Fuel efficiency improvements

[ERIC95TAHOE]

i see your point about the 4 door 2 door deal. maybe it was perfect conditions. The only time i could ever see getting a constant 18mpg (like i was guessing with mine). flat road, long drive, no head wind. any more then 18mpg id have to say add a 70mph tail wind

 

[Stresst]

What speed do you think is the best for best mpg?

 

[ERIC95TAHOE]

around here most highway speed limits are 55 so i don't go over 60 much. i haven't noticed much of a difference driving 55-60 compared to 65-70 these trucks are what they are. big, heavy, not very fuel efficient and that is what it is and you can't change it. I have been driving nothing but trucks and big body v8 cars so i am use to crappy fuel mileage and learned to live with it. that is just what i choose.

 

[99Yuk]

What im thinking is there truck's come with differant gear ratio's because there is no way, YEAH NO WAY the same truck's can have almost a 7 mpg differance. JMHO

At 55mph how many rpm's are you cruising at? I will check mine and post back tomorrow. Im sure if I put 3.08 gears in mine I can get 20+MPG!

I have 3.42 gears, stock rims and correct sized tires.
I checked this morning and on a flat level highway at 105kph(65mph) I was running 1655 rpms at ~9% tps.


I do think that these trucks came with different gear ratios in them. I"ve read other guys here say they have 3.72's OEM.

---------- Post added at 04:53 PM ---------- Previous post was at 04:51 PM ----------

around here most highway speed limits are 55 so i don't go over 60 much. i haven't noticed much of a difference driving 55-60 compared to 65-70 these trucks are what they are. big, heavy, not very fuel efficient and that is what it is and you can't change it. I have been driving nothing but trucks and big body v8 cars so i am use to crappy fuel mileage and learned to live with it. that is just what i choose.

+1 I've learnt to live with it, but I sometimes try to match Atis!

I do know that at 120kph(75mph), I'm usually running somewhere around 1900rpm.

---------- Post added at 04:56 PM ---------- Previous post was at 04:53 PM ----------

What speed do you think is the best for best mpg?

I remember waaay back when I was in high school in a physics class and an instructor told us that a study was done and 90kph(55mph) was determined to be the most fuel effcient speed to drive at. Anything faster would consume too much fuel vs the time saved in arriving sooner. Conversly anything slower would consume more fuel as it would take longer to arrive. IDK that was a couple of decades ago though.

---------- Post added at 04:57 PM ---------- Previous post was at 04:56 PM ----------

I coast to stops....only break if and when I need to...

+1

It's all about the coasting. If your chasing mpg, then coast along.

 

[atis]

OK, let me answer several questions to clear things up as I hate the fact that I have started a war over mpg:

1) Tahoe Limited's are all 4 door, 2wd, barn door backs, no 3rd row, 5.7L so that basically places me close to what you all are driving.
2) At 60mph I was turning 1650 rpms this morning on the way to work
3) I am running the stock rims and correct tire size. (but I have the rare 5 star looking stock rims that only came on the Limited...I think they are 15")

OK the only mods I have are in my signature plus the upgrade spider. I have 35psi in all the tires, I have street tires not the mud slinging tires some of you are running so no nobbie noise as they slap the pavement going down the freeway. I rebuilt the rear end last summer (repalced all the bearings and the U joints), replaced the motor in Jan of this year, and just replaced the tranny the first week of April...so basically I have a new truck.

I average 17.7 - 18.4mpg....I dont race off any lines, I brake easy, coast to lights and stop signs, dont follow too close so I dont have to play the on the gas/on the brakes game because the idiot in front of me dropped a Mikey D's fry in his lap.

I pulled the 19.4mpg on a 300 mile freeway trip with 2 adults, 1 kid, and a bunch of soccer gear in the back. I was impressed and can only assume this means the tranny has finally loosened up and settled in to my driving style.


As for the Mustnag question... I have a 91 LX (306, NA, trick flow everything, 3:55's, elect fan, all the bolt ons.... a 06 GT with no engine mods but lowered and a few other little things (all my mod money went to keeping the Hoe alive)... my wife has a 00 GT Vert, lowered, CAI, UD's.

 

[cttandy]

But maybe your truck does get it, can you tell me what im doing wrong? What can I do or buy to improve mileage? My truck has a new fuel pump, filter, air filter and complete tune-up all no more then 8k miles.

