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Fuel Economy

Started by SwingOak, May 14, 2008, 10:17:05 PM

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SwingOak

I've been monitoring my fuel consumption since the beginning of January, and I've been averaging 15.2 mpg with my '02 Chevy 2500HD Duramax. I was looking into buying  something to improve fuel economy, such as programmers, ECU swaps, exhaust/air filter/turbo kits etc., and the one thing that just about everyone out there on the internet truck forums says is that driving habits and proper tire inflation help more to improve fuel economy than anything you could bolt on.

So starting a couple of weeks ago, I've been making sure my tires are at full pressure, and checking them every week. I've been driving the speed limit, making easier starts & stops, and paying more attention to my speed and rpm's (for example, if I drive a wee bit over 37 mph the top gear kicks in and the truck pulls along at about 1100 rpm's)

My fuel economy has gone to 17.4, and 18.5 mpg in the last two tanks. And what's more, my driving doesn't include a whole lot of highway miles either.

To put this in perspective, I drive about 22,500 miles per year. So at $4.20 per gallon, that means I'll save about $1000 per year in fuel costs just by changing my driving habits.

:)

jokers

You`re right on the money Lurcherman, no pun intended.

My truck is an 04.5 Ram 3500 SRW CTD auto with an E-Z Dumper insert and 30" sideboards. It weighs 8,000# empty  :o and I`m getting 18 mpg by keeping the tach under 2k while accelerating or tooling down the highway which equates to about 72mph in overdrive. I keep the tires pumped up to 65-70#. How I accelerate is everything!

If I want to jackrabbit at the stop signs my mileage goes down to about 13.5 but every once in a while it`s nice to leave someone in a cloud of black smoke.  ;)  :D

Handy Andy

  Have you heard of "hypermiling"?  Tried it yesterday, and think maybe it works.  Wouldn't work while pulling a load, but in my truck empty, works.  Course I have an old Toyota with a stick shift.  What you do is get to the top of the hill, and kick her into neutral and let her coast.  Restarted using the clutch after starting uphill before losing too much speed.  You have to shut down the engine, or you are burning gas.  
Also find that just driving 40 mph saves gas too.  Jim
My name's Jim, I like wood.

Tom

One of the most important tricks learned by truckers hauling loads is not put yourself in a position of having to use your brakes.   Know a mile ahead of where you are going to turn and coast the last half mile.  Taking your foot off of the excelerator saves fuel. (don't use neutral, you need the control and safety of a running engine)  I guess you could use the clutch if you wanted.   

When you excelerate, don't mash the footfeed anyfurther than it takes to go faster.  Just keep on a steady upwards climb.

People in sports cars behind you might get upset, but ... So what?

jokers

Quote from: Handy Andy on May 14, 2008, 10:46:15 PM
 Have you heard of "hypermiling"?  Tried it yesterday, and think maybe it works.  Wouldn't work while pulling a load, but in my truck empty, works.  Course I have an old Toyota with a stick shift.  What you do is get to the top of the hill, and kick her into neutral and let her coast.  Restarted using the clutch after starting uphill before losing too much speed.  You have to shut down the engine, or you are burning gas.  
Also find that just driving 40 mph saves gas too.  Jim
In many states this is illegal, as Tom states you are not in control of the vehicle if it is moving while not in gear. It`s an automatic failure in NYS on the CDL test. More food for thought if you are driving a commercial vehicle or are commercially licensed, not that I endorse it for anyone.

sawguy21

Tom makes a good point about the brakes. In driving competitions, truckers lose points if they touch the brakes before the last few feet of a complete stop. Of course they have engine retarders.
I have noticed mileage drops substantially if I start pushing over 100km per hour (just over 60). I also stay back in traffic and plan ahead for turns, sure reduces wear and tear on the truck.
old age and treachery will always overcome youth and enthusiasm

DouginUtah

Quote from: Tom on May 14, 2008, 10:58:50 PM
(don't use neutral, you need the control and safety of a running engine)

Huh? ???

Just being the contrarian....

What control and safety do you not have when in neutral? Can't you be in neutral and still have a running engine?

Oh, you are talking about a semi-truck, not my automatic car.

Never mind.  ;D
-Doug
When you hang around with good people, good things happen. -Darrell Waltrip

There is no need to say 'unleaded regular gas'. It's all unleaded. Just say 'regular gas'. It's not the 70s anymore. (At least that's what my wife tells me.)

---

Tom

 :D You old Contrapuntist!   :D :D

ScottAR

I've found if I keep my powerstroke under 2k rpm my mileage is much
better.  I also practice progressive shifting when I think to do it. 
Scott
"There is much that I need to do, even more that I want to do, and even less that I can do."
[Magicman]

kenneth

I have found that I save a lot of fuel by not letting my rig warm up as long. I put it in neutral every chance that I get, I keep the tires inflated a little over, and I never rev it over 2K. It brought my milage up.

submarinesailor

Back when I was a young man, I was taught that it was bad for your automatic transmission if you put it neutral and coasted down a hill.  Is this still true with the newer ones?  Can I put it neutral, keeping the motor running for brakes and steering, coast down a hill, and put it back in gear when I need too?

