Fuel economy mods

[FordGuy100]

So, like I said in my other thread, I'm keeping this old beast. But with the high cost of diesel fuel, I'm sure fuel economy is weighing heavy on everybodies mind.

So lets start this thread to help each other out with fuel economy mods, and I will be the guinea pig (or however the heck you spell that). I have an $800 budget, but will only be spending that on items known to work.

So my first area of interest is tires. I am currently running 285/75/16 E tires, I like the size, but not the tire themselves, they throw rocks like crazy. But with fuel economy on my mind, I'm thinking a tire about the same height, but narrower would be a better idea, plus with a more street oriented tred. Any opinions on tire size/brand. I may not be doing this mod first, because it is spendy.

Second, air pressure in tires. Should one inflate to max air pressure to get the best fuel economy? I'm thinking yes, and I think I should air up my tires some more in the meantime.

Thirdly, Fuel mods. I'm thinking new/remain injectors and IP's would yield the best fuel economy, correct? I cant affoard an IP, but I have G code injectors, used, already. Do you suppose I would see a gain, if I had them tested, and remained if need be?

Fourth, Intercooler. I've heard that EGT's around 600* or less is optimal for fuel economy. Would an intercooler setup be worth it to lower EGT's to get better fuel economy? I wouldnt turn up the pump or anything, or adjust my boost, just put on an intercooler.

Fifth, Thermostate. Would a new thermostate, like the 203* stats that are sold for PSD's, help fuel economy? My truck runs around 190-200*, I've never seen it above that, even towing.

Sixth, Synthetic fluids. Is it worth it to swap over to synthetic fluids, I mean is the cost advantage there? Should I do all the fluids, motor, tranny, transfer case, diffs?

Seventh, Wind deflectors. Would it be a good idea to build up a wind defletor to go under the bumper, and go down to around the front diff area, kinda like the pre-runner trucks have. I'm thinking you would see a decrease is wind drag from all the stuff under there, therefore an increase in fuel milage.

Eighth, Gears. Should I swap to 3.08's? If I can do that, that is, in which case I should ask, is it possible to put 3.08's in my Dana 70 and Dana 44HD?

Ninth, filters. Should I put a bypass oil filter on, this might just save money in oil changes by extending the interval though...but thats still saving money.

Tenth, ZF-5 speed. Is it worth it to do this swap, if so what kind of increase am I looking at?

Eleventh, intake. Should I build up my own intake, or is the ATS intake good enough?

Lets get this ball rolling and figure some of them (the cheaper ones first ) out .

 

[towcat]

if you have $800, start with spending $100 for the parts in this thread.
http://www.oilburners.net/forums/showthread.php?t=22935
I have a couple of used electric fuel pumps and a 19gal rear tank off a commercial chassis F450. Otherwise, I am ready to filter on the run.

 

[FordGuy100]

if you have $800, start with spending $100 for the parts in this thread.
http://www.oilburners.net/forums/showthread.php?t=22935
I have a couple of used electric fuel pumps and a 19gal rear tank off a commercial chassis F450. Otherwise, I am ready to filter on the run.

Yup, I'm planning on running at least a 50/50 mix WMO/diesel. Thats in my other thread .

 

[big van]

Proper air pressure always saves money. Better MPG & longer tire life. I run about 5psi below the tire rating unless hauling alot of weight. Check the pressure once a month or every oil change which ever comes 1st. Also the best MPG gain is still under the right foot. Take er easy!!

 

[FordGuy100]

Proper air pressure always saves money. Better MPG & longer tire life. I run about 5psi below the tire rating unless hauling alot of weight. Check the pressure once a month or every oil change which ever comes 1st. Also the best MPG gain is still under the right foot. Take er easy!!

Thats what I figured. I should air mine up, I'm thinking they are a little on the low side.

And yes, the right foot is the main culprit. Lately I have been getting 16mpg constantly. So I figured if I did these mods, and drove the same, then it would show how much of a difference they made.

