Diesel Place banner

1 - 20 of 47 Posts

·
Registered
Joined
·
186 Posts
Discussion Starter #1
I am just curious, what kind of fuel mileage is everyone getting with there 6.2.
I just sold a 85 chevy dually with a 6.2 and a 4 speed and it was getting 17 mpg with everyday driving.
I am concidering doing a project to see if i can get 25 mpg with a 6.2 in a 82 shevy swb with a 700r trans.
 

·
Registered
Joined
·
3,964 Posts
I have had a few 6.2 trucks over the years. The best I've ever seen has been 30mpg. I know it sounds high.....but that was with my 92 chevy ext. cab 4x4. I would always see 22-24 out of it. Mind you I'm talkin Canadian gallons.

My 6.5 turbo isn't as good........but waaaaay better power and better cooling while towing.

Just my 5 cents.
 

·
Registered
Joined
·
186 Posts
Discussion Starter #3
mileage

That is encourging, i thought 25 was ambitious. I am mainly after a daily driver.
I am not really a fan of the new trucks and i have a 42 mile commute one way.That is why i am concidering this project, I already have all of the parts, it is just a matter of putting everything together.
 

·
Registered
Joined
·
3,964 Posts
Are you pulling anything? If you are, the 6.2 may be under powered.
I used my 6.2 for my daily driver/commuter truck.
The one thing I'll give the 6.2 is the economy..........and I think they sound nice (that may be two things...)
 

·
Registered
Joined
·
97 Posts
Well I for one don't think it gets ANY better as far as fuel milage than the 6.2l I had one in an 83' two wheel drive one ton with a turbo 400 and a 4:10 gear that got around 20 mpg. And my current truck is an 84' k-10 that also gets around 20mpg with NO mods yet :)

Now I do think there are some things you need to be aware of with this wounderful engine, and that is it IS ADDICTIVE at least for me it is.

The sky is the limit as far as just what you want to do to make it truly economical, from just air flow mods to full on WVO systems but it sounds like it could be a great project for you IMHO.

Most importantly HAVE FUN WITH IT! ! ! !


Chuck
 

·
Registered
Joined
·
2,597 Posts
since its just gonna be a daily driver look into getting some high gears. 3.08 would be a good choice, somebody on here has even higher gears in a parts truck of theirs, i think 2.73'ish.

dont lift it, keep it at stock height. free flowing air intake, dual 2.5" exhaust, should easily get 23-25 mpg, higher is possible.
 

·
Registered
Joined
·
109 Posts
I've never done combined mileage check on mine. It will be a lot less than what i get on the hiway. I will get consistantly 30-31mpg (Cdn) at 70-75mph. We use it on long trips partly because it gets better mileage than my wifes 2 previous vehicles, 2002 Mazda Tribute and 99 Pontiac GTP. We will see what her 2004 Nissan Murano gets. I suspect the old 6.2 will still be the economical one.

Gerald
 

·
Registered
Joined
·
1,119 Posts
I filled up the other day and figured about 18.6mpg with a bit of everything. Around town, highway driving, and 4 hours of offroading. The 3.08 gears help but Im going to be moving to 3.54s or something lower for offroading and bigger tires.
 

·
Registered
Joined
·
186 Posts
Discussion Starter #9
truck

I will not be pulling my trailer very often with this truck.I have a 86 k 20 for that.
This thuck has a 3:42 gear and i will be using a 700r4. I actually am going to lower it a little bit, i forgot to mention it is a 2 wheel drive.
I think it will be a neet project, yhis is completely opposite from what i usually do. I usually pull the 6.2 out and put in a gas motor.
Heck at one time i had 8 350 diesel motors laying behind the barn, I did convert one of them back to gas and that was one stout motor and the rest went to the junk yard.
 

·
Registered
Joined
·
2,315 Posts
JKC;1570638; said:
That is encourging, i thought 25 was ambitious. I am mainly after a daily driver.
I am not really a fan of the new trucks and i have a 42 mile commute one way.That is why i am concidering this project, I already have all of the parts, it is just a matter of putting everything together.
30 miles per Canadian gallon is 25 miles per U.S. gallon. That's about the top limit for a low, 1/2 ton 2WD Suburban with 3.08 axles, stock tires, and overdrive. You might hear reports of 25 city driving and 30 MPG highway. Believe it when you see it - and I doubt you ever will.

Higher and heavier 3/4 4WD Suburbans - besides having more wind-resistance - they are usually geared differently and often have no overdrive. 3.73 axles are the most common as well as the TH400 automatic transmission. My 87 and 89 Suburbans - both 3/4 ton, 3.73 axles, and TH400 trans. - both get 13 MPG around down and a best of 19 MPG on the highway. At high altitudes, e.g. 5000 feet, highway mileage drops to around 17 MPG. MY 1991 1/2 ton, 4WD Suburban with 6.2 diesel and 3.42 axles has gotten a best of 21 MPG so far - on a long flat highway run - but it might do better in the summer - so far I've only done winter driving with it.
 

·
Registered
Joined
·
3,149 Posts
I have a, just look at the sig.
It gets 15-17 in the city, up to 20. 20MPG in the city was a one time thing, so far.
On the high way I get about 24mpg. But I have not taken it on the high way since I changed the main and connecting rod bearing and switched over to synthetic oil.
 

·
Registered
Joined
·
6,412 Posts
I usually get 26-27 mpg (US) driving to work. This week it was 24... A little lower than usual, but that included lots of idleing because it is so cold outside that I didn't want to shut it off very often. Last week and the week before that it worked out to ~26 mpg.

You should be able to get 25 mpg easily if you ask me...

