Vacation MPG

[Andy Chesek]

Just returned today from a trip to Frisco, NC, in the Outer Banks, and I thought I'd share my MPG info. This is my first long trip since the intercooler was installed. As ugly as it put in, it must work.

Distance from home to said location was a hair over 450 miles. On the trip down I managed 22.44 mpg. This was maintaining cruising speeds between 62-72 mph, where applicable, but mostly in the 62-67 mph range. Fuel came from my home area Hess station, where I pretty much always fill up.

On the return trip home I averaged 20.74 mpg. I attribute the lower mileage to a heavier right foot on the way back. Traffic was generally going a bit faster, and I found myself going 78 mph at times. I wouldn't go over 78 because I'm pretty sure my tires aren't rated to go faster... Fuel came from a Mobil station. I don't know what people have to say about chain A versus chain B, but others do like to know who bought what where. Also the first time I ever filled up at a Mobil.

Anyhow, I was very happy with the fuel economy I experienced during the trip. I borrowed a cap to put over my bed, and literally had the bed stuffed with gear. Couldn't estimate the weight, but sure made the truck ride soft and easy. Too bad we had crummy weather all week, the truck is about the only good thing to talk about.


Note: In case anyone is wondering if diesel fuel is available in the Outer Banks, the answer is a resounding YES. The majority of stations there do carry diesel, so don't sweat it if you plan on heading down that way.

[tanker]

Great MPG's, I assume you have 3:73 Axle ratio :rolleyes: . Do you add a cetane booster? You could help with addition cetane. Amoco did have the highest cetane at one time, but since BP joined forces with Amoco who knows. I've been buying at the Flying-J in Carmel Church Va. (I-95, mp#104) about as low a price on the I-95 corridor as can be had. I also do by Hess at time back home.
A good additive such as FPPF "Total Power" or "Stanadyne" performance forular will help with lubricity and raise cetane levels, plus control waxing in winter, and disperse water.
I used Stanadyne for years in my 95 suburban, and now use Total Power in my 05 D-Max. smile.gif

[markrinker]

Wow. That is DOUBLE what I would expect to get with either of my 6.5s unloaded. What a (negative) difference 4.10 gears make.

[Andy Chesek]

I did add a little of Power Service's cetane booster (gray bottle, up to +6 points). I try to make sure I add some before I head out on a decent trip, if not more often. I have 3.73's, I didn't mention that in my post because it's in my sig.

I failed to mention in the earlier post that my previous best was 21.5 mpg, and that was pre-intercooled on a 200 mile trip from Coudersport, PA to Dover, PA. So, if I take the difference between the 22.44 and 21.5 I get 0.94 mpg. That extra 0.94 mpg is a 4.37% increase in fuel economy.

I guess my truck's a good runner. I like the manual tranny for situations just like this, but it's starting to shutter when I let the clutch out in first or second gear. I replaced the clutch about 28k miles ago, guess it'll need looked at again. As much as people praise manual trannies for being bullet-proof, it seems like they just bite you a little bit at a time but end up costing the same in the end as an automatic... having to replace clutches every 30 - 50k miles.

[fastcat800]

My truck is all stock except for a cut out in the air cleaner and a cab height topper. Automatic transmission with 3.73 gears at 78 mph on the freeway I got 18.2 mpg and at 68 mph I got 20.2 mpg. This was about a month ago and with cetane additive to boost 3 numbers. I wish I could do better towing my sleds in the winter. Best I got was 12.4 pulling an open four place (4000 lbs) at 65-68 mph on the freeway and usually averaged about 11.5 mpg. I will see how it does this summer pulling my 5500 lb boat up to Lake Superior. I am hoping for 13 mpg.

[ANXIOUS-SUBMAN]

I'm leaving for Avon, NC this Friday. It's about 760 miles from our home in Indiana. I just installed a Gear Vendor a couple weeks ago. Typically on this trip I'll get just a little over 16mpg. If I run around 75 it will drop under 16. I'm anxious to see what improvement in mileage the GV will give me. However, it won't get much action during the part of the trip through the mountains. (It sure cruzes alot quieter) We usually stay in the Duck area or farther north. I've filled up at the Hess station on the bypass during past vacations. I think they had the best price.

I usually run Power Service (Grey bottle) But, sometimes I'll stop at the Flying J in Walton, KY to pickup a bottle of "Meaner Cleaner" They did'nt have it today but had something different. "Liquid Muscle" in a gallon jug for $14.95. Must be new cuz the bottle said their trade mark was not registered yet. I'll have to do a search on the internet and see what I can find out. I went ahead and bought a jug. I figured the gallon jug would be perfect for the trip.

[jspringator]

I don't understand why my mileage is so much worse than everyone else's. The best I have ever gotten was 13.5 and that was a fluke. I usually get around 12.5.I guess I need new injectors.