 

[TLBREWER]

Justin

You've got some good ideas there. I think you're on the right track in some ways. the problem with the IDI's obviously is the lack of precise fuel management like on later model trucks. So...new injectors and IP yielding the most efficiency would be the obvious choice when money permits. One thing to keep in mind is that "high performance" can also mean more efficient if used respsonsibly. A more powerfull engine is usually the result of a more efficient system. Along those lines, one thing you didn't touch on is fuel filtering. I don't know how effective it would be on an IDI, but on high pressure fuel systems (my DMax operates at 30,000+ psi) there are secondary fuel filtering kits that remove the "air" and micro-bubbles and contaminants from the fuel. This improves the lifespan of the IP and injectors, increases output by 30-40hp, and increases fuel mileage on the HP fuel sytem equipped trucks. Like I said, not sure what effect this would have on an IDI, but it may be worth trying.

Without precise fuel management, the best thing you could probably due to increase efficiency is heat management. Since every engine is different, this would be an ongoing experiment to see what works for you. Synthetic lubricants to reduce friction is definately something to consider...all the way through the drivetrain. Intercooler and cold air induction would definately be on my list of to-dos. Make sure all your suspension components, etc are well lubed to ease rolling resistance.

While on the subject of rolling resistance, you mentioned tires. When it's time for new treads on the DMax, I'm hopefully going to be putting on 255/85-16 Cooper ST's. Although it's not a popular tire size (yet), they have been gettiing good reviews. There are only about a half dozen manufacturers that make a streetable tire in this size. The benefits are narrower width which makes them better in snow, etc. and less rolling resistance. Yet they still have the height of your 285's so you will maintain the "look" and gearing advantage of a taller tire. They will work on your 8" rims as well.

Gearing. Unless you can afford an OD, not much you can do there, but keeping RPM down is one of the single best things you can do for mileage. My DMax has the 6sp Ally. If I set the cruise at 65MPH, I'm turning barely 1500 RPM and get about 23MPG. On my old '92 IDI with an ATS, the magical number seemed to be about 1800-1900 RPM. Below that I could get 18-19 MPG with the cruise set. Above that (75MPH) you could watch the gas gauge go down. If you have cruise control, make sure it is in good working order. On flat terrain this can aid mileage somewhat because your calibrated foot doesn't due as good as cruise. On hilly or mountainous terrain, I usually kick it off because it is too erratic.

Ok. I'm done blabbing.

Tom

 

[Diesel JD]

I wonder if a fuel management gauge like they have on boats would tell you anything, it wouldn't actually do anything except let you adjust rpm and driving style to match with your best fuel economy. For $800 I'd be looking for a used US Gear/Ranger/ GV or some other aux. transmission. Since you have a fairly long commute to school and you'll be driving a lot this summer, it would pay for itself pretty quick if you got a good deal.

 

[FordGuy100]

Justin

You've got some good ideas there. I think you're on the right track in some ways. the problem with the IDI's obviously is the lack of precise fuel management like on later model trucks. So...new injectors and IP yielding the most efficiency would be the obvious choice when money permits. One thing to keep in mind is that "high performance" can also mean more efficient if used respsonsibly. A more powerfull engine is usually the result of a more efficient system. Along those lines, one thing you didn't touch on is fuel filtering. I don't know how effective it would be on an IDI, but on high pressure fuel systems (my DMax operates at 30,000+ psi) there are secondary fuel filtering kits that remove the "air" and micro-bubbles and contaminants from the fuel. This improves the lifespan of the IP and injectors, increases output by 30-40hp, and increases fuel mileage on the HP fuel sytem equipped trucks. Like I said, not sure what effect this would have on an IDI, but it may be worth trying.

Without precise fuel management, the best thing you could probably due to increase efficiency is heat management. Since every engine is different, this would be an ongoing experiment to see what works for you. Synthetic lubricants to reduce friction is definately something to consider...all the way through the drivetrain. Intercooler and cold air induction would definately be on my list of to-dos. Make sure all your suspension components, etc are well lubed to ease rolling resistance.

While on the subject of rolling resistance, you mentioned tires. When it's time for new treads on the DMax, I'm hopefully going to be putting on 255/85-16 Cooper ST's. Although it's not a popular tire size (yet), they have been gettiing good reviews. There are only about a half dozen manufacturers that make a streetable tire in this size. The benefits are narrower width which makes them better in snow, etc. and less rolling resistance. Yet they still have the height of your 285's so you will maintain the "look" and gearing advantage of a taller tire. They will work on your 8" rims as well.