By the way, pulling a 350 diesel is different than pulling a 6.2... The main difference is that nobody wants the 350 diesel... ):h That said, I have a 350 diesel which I am building up with plans to install it in an S-10 or S-10 Blazer (although I might install it in something else - I was considering a late '60s muscle car for a while). I'm expecting power pretty similar to the 4.3 V6 gasser that the S-10 came with and probably 30-35 mpg or better... :cool2:
 

·
Registered
Joined
·
454 Posts
So how come I'm only getting 13, with new injector nozzles, 3.42gears? th400 trans. i'd love to get 18.
 

·
Registered
Joined
·
2,315 Posts
4DR4X4;1574257; said:
So how come I'm only getting 13, with new injector nozzles, 3.42gears? th400 trans. i'd love to get 18.
I didn't think they made them with 3.42 axles - is that original? I had a military crew-cab a few years ago and it had 4.10 axles and the TH400 trans (3L80). It was too long and turned too wide for my uses. It also seemed to have a very heavy frame. Mileage around town was 12-13 MPG and on the highway - never faster than 65 MPH was around 16-17 MPG at best. Are use sure about the axle ratios? If so, it ought to do a little better on the highway. Is the tailpipe full of black soot or is it relatively clean.
 

·
Registered
Joined
·
6,412 Posts
4DR4X4;1574257; said:
So how come I'm only getting 13, with new injector nozzles, 3.42gears? th400 trans. i'd love to get 18.
How old is your injection pump? Also, is this city, highway, or combined?

Also, don't ignore the possibility of a fuel leak of some sort. My gas mileage was dropping drastically a while back and I couldn't figure out why... Then I realized one of my return lines was leaking. Fixed it and it's back to normal...
 

·
Registered
Joined
·
269 Posts
i average between 20 and 25 in the city depending on time of day and on the freeway at 75 which is where i have her geared i get between 28 and 31 depending on the grades i am running a 2004r that has a od ratio of .67:1 and my dif is a 3.08

i a not a lead foot but i believe it has a lot with induction as well i am basically running 2x 3.5 inch hard pipe straight from the front of the grill with 2 intakes 1 on each side and i have built a top hat for the intake manifold where i piped them through a set of ford round air filters which are now k&n they came off a 02 f150

the pipes are insulated as well too help keep as much heat out of the intake tract as possible

but cruising at 75 i turn around 1700 rpm give or take 50 lol and shedoesjust peachy

another thing that might have some to do with it is that my truck is relatively low to the ground the front cross member just below the oil pan sets about 4 inches off the ground and the rear wheels are tucked pretty good as well imo it helps a ton with wind resistance which is a major role in increasing fuel economy
 

·
Registered
Joined
·
6,412 Posts
average between 20 and 25 in the city depending on time of day and on the freeway at 75 which is where i have her geared i get between 28 and 31 depending on the grades i am running a 2004r that has a od ratio of .67:1 and my dif is a 3.08

i a not a lead foot but i believe it has a lot with induction as well i am basically running 2x 3.5 inch hard pipe straight from the front of the grill with 2 intakes 1 on each side and i have built a top hat for the intake manifold where i piped them through a set of ford round air filters which are now k&n they came off a 02 f150

the pipes are insulated as well too help keep as much heat out of the intake tract as possible

but cruising at 75 i turn around 1700 rpm give or take 50 lol and shedoesjust peachy

another thing that might have some to do with it is that my truck is relatively low to the ground the front cross member just below the oil pan sets about 4 inches off the ground and the rear wheels are tucked pretty good as well imo it helps a ton with wind resistance which is a major role in increasing fuel economy
That is very impressive! :cool2:
 

·
Registered
Joined
·
454 Posts
jdemaris;1574431; said:
I didn't think they made them with 3.42 axles - is that original? I had a military crew-cab a few years ago and it had 4.10 axles and the TH400 trans (3L80). It was too long and turned too wide for my uses. It also seemed to have a very heavy frame. Mileage around town was 12-13 MPG and on the highway - never faster than 65 MPH was around 16-17 MPG at best. Are use sure about the axle ratios? If so, it ought to do a little better on the highway. Is the tailpipe full of black soot or is it relatively clean.
4.10 is stock, iv'e swapped the rear for a 3.42, and yes, the speedometer is dialed in perfect. :cool: the frame and bed have also been shortened 30 inches. it wieghs 6100 lbs. the injection pump is the stock one for the 85 military 6.2 engine in it, turned up 1/4 for the turbo. I'm thinking its getting tired.
 

·
Registered
Joined
·
6,412 Posts
the injection pump is the stock one for the 85 military 6.2 engine in it, turned up 1/4 for the turbo. I'm thinking its getting tired.
That would be my guess as well as long as there are no fuel leaks.
 

·
Registered
Joined
·
2,315 Posts
4DR4X4;1575383; said:
4.10 is stock, iv'e swapped the rear for a 3.42, and yes, the speedometer is dialed in perfect. :cool: the frame and bed have also been shortened 30 inches. it wieghs 6100 lbs. the injection pump is the stock one for the 85 military 6.2 engine in it, turned up 1/4 for the turbo. I'm thinking its getting tired.
There are two basic things the injection pump can do wrong - pump too much fuel or not advance the timing properly. The first thing to wear on that pump is the timing advance- it rarely will work properly after 100K miles - but goes slowly.

A 6000 lb. truck with 3.42 axles ought to be capable of 18-19 MPG on a flat highway run and 13 MPG around town driving - unless you've changed the heads to the newer 6.5s and larger precombustion chambers.
 
1 - 20 of 47 Posts
Top