[GMCHORSHAM]

James, don't beat up on yourself. The variables that determine MPG are great.
My milage ranges from a low of 11.4 mpg to a high
of 17.4 mpg. The interesting aspect was the 17.4 mpg was obtained last Christmas, while pulling 2 horses and a tub full of camping gear and horse tak. I travel at 60mph with this load, and this doesn't vary much.
As I said the variables that determine mpg are
enormous, however the biggest contributing factor in my case has been the gas pedal, hence
11.4 mpg in and around town.
Regards; Rod.

[GMCHORSHAM]

93_Burrito, The mpg that you listed is brilliant.
I have a question on the 30-50K miles for clutch replacement, is this typical ?
The milage sounds a bit low for clutch replacement.
I am not speaking from experience, I am just curious. I have been running auto's for years.
Regards; Rod.

[Andy Chesek]

GMCHORSHAM,

From what I've been reading in numerous threads on this site, there are a few problems that commmonly pop up with manual trannies.

The first clutch in my truck had several cracks and fragmented pieces. When the mechanic got in there to take a look he said the disc practically crumbled apart on him. This happened with 70k miles on the odometer. I had the clutch replaced with a LuK, and the flywheel was turned down.

This shutter problem that's developed now seems to be at its worst when the truck has sat overnight. I couldn't take a guess myself to say what the problem may be. With first gear being a granny, I can let the clutch pedal out and it will take off without hitting the accelerator pedal. If I try to let the clutch pedal out slowly, it will shutter almost like a loping feeling. I have about 98k miles on the truck now.

The first clutch replacement cost over $900, since I don't do bigger jobs like that myself. So, if I have another situation brewing like that and it were to cost me another $900, compare that to an automatic tranny rebuild... adds up pretty quick and to me an automatic is starting to look pretty good given I've got let than 30k miles on the new clutch.

The 4L80E transmission serves many DP members well, so I wouldn't mind having a truck equipped with one. I'll probably sell this truck to get an automatic. Takes care of another issue as well, my vertically challenged girlfriend has trouble reaching all the pedals in my truck so she refuses to drive it.

[moondoggie]

Good Day!

James Springate: I can only parrot what I

[Andy Chesek]

I'm running LT245/75/R16 BFG All-Terrain AT/KO's, which is the same tire size it came with from factory.

[jspringator]

I have stock tires, TDC offset of -1.5. I see about 8 MPG while towing a 33 foot travel trailer. 12.5 is every day driving, around town and 15 mile trips. The PO told me he got 15, but I have never been near that.

[Jim P]

I have a 30' Jayco fifth wheel that is pretty tall(11') and catches alot of wind. I get right at 12 mpg pulling it, doing 65 mph.

I just took a trip to michigan pulling my 16' flat bed trailer that weighs about 2400 lb and got 17.5 mpg on the way up and 16 on the way back. I had two machines on the trailer on the way back that weighed about 1000 lbs together.

I usually get 18 mpg driving to work except in the winter and it drops to about 16.5 with the extended warmups.

[bbudus]

Before my engine went into self destruct mode I was averaging 14-15 in town and 16-17 on the highway/interstate, and I have a severe lead foot so I like to go about 80. The truck was totally stock with 410s.

The best milage I got was a trip to Yellowstone were I got an astounding 26 mpg. All of this out of a bone stock truck. I have not even burned through two tanks yet on my new motor, and have been taking it pretty easy, so those numbers are still coming.

Bbudus

[Dihrdbowti]

In town I get 16 and usually 20-21 when road tripping. I hardly tow and when I did a long trip with a trailer it was 7-7500lbs and I waqs getting just under 16 but I was traveling about 60-65 max. Gears 3.42

[sturgeon-phish]

I just had my best mpg returning to work in Tennessee from Ohio. Mild temp, 60-62 mph, 323 miles, fill up run, fill up, (waiting for dissipation of foaming) 26.2. WOW. Previous mpg usually >20 mpg, but I drive very easy, egg under the foot is my style.

[cldowlen]

No one that I have read seems to take into consideration altitude when figuring mileage.

For three weeks in May I traveled about 7,000 miles. Starting from Las Vegas, NV. to the east coast areas of Virginia, DC, Maryland, West Va. and Pennsylvania. I passed through Arizona, New Mex., Texas, Oklahoma, Ark., Tenn., going there, with a side trip to Dallas, and Missouri, Kansas, Colo. and Utah returning. I achieved between 18 and 23.5 mpg (US Gal.)Driving at about 65 MPH. Total average for the trip was 20 MPG. I observed that mileage above 1500 feet was significantly better than below. My best mileage was 23.5 MPG from Flagstaff, AZ to Grants, NM. This was all above 2000 feet in the mountains. As a check on how speed over 65 mph affected economy I drove 70 mph from the junction of I-70 and I-15 back to Las Vegas and achieved 18 mpg. This was all above 2000 feet and generally down hill. My town driving in Las Vegas varies between 15.5 and 17 mpg

Altidude, speed and distances from my hand held GPS.
--------------
94 Chevy TD Blazer, 4L80E Automatic Trans., 373 rear axel, Computer chip, Phaser Gears, Cooling upgrade, retrofited down pipe, Mr. Kennedy

[JohnC]

Originally posted by cldowlen:
...I observed that mileage above 1500 feet was significantly better than below. My best mileage was 23.5 MPG from Flagstaff, AZ to Grants, NM. This was all above 2000 feet in the mountains...Hmmm, I find the idea that higher altitude contributes to mileage counter-intuitive. It seems to fly in the face of the "more boost is better" crowd, too. At altitude the turbo has to work that much harder to maintain a given manifold pressure.