Gearing. Unless you can afford an OD, not much you can do there, but keeping RPM down is one of the single best things you can do for mileage. My DMax has the 6sp Ally. If I set the cruise at 65MPH, I'm turning barely 1500 RPM and get about 23MPG. On my old '92 IDI with an ATS, the magical number seemed to be about 1800-1900 RPM. Below that I could get 18-19 MPG with the cruise set. Above that (75MPH) you could watch the gas gauge go down. If you have cruise control, make sure it is in good working order. On flat terrain this can aid mileage somewhat because your calibrated foot doesn't due as good as cruise. On hilly or mountainous terrain, I usually kick it off because it is too erratic.

Ok. I'm done blabbing.

Tom

There we go, now we got some ideas rolling in .

Okay, filtration. I kinda hit on it, with a bypass oil filter, but not on fuel. If it makes that much of a difference in a Dmax, then it might be worth trying on my truck. Couple questions then are, what kind of filtration, just another filter, or is some fancy expensive filter that would be hard to get ahold of?

I'm thinking synthetic would help out a ton in my drivetrain. It may cause leaks in the begging, but in the end, I think it would be worth it. It would be nice to get a good 1mpg out of switching all things over to synthetic.

Suspensions is another place I didnt think about, I will be sure to grease everything up. That is a good idea, and is basically free . Maybe new wheel bearings while I'm at it, eh?

Thats what I was thinking, a tire like that. As much as I like my size tire, I do have to realise that the wider the tire, the more rolling resistance, and the less MPG. So that is something to look at to, but for some reason I have 295/85/16 on my mind, but that might be to tall or not available at all .

Gearing, I was thinking swapping to 3.08's, but that would get spendy. I just did some math, and it looks like a ZF-5 speed swap, with 33" tall tires, considering the overdrive is .85, would put me at about 1700rpm's at 55mph, which sounds good to me . I should then ask, what is the overdrive ratio of the ZF-5 speeds?

Lets keep these idea coming.

Another subject we havnt touched on is injectables, is propane and the such actually worth it fuel economy vs cost wise?

 

[tractorman86]

for your set up i would think w/m inj is the way to go but i've got no experience with it myself. i am paying VERY CLOSE ATTENTION to this thread. first thing i need to get my other tranny put in and install the blow drier.

 

[93turbo_animal]

you have to be careful with changing your gearing or addind overdrives for one thing an OD unit adds friction which is bad. In a diesel magazine they tested stuff on a 6.0 and actually lost several MPG when they added an OD unit cause it was below the optimum RPM range. there was another magazine that was trying whatever they could think of to increase mpg they folded the mirrors in made covers for the rims to block all the holes and smooth them out. They used packing tape to seal all the cracks and seems and they put a block under the go pedal so they could not get carried away on take offs. I can't remember exactly the specifis now but I beleive they were in the low 30's with a 1 ton dually dodge

 

[FordGuy100]

for your set up i would think w/m inj is the way to go but i've got no experience with it myself. i am paying VERY CLOSE ATTENTION to this thread. first thing i need to get my other tranny put in and install the blow drier.

I was thinking intercooler, so that it cools it down all the time. Water/**** you only really use (or most people do) when your EGT's are fairly high, over the 600 degree mark, when towing ect...I was thinking the intercooler would cool down the EGT's some while just normal driving around, because the cooler the EGT's it seems, the better the fuel economy...to a point.

you have to be careful with changing your gearing or addind overdrives for one thing an OD unit adds friction which is bad. In a diesel magazine they tested stuff on a 6.0 and actually lost several MPG when they added an OD unit cause it was below the optimum RPM range. there was another magazine that was trying whatever they could think of to increase mpg they folded the mirrors in made covers for the rims to block all the holes and smooth them out. They used packing tape to seal all the cracks and seems and they put a block under the go pedal so they could not get carried away on take offs. I can't remember exactly the specifis now but I beleive they were in the low 30's with a 1 ton dually dodge

I've read both of these. Our motors make there torque around 1600rpm's, thats why I was thinking it would be a good idea to put in a ZF-5 speed. With my 3.54 gears, and a .85:1 5th gear (or so I'm guessing), it would be me at about 1700 rpm's at 55mph (which I will be driving at, to save fuel ). 60mph would be like 1850rpm's which sounds good to me

And I also saw the dodge one, and was amazed at the fuel economy it had. But, I dont think I wanna go as far as taping my truck up, and putting cardboard on it .

