule of thumb was that it took 100,000 miles to pay off an overdrive with fuel cost savings. I daresay that figure is somewhat less these days.
 

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Dave, Thanks for taking the time to give us all this information. If you are ever going to be heading through ohio on 70 give me a shout, i'd love to see what you have done with your truck in person. I am just north of dayton. Thanks again for all the info!!!
 

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I think Dave eats this sh*t up!! its all good, it is nice to have someone with lots of experience and knowledge with this
 

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Hey I'm AT DAyton, oh too...
 

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Discussion Starter #20
Dave you certainly are the MPGuru!

Excellent write up and explanations.

This one is now bookmarked. Great read and education.

Do you do any of the additives such as cetane boost or 2 stroke oil or acetone to the fuel mixture?

Thanks again for taking the time to explain all that stuff.

John
 
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