im curious as to what i should expect fuel mileage wise, i got a turbo 400 tranny, 2 wheel drive, regular cab long bed, a rough guess would be nice

What is your rear end ratio and tire diameter?

Currently installing a Banks turbo. Once it is running, I'm going to concentrate on tuning to improve mileage. See below for current specs.

I'm getting about 15mpg, but it's a while ago that I checked --- might be a bit better now. 3.73s, 285/75/16 tires.

I'm getting about 15 mpg as well with the truck in my sig. See below :D

i'm getting 15mpg with a 83 k10 suburban, non-egr manifold, dual 2 1/4" exhaust, 700r4 trans, 31" tires. I'm gonna see what happens once i install my turbo and then make some adjustments where i can.

i'm getting 15mpg with a 83 k10 suburban, non-egr manifold, dual 2 1/4" exhaust, 700r4 trans, 31" tires.

Hm, is it lifted? What's your axle ratio? I'm surprised that you get the same mileage I'm getting --- I was thinking that the lift and the tall tires I have get it down to 15, but you have almost the same truck with smaller tires ...

the tires are 265/70/r16 so about 28 inches tall, im not sure on the rear end, i can find out in the morning

the tires are 265/70/r16 so about 28 inches tall, im not sure on the rear end, i can find out in the morning


probibly 4.11 or 3.73 since it is a 2500

I avg. 17 mpg depending on what I am doing. I have hit 20 once driving it nicely around town. The freeway & Hwy kills my mpgs. If I am heavy on the throttle and run out every gear I get like 14.
I had a stock '90 blazer with a 6.2 w/ egr, 32" tires, and 3.08s and it got 16 pretty consistent.

most of my drive is at 55mph then 70mph on the highway, 60 if im in the slow lane

my 86 4x4 8 lugs 3 speed aut was doing 18-20 315 tires was adding 2 stroke oil help alot w mpg 2-3 more but more powwer on engine litle splash mix on gatorade bottle before dumping it every $40 fiil up for 1 mo and i stoped

Don't mean to jack this thread, but I haven't owned my truck long enough to get an idea of mileage. It's a 78 C-10 with a swapped 6.2, TH400, non EGR manifold. Data sheet says it has a 3.42 posi axle and rolls on 235/75R15 tires.

If someone could give me an idea of what to expect in the terms of mileage please. Thanks guys!

i use a sulfer substitute along with diesel 911, what affect does that have besides cleaning and eliminating the gel factor

0lee,

Yeah, it's the truck listed in my sig. 5" up front, 3" in the rear. 11.00R-16 Michelin XZLs and I only run 25 psi in them with a 700R4 and 4.56 gears. I usually drive about 65 too.

I get 18-20 mpg at 65mph. I have a 400 tranny, 3.73 gears, and 265/75/16's. No mods to the motor. it has about 140,000 miles on it. I don't like to go much faster than 65 due to the high rpm's but there seems to be more power there if I step on it.

i'm getting 16-17 mpg, and in the inter state i do not drive over 65 because my mpg will drop to around 12.

Hm, is it lifted? What's your axle ratio? I'm surprised that you get the same mileage I'm getting --- I was thinking that the lift and the tall tires I have get it down to 15, but you have almost the same truck with smaller tires ...

My Injector return lines have been leaking. I need to replace them tomorrow. Once i do that, i will fill it back up and see what it is then. I'm also gonna rig up an indicator light to see if my tc lockup is working because i can't really tell right now. Hopefully i can get it better than what it is now.

Oh, that might explain it ... Let us know what you get ...

I'm also gonna rig up an indicator light to see if my tc lockup is working because i can't really tell right now.


how are you going to do this...I don't think my tq converter is locking up either and I really don't know how to check if it is or not...thanks for any help.

Chuck.

I get 20+mpg from my 6.2l diesel

have a 1996 k2500 4x4 6.2l, 4l80e

I just got 21.68mpg on a 200 mile trip to the coast, half freeway, half mountain roads and hauling a load of firewood back.

I just got 21.68mpg on a 200 mile trip to the coast, half freeway, half mountain roads and hauling a load of firewood back.

I get about 10-11 on a good day, in a vehicle not much different than yours. Same frame, same engine, but a bit more wind drag, at it's a few inches taller and wider.

I do have new nozzles in there...I'll have to measure it again.

Could it be the TH475, or the 4.10 geared duallies that result in literally one half of your mileage ?

Or maybe it's finally time to replace the IP...

wich get better milleage the egr or non egr? i would asume the non egr and how can i tell if mine is i have a stock 86 k5?