An aside, I live at about 1600' but burn an awful lot of fuel going up and down the hills to get anywhere... I have to go down 300' and up 100' just to get to my office, 3 miles from home. then it's down 100' and up 300' to get home...

[moondoggie]

Good Day!

[i]

[GMCHORSHAM]

Moondoggie said: Quote; " Ive also found that mpg on one tank of fuel is almost completely useless information."

For any given day we face change! be it Environmental or Emotional. Both impact our mpg at that time.
My view is, whatever mpg you obtain on a tank of fuel, is just that.
"The mpg obtained on that tank of fuel !"
If we have a passion for mpg and accuracy (Eg; moondoggie) the above statement is just, to obtain a mpg mean.
Given the price of Diesel these days, a Diesel mpg SnapShot is Top-Of-Mind, each refill, be it daily or weekly.
Given a Top-of-Mind Snap shot, each tank fill, does effect our Emotional awareness, because it impacts our Back pockets, (disposable income)
especially when we would/could use this money to purchase Engine upgrades or Gearvendor O/D's.
I am not debaiting moondoggie's theories, as his passion for mpg are well documented- written and make good sence.
I am having a sarcastic dig at one sentence.
Keep up the good work Brain, I always enjoy reading your posts, hence I post this knowing that I am walking on egg shells.
Have Fun, Safely.
Rod.

[woodchuck]

My $.02 is this. I have found that when I fill my tank when the punp shuts off, I can consider the tank full, or I can continue filling it and get in up to about 5 gallons more fuel, depending on how patient I am on that day. So how much fule does a full tank have in it? I don't know because I try to never run it empty. Just when is full? That depends. I think the pump, the temp. the phase of the moon, and some random facters all have a contribution. I agree with Brian, it takes an average of several, or better yet many, tankfuls of fuel to have an idea of the actual mpg.

[cldowlen]

In reference to my previous observation about the effect of altitude on fuel consumption I have the following observations and theories.

There is a barometric sensor in the control system for the turbo waste gate. Why, if not to compensate for altitude? At one point in Colorado I was passing, up hill, at an altitude of over 8000 feet and the transmission downshifted briefly, for about 2-3 seconds the boost gauge showed a steady 12 lbs. of boost. This is about 1.5 pounds more than I had ever observed, even when towing.

If you had a carbureted gasoline jetted for Denver it would have to be re-jetted for optimum sea level operation or risk burning valves or pistons because of a too lean fuel/air ratio.

In spite of turbo charging there is a difference in the amount of available oxygen at sea level and 5000 feet. The rule to maintain an optimum fuel air ratio in a computer controlled fuel injected turbo diesel engine should be the same as for a carbureted engine. More oxygen more fuel, less oxygen less fuel.

I spoke to the parts man at my local Chevy dealership and he said my observation was correct. He attributed the fuel economy variation at altitude to emission requirements.

[JD Diesel]

The first clutch replacement cost over $900, since I don't do bigger jobs like that myself. So, if I have another situation brewing like that and it were to cost me another $900, compare that to an automatic tranny rebuild... adds up pretty quick and to me an automatic is starting to look pretty good given I've got let than 30k miles on the new clutch.
I had a f359 4x4 cc I put a kevlar clutch disc in I put 80,000 miles on it when i sold. Best clucth disc I ever had 6.9 Diesel with glass rack average 7 to 9,000 pounds on the truck, think they are worth looooking into.

[Andy Chesek]

JD Diesel,

Do you remember who made your Kevlar clutch? I just did a quick search on Google and came up with a bunch of hits, but I can't say I'm familiar with most sites.

I did like what South Bend had to say about Kevlar clutches, and the many Dodge owners who came to them complaining about the short lifespan of their clutches. I've heard of South Bend before, but I haven't heard of any 6.5'ers using one. Anyone care to chime in?

Drivertain.com offers Kevlar clutches for all sorts of GM engines. What bothers me is the Kevlar clutch they offer for my '99 6.5L requires converting to a dual mass flywheel. Don't know about doing that... In any case, I'm still considering getting another 6.5L truck with a 4L80e tranny, and washing my hands of this. My truck serves me well, and I think they look good.

[moondoggie]

Good Day!

GMCHORSHAM said, [i]