 

[92F350CC]

I believe the ZF-5 has a .71 OD ratio.

 

[RLDSL]

an OD is only going to mess you up on fuel mileage due to being in the wrong rpm range when you are towing. I found that on my truck I get better fuel mileage towing my 5er in 4th than in 5th, even though 4th is wound out ( but pretty soon I'll have my Spicer 3 speed Aux tranny in there and I'll be able to split those gears and I'll have a nice gear right between 4th and 5th that'll be just right
But when running empty, a diesel will idle down the road in just about any gear ( and I'm really going to like that double OD running empty
If you stuck a 5 speed on the thing , it would help with your fuel situation, taller gears in the diffs would work as well, might make it a bit tough to pull anything though., it's already got pretty tall axles.
Synthetic gear lube in the diffs will help with the fuel mileage
aswell as the gear boxes .

Synthetic in the engine is only a wise choice if your engine doesn't eat oil. If you have a sound engine, then yes, by all means, swithc to synthetic and put a bypass filter on it. you will get reduced friction, better fuel mileage , and much longer between changes. if your engine eats oil, you'd be wasting your money.

i know that they have a zero cool factor, but tall narrow tires with a rib highway tread will give you the best fuel mileage ( ask any truck company ) mud tires can eat 2 or more MPG just pumping air ( says the guy with 4 mud tires on the back of his dually this will have to do til I can get a winch stout enough to pull truck and 5er on front of truck )

Those air seperating fuel gadgets are for modern ultra high pressure electronic injection diesels that have injectors that are triggered by computeres to fire off a number of times for each piston stroke, they prevent dry pulses. That type of contraption would have no effect on our old mechanical injection systems.

Might want to hold off on intercoolers and such. those a fun thing to have, but won't do much to help with fuel mileage. Making sure your injectors spray test out ok is a good idea . a dribbling injector can waste a lot of fuel over time.

Yes, maximum air pressure in the tires will give best fuel mileage. I remember a government official shortly after the 55 speed limit lift admitting that all the fuel supposedly saved by people driving at 55 could have been accomplished by everyone driving the speeds that had been before and increasing the air pressure in their radial tires by 2 psi instead

Hard to say if a wind deflector would work or not. I almost think you'd have to get some heavy rubber and rig a serious ground effect skirt all the way around the thing within about 2" off the ground to effectively do anything about that

---------Robert

 

[The Warden]

I believe the ZF-5 has a .71 OD ratio.

Actually, the ZF's OD gear ratio is 0.77. I have a data sheet for the tranny in .pdf form (too big to attach to this message); PM me your E-mail if you want to take a look (but, best to do it before I leave on Saturday! )

I think that swapping to a ZF is a great idea...however, it may not fit into your budget unless you get lucky and find a good used tranny. I paid $500 for my tranny, $1000 to rebuild it, another $500 or so for a clutch, and a bit over $250 in other miscellaneous parts...the final cost for my tranny swap was just under $2,300. It was a lot of money given my budget at the time, but as a long-term investment, I think it was money well-spent (OTOH, my T-19 was dying, and my buddy's shop was available). With 4.10 gears and mostly highway driving, I went from 12-13 to 16-17 mpg (18-20 on straight freeway runs)...not sure how it would change with 3.54's, but I can only imagine it going up.

I'll be following this thread with great interest; with my truck as my current daily driver, I want to get all the economy I can out of her...

 

[TLBREWER]

One other thing to keep in mind. Make your changes one at a time to reduce variables. Probably run two tanks of fuel thru trying to use the same driving habits to accurately measure the results before making another change.

Tom