Take the air cleaner lid off, if it has egr, and it probably does, it'll be in the center of the intake opening.

I get about 10-11 on a good day, in a vehicle not much different than yours. Same frame, same engine, but a bit more wind drag, at it's a few inches taller and wider.

I do have new nozzles in there...I'll have to measure it again.

Could it be the TH475, or the 4.10 geared duallies that result in literally one half of your mileage ?

Or maybe it's finally time to replace the IP...
The auto tranny, the 4.10 gears, and duallies are all hurting your mileage. Notice he has a manual tranny with od and as you mentioned less wind drag.

My Injector return lines have been leaking. I need to replace them tomorrow. Once i do that, i will fill it back up and see what it is then. I'm also gonna rig up an indicator light to see if my tc lockup is working because i can't really tell right now. Hopefully i can get it better than what it is now.

I have since repaired the return lines on the injectors. I still got 16.2mpg with the return lines leaking. I will post up my mileage numbers since the repair next week when i fill up.

is there any performance/mileage gain with a non egr manifold and what did they come on?

is there any performance/mileage gain with a non egr manifold and what did they come on?
A non emissions engine (J code) will have more power, and should get slightly better mpgs. There are some minor differences in the two engines, the intake, IP, heads, as well as a valve on the exhaust manifold. The quick way to convert a C code to a J is to replace the intake, and turn the IP up a little bit. A little searching around the forums will return lots of information on the subject so I am keeping this short as to not hijack this thread.

i am pretty sure it is a c engine but where is that c or j code at? actually i know it is becasuase it soes have a egr in the center of the intake, is there a way to blck it off without having to replace the manifold?

i am pretty sure it is a c engine but where is that c or j code at? actually i know it is becasuase it soes have a egr in the center of the intake, is there a way to blck it off without having to replace the manifold?

Check your VIN to see if you are J or C.

You can disconnect the vacuum lines running to it, or buy a set of intake manifold gaskets for a J code. The J code gaskets should have little block off plates in them to block off the passage ways into the manifold. You can also find a J code intake on hummers, and some 3/4 ton, and 1 ton trucks. Check the junkyard. You can look in my garage to see what the J code intake looks like.

The auto tranny, the 4.10 gears, and duallies are all hurting your mileage. Notice he has a manual tranny with od and as you mentioned less wind drag.

Sure they are...but are they causing me to get quite literally one half of the mileage he is ?

Sure they are...but are they causing me to get quite literally one half of the mileage he is ?
Yup, very likely anyway. If there was a prob with the engine that reduced mileage, there would be other obvious symptoms to go with it.

Yup, very likely anyway. If there was a prob with the engine that reduced mileage, there would be other obvious symptoms to go with it.

Yeah, the thing runs better than ever. I guess with that industrial strength 4.10 rear end on there...it came with a really nice hitch also...I could tow a trailer weighing two or three thousand pounds without too much trouble, if nothing else.

i think it does have the j code manifold gaskets because i remember when i replaced the injection pump on it i cranked it up before i put the manifold back on and i thought it was wierd that it was blowing back out to the manifold but the gasket couldn't let it go through.

Just got back from a 500 mi trip with a stock 83 2500 4x4- 2000lbs in the bed under the topper and 60mph- I calculated 21.9 mpg, not sure of gear ratios, but it is the 700r4 OD

Just got back from a 500 mi trip with a stock 83 2500 4x4- 2000lbs in the bed under the topper and 60mph- I calculated 21.9 mpg, not sure of gear ratios, but it is the 700r4 OD
Probably 3.42's

Personally, I average 23-24, occasionally better, highway at about 60-65 with the NV3500 OD manual, 3.42 rear gears, and 31" tires in the 3/4 ton std cab long box. In the city lately I've been getting about 12-14 mpg... ):h It used to get better mileage before I changed injection pumps as well, not 100% sure as to why, but it did. For a while it was getting a consistent 25-26 mpg, which was ridiculous...

Without overdrive highway driving will kill mileage, as will low rear axle gears.That's mostly what affects mileage.

Sure they are...but are they causing me to get quite literally one half of the mileage he is ?

I wonder if you can get a mechanic to swap the ring & pinion gears on your dually axle down to 3.73 or 3.42.

Good luck getting 3.42's for that. 3.73's are, I believe, a possibility.

You can put just about any gearing you want by simply swapping axles. 3.73 is common, I have that ratio in my Suburban. You could always go to 1/2 ton axles and go to 3.08 but that would lug the engine more and wouldnt be able to tow much.

You would be absolutely disgusted with that truck and 3.08's.