Bruce

Ron Wenrich

I've been running a hydrogen boost for the past month.  I've increased my milage about 15-20% without too much difference in my driving habits.  I'm still toying with the unit and the setup.  Some of these are way over priced and some just don't seem like they would perform very well.  

I also run a scan guage to monitor milage, rpm, fuel consumption and the like.  My worst milage is running in the morning when the air is cool, and running on the interstate.  My best is an afternoon drive to town on a rolling hillside and not too many stops.  Difference is about 50% between the two.  Red lights and stop signs really drag down the milage.

The gas station that I go to has now put in E-10 gas - 10% alcohol.  So far, I haven't noticed a lower milage, but its only been a few days.
Never under estimate the power of stupid people in large groups.

RSteiner

Tires can make a big difference in fuel economy, both if they are under inflated or wide.  The rolling resistance of the tire goes up the wider they are and if under inflated.  I have toyed with the idea of changing the tires on my Toyota from 15" to 16" rims and using a tire with an aspect ratio of 85 instead of 75 with a tread width one size down.  The difference in reveloutions per mile is something like 720 reveloutions for the 15" with an aspect ratio of 75 and 665 reveloutions for the 16" with an aspect ratio of 85. 

As far as coasting without the engine running I can say it is not a good idea.  When I was in high school during one summer vacation I drove a rubbish truck.  I was running low on fuel and had a few stops in a rural area up this big hill.  On the way down I thought I could save some fuel by shutting off the engine and coasting down the hill.  Well, I found out quickly that you don't have much for brakes when the engine is not running and the power steering doesn't work so good also.  :o  :o :o

I have gained a couple of MPG by inflating the tires to the correct pressure and adjusting top speed and acceleration.  I enjoy the drive a lot more but tend to irritate the speeder behind me.  ;D

Randy
Randy

SwingOak

That used to be called "Colorado overdrive". I did that all the time when I drove a car with manual steering and brakes. With my truck, if I am doing 40 mph or less, the rpm's drop to idle when coasting. At higher speeds, the idle speed is higher too, but not much.

Vehicles these days have intelligent fuel management systems, and they basically shut off the fuel if there is no load and you are coasting, so shutting the engine off, beside being dangerous, won't help much.

Also, I had bumped my truck into neutral once while going down hill, and the RPM's went way up. When I put it back in gear, it slammed in so hard it scared me. I won't be doing that again, I can tell you.

jokers

I`m not going to claim to be an expert on why it`s a bad idea to coast in neutral as long as the engine is running, someone somewhere along the line told me the logic is that a vehicle is considered unable to power it`s way through evasive manuevers if necessary, but I can`t even remember who, so that`s just anecdotal. That being said, assuming that there is absolutely no risk of accidentally shutting down your engine, locking your steering while in motion  :o loosing power steering or braking, or the ability to quickly and seamlessly get your vehicle back into a suitable gear range without over revving or otherwise damaging your tranny, how much has your fuel economy improved since starting to hypermile? This question is open to any and all of it`s proponents.

jokers

Quote from: submarinesailor on May 15, 2008, 05:50:04 AM
Back when I was a young man, I was taught that it was bad for your automatic transmission if you put it neutral and coasted down a hill.  Is this still true with the newer ones?  Can I put it neutral, keeping the motor running for brakes and steering, coast down a hill, and put it back in gear when I need too?

Bruce

From towing a vehicle behind the RV I have been informed that many autos have an oil pump that is not driven unless the tranny is in gear, consequently why so many are towed on dollies versus flat towed. You can buy auxiliary transmission oil pumps for those vehicles that must be flat towed. This is also anecdotal information because it`s simply an account of my experience and I don`t claim to know if it`s universally true.

jokers

Quote from: ScottAR on May 15, 2008, 03:30:58 AM
I've found if I keep my powerstroke under 2k rpm my mileage is much
better.  I also practice progressive shifting when I think to do it. 
2k does seem to be a sweet spot for many engines, gas or diesel.

What exactly is progressive shifting?

pineywoods

Quote from: jokers on May 15, 2008, 09:29:43 AM
Quote from: submarinesailor on May 15, 2008, 05:50:04 AM
Back when I was a young man, I was taught that it was bad for your automatic transmission if you put it neutral and coasted down a hill.  Is this still true with the newer ones?  Can I put it neutral, keeping the motor running for brakes and steering, coast down a hill, and put it back in gear when I need too?