Without riding in your truck or watching you drive there is little I can offer you past what I have already mentioned.

My 97 Tahoe was a 4 dr 4x4 with 3.42's. It was 100% bone stock. It was in good tune up. Washed and waxed weekly. 16 city/ 19 hwy was no issue.

Things to consider are climate and altitude where you live. I moved to PA, and even after my truck adjusted to the difference in altitude it never seemed to do the same. But, there was far more city driving in PA then there is for me here in TN, so you have to account for that as well. Roads here are curvy, but no where near so as they were in PA. In fact, comparing the 2, the roads seem straight here. So even the roads can come into play.

I have heard that the road surface can have an effect on your mileage just like the tread pattern of your tires. I have never tried to verify that. Most road surfaces here are the asphalt made with old car tires, and the roads in PA were concrete. I would think the concrete would be the better of the 2 but who knows.

I would recommend going through the wheel bearings and such. Make sure they are all in good condition and not dragging.

Are you running an all season street tire, passenger or a LT truck tire.

Have you seafoamed the truck recently.

Are the plugs properly gapped?

What weight oil are you running? Yes, it really does matter.

Have you cleaned your MAF recently?

What condition are to catalytic convertors in?

What condition is the rest of the exhuast?

What condition is your fan clutch in?

Does your a/c compressor, P/S pump, or ALT have excessive drag due to wear?

When was your alignment done last?

What condition is your steering components?

Do your brakes drag any if you free spin the wheels when the truck is lifted of the ground?

What temp thermostat are you running?

WHAT IS THE CONDITION OF YOUR IGNITION COIL?

What dead weight are carrying around with you?

Little things add up. One or two things might only add up to .05 MPG, but multiple things can really add up.

My 97 was in superb shape all over. The guy I got it from worked in a performance shop and had gone through it for good measure and replaced virtually every normal maintenance item any one would normally go through. I gave it a tune up, and changed the oil. I owned it for 6 months and put 14,000 miles on it during that time. I had plenty of interstate time in it and religiously checked my mileage.

 

[Stresst]

Without riding in your truck or watching you drive there is little I can offer you past what I have already mentioned.

My 97 Tahoe was a 4 dr 4x4 with 3.42's. It was 100% bone stock. It was in good tune up. Washed and waxed weekly. 16 city/ 19 hwy was no issue.

Things to consider are climate and altitude where you live. I moved to PA, and even after my truck adjusted to the difference in altitude it never seemed to do the same. But, there was far more city driving in PA then there is for me here in TN, so you have to account for that as well. Roads here are curvy, but no where near so as they were in PA. In fact, comparing the 2, the roads seem straight here. So even the roads can come into play.

I have heard that the road surface can have an effect on your mileage just like the tread pattern of your tires. I have never tried to verify that. Most road surfaces here are the asphalt made with old car tires, and the roads in PA were concrete. I would think the concrete would be the better of the 2 but who knows.

I would recommend going through the wheel bearings and such. Make sure they are all in good condition and not dragging.

Are you running an all season street tire, passenger or a LT truck tire.

Have you seafoamed the truck recently.

Are the plugs properly gapped?

What weight oil are you running? Yes, it really does matter.

Have you cleaned your MAF recently?

What condition are to catalytic convertors in?

What condition is the rest of the exhuast?

What condition is your fan clutch in?

Does your a/c compressor, P/S pump, or ALT have excessive drag due to wear?

When was your alignment done last?

What condition is your steering components?

Do your brakes drag any if you free spin the wheels when the truck is lifted of the ground?

What temp thermostat are you running?

WHAT IS THE CONDITION OF YOUR IGNITION COIL?

What dead weight are carrying around with you?

Little things add up. One or two things might only add up to .05 MPG, but multiple things can really add up.

My 97 was in superb shape all over. The guy I got it from worked in a performance shop and had gone through it for good measure and replaced virtually every normal maintenance item any one would normally go through. I gave it a tune up, and changed the oil. I owned it for 6 months and put 14,000 miles on it during that time. I had plenty of interstate time in it and religiously checked my mileage.

WOW! Ok! you definetely gave me a thing or to think about. LOL

 

[ERIC95TAHOE]

what about condition of your differential fluid, fuel filter

 

[cttandy]

That is a factor as well. There are websites devoted to see how much mileage they can get out of a vehicle. You wouldn't believe the stuff they recommend.

 

[SunlitComet]

and they are....