Bruce

From towing a vehicle behind the RV I have been informed that many autos have an oil pump that is not driven unless the tranny is in gear, consequently why so many are towed on dollies versus flat towed. You can buy auxiliary transmission oil pumps for those vehicles that must be flat towed. This is also anecdotal information because it`s simply an account of my experience and I don`t claim to know if it`s universally true.

Almost all automatic trannys have an oil pump that is driven off the input shaft. If the motor ain't running, the tranny gets NO lubrication. There are a couple of exceptions. Some older hondas and most saturns will lube with the motor not running and in neutral. Some manual types will survive, some will sieze up, usually the reverse idler gear overheats and dies. When you see a vehicle being flat towed behind an RV, it will be 4 wheel drive, put the transfer case in neutral and the tranny doesn't turn.

Back to the original subject, coasting down a hill with the tranny in neutral and the motor idling...not a good idea for several reasons. Power steering and most power brakes are running at reduced capacity with the motor at idle speed. If the motor dies, you gonna be in deep trouble. In reality, you may be using MORE fuel by doing this. yeah, less used going down the hill, but when you tromp on the pedal to start up the next hill, the accelerator pump in the carb pumps a stream of raw fuel down the intake, most of it turned into black smoke out the tailpipe.
OK, computer controlled fuel injection is a whole nother story, but the same reason still apply.
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

flip

Proper tire inflation (or slight over inflation), proper alignment, good air and fuel filters, good fuel (stay away from the E10, E15 and E85 stuff) if possible.  Letting your foot off the gas and coasting in gear is OK going down hill.  Controlling starts and stops and limiting short trips like previously mentioned is best.  Most of your fuel economy or lack of is directly related to fuel and your driving habits. 
When we hit $4.00/gal we will again get calls with complaints in fuel econ. (3-4mpg) and they don't like it when I tell them there is nothing we can do. 
Timberking B-20, Hydraulics make me board quick

pigman

Quote from: flip on May 15, 2008, 11:43:45 AM
When we hit $4.00/gal we will again get calls with complaints in fuel econ. (3-4mpg) and they don't like it when I tell them there is nothing we can do. 
Flip, are you expecting the price to go down!  Diesel was $4.30 in town this morning. :o 
Things turn out best for people who make the best of how things turn out.

beenthere

Quote from: Lurcherman on May 15, 2008, 08:47:46 AM
..................................
Also, I had bumped my truck into neutral once while going down hill, and the RPM's went way up. When I put it back in gear, it slammed in so hard it scared me. I won't be doing that again, I can tell you.

Prolly had the cruise control on when ya bumped it into neutral, and the engine was trying to bring the truck back up to set speed.  I've done that too. Not on purpose, but bumping the stick.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

flip

No, but every time it goes up .20 the phones start ringing and the howling begins again.  They always get 25 mpg and now since the price went up they only get 23 ::) and what am I and Ford going to do about it.  My general response, "Is the check engine light on?  Is it running bad? No??  Sorry, there is nothing I can do.  I get 9mpg in my '01 F250 gas burner and drive to and from work only.  I tell them that and they don't feel so bad about filling up 1 time to my two.  There is a reason why you won't see an estimated fuel mileage tag on the window sticker of a new diesel truck.  If you can afford a $45,000 rig to pull around jet skis you don't need to worry about how to pay for fuel :)
Timberking B-20, Hydraulics make me board quick

Warbird

Quote from: RSteiner on May 15, 2008, 06:45:34 AM
I enjoy the drive a lot more but tend to irritate the speeder behind me.  ;D

Randy

Hey Randy.  You ain't kidding!  It has gotten *really* bad with people being angry at someone for actually driving the speed limit.  They usually tone it right down when they get a good look at 'ol Bessy (my work truck), tho.  She's obviously a workin' truck and when she's got the snow plow hanging off the front end, she demands respect.  ;D

BTW: I thought that the most fuel efficient speed was 55 mph?

Warbird

Quote from: flip on May 15, 2008, 01:46:59 PMIf you can afford a $45,000 rig to pull around jet skis you don't need to worry about how to pay for fuel :)

The problem is those folks doing this are driving up the prices for all the rest of us.  :(  And what's worse is I think a bunch of them are doing it on credit.

flip

The one's that buy the high $$ rigs are in two classes-the ones that need em for legitimate work reasons and those that are spoiled rotten and have to out do the neighbors.  I have seen both of these types buy straight out because they have the $$ to do so and those that try to make due with a $900/mo payment because they can't control themselves. 
We had a guy with a plumbing business bring a truck in last week for some front end work, he ok'd $2500 in steering and brake work, while he was here he bought a new work truck and car for the wife, didn't test drive either vehicle, wrote a check and took along that day.  2 man plumbing operation, think he bought with savings or home equity loan ???

Soccer mom with 3 kids needs a car or van, not a diesel Excursion ::)  I expect to see the trade in lot full of trucks and suvs soon and a lot of focus, fusions and taurus in delivery row ;D
Timberking B-20, Hydraulics make me board quick

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