 

[ERIC95TAHOE]

and they are....

x2

 

[jthebigjay]

Wow.. i looked here for some advice to improve my 17-18 mpg. Looks like i'm about topped out.

 

[cttandy]

Wow.. i looked here for some advice to improve my 17-18 mpg. Looks like i'm about topped out.

Year/model?

 

[jthebigjay]

99 LT, 4dr, 5.7, 3.43 *or 3.42* 4l60, 148k miles, rear AC, leather.
Stock everything. Just got it about a month ago because it had new front tires.

New water pump, radiator, thermostat, plugs, fuel filter, plugs, dizzy cap and rotor, lower intake gasket set, rebuilt the rear end with new pinion bearings and crush sleeve with Morrie's in the rear, ac compressor, drier, orifice tube, seat leathers, windshield, inside door handles, turned rotors, new brakes, and radio fade and balance knobs...

And i'm still only in the whole rig for under $3000. The body is in PERFECT condition. I practically stole it from the PO because i could rebuild the rear end and AC system my self.

I was hoping to get some advice on getting as much as i could out of this 5.7 MPG wise with measurable results that have a pretty quick return on investment..

If i'm getting 18 mpg now at $3.75 a gallon then i'm paying $.208 a mile.

Say a cold air intake and dual exhaust cost me $400, and my MPG only improves at high end of 20%.

That would move it up to 21.6 mpg ending up at .173 a mile

I would only have to drive about 2400 miles to break even on getting the upgrade.

At the way my wife drives of about 1 tank a week, 27 gallons would get me 486 miles on the old setup at $101.25

The same 27 gallons would get me 583 miles on the same $101.25 on the new setup.

Thats $20.25 a week savings on gas per mpg.

It would take me 20 weeks to recoup the cost of the upgrade.

Is it worth laying out that cash when i will only see a return of that money after 6 months?

Maybe my math is off.

So "is chipping the motor or electric fans or cold air or a Magnaflow cat back WORTH it?"

Just curious............. Its hard to find out for sure..

---------- Post added at 08:19 PM ---------- Previous post was at 08:15 PM ----------

---------- Post added at 09:19 PM ---------- Previous post was at 08:19 PM ----------

I guess you have to find the break over point, or return on investment

Cost of improvements / (((Old cost per mile X Miles per tank) X Miles driven a week) - ((New cost per mile X Miles per tank) x Miles driven a week)) = Weeks to break even.

y = Cost of improvments
a = Old cost per mile
b = Gallons per tank
c = Miles driven a week
d = New cost per mile
z = Weeks to break even

y / (((a X b) x c) -((d x b) x c)) = z

I think.... right?

 

[cttandy]

You can always do what I did and try to do some horse trading for parts.

Realistically, change out the muffler for something that flows better. Cold air intake would be beneficial. Electric cooling fans are worth while in my experience.

As far as the chip or programmer, I wouldn't buy a handheld. Get someone to create a tune for you. Their are many that will do it, I think some are even sponsors here.

The less you invest, the better off you are. I did the home work on my current build, and it has paid off. I did as much horse trading as possible. I have invested around $500 and brought my mileage 17 up to 23. My goal is 25 before I stop.

 

[SunlitComet]

and again those websites are.....?

 

[cttandy]

If you get on performancetrucks.net and ask for tuner advice on your particular truck, you will get plenty of responses of who and why. You will likely find someone near you that could possibly tune your truck in person, that would be the best route.

 

[billiam7787]

hey, just did a cross country trip in my 98 2dr tahoe pulling about 4500 lbs and got 15.3 mpg. total weight was 9,317 lbs (i did a dity move, so i had to go to a weigh station) and i even kept all of my gas receipts. and the kicker....it has 247k miles on an original engine and tranny.

 

[DTAILS]

At time of purchase:

Tahoe bone stock = At best 340 miles per tank w/ 87 octane
260 when pulling a 2500lb trailer 5 days per week

After a few changes including ....
aFe intake
Flowmaster cat-back exhaust
Black Bear Performance tune
Mid Grade fuel rather than the low end (now using 89 octane)
Full synthetic RP oil (yes, it makes a difference with the Tahoe as well as my BMW and 4Runner)

475 - 490 miles to the tank when not pulling a trailer
365 - 380 miles to the tank when pulling a trailer

All in all, the tune along with upping the octane to mid grade made the biggest improvement.

 

[atis]

Billiam,

what mods do you have??