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7.9 MPG. Need to get better MPG! What can I do? ATT?

WarWagon

WarWagon

Well it hits on 7 of 8...
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This is pulling a 24' cargo trailer loaded to the Payson area. I have one gear left on some of the pulls. (running in 2nd @ 35 MPH in a 65 zone.) Even my Trailblazer SS would run hot pulling the 19' jet boat on this run.

My round trip MPG was 7.9 MPG. This is short of my 8 MPG estimate for the trip. (She gets 14 MPG short trips city/freeway mixed driving no trailer.)

I want to improve the MPG and if possible the power.

Notes:

I can feel the torque converter lock up in 3rd gear at times, manually shifted to 3rd, and it accelerates better when it is locked. Aka it does accelerate locked vs unlocked at ~80% throttle.

I have removed the snorkel, new crossover, 4" exhaust with 3" down pipe, 1/2 turn on IP screw, driver instructed to back off from any smoke, new injectors stock type, HO water pump, new radiator and cleaned other radiators/condenser. Stock down to the GM3 turbo otherwise.

Pyrometer and boost gauge to be installed ASAP. Kennedy 20" fan and clutch on the way.

Suggestions?
So far I am looking at a turbomaster.
Or skip that and drop on a ATT?

A TCC lockup override switch.

Other ideas?

Again #1 goal is better MPG and 2nd goal is 36 MPH :D
 
Crankme69 said:
What temperature T stat are you running?
Click to expand...

Good call.

Will be running a 180 as soon as it arrives to keep it in line with the low temp clutch - it will get plenty hot here regardless. Discovered temp sensor has failed so not sure what it has in it now. Possible current t-stat is stuck open.
 
I would think depending on your funds. At the very least a turbomaster next step would be a gm8 then the next would be a att. Tcc lockup would be a good cheap help too. Also for where you live I would seriously consider WMI.
 
what axle gear u set up with? 373? I went from 411 to 373, before 14 empty 12 tow, now 16 empty 10 tow. maybe spending $330 to go back to 411 this summer. have u cleaned intake, FTB mod, good LP? what mileage on injectors and pump? injectors can rob power and burn piston.

I do not believe any cheap way to get more power and better mileage, especially under load. with our engine, I simply look for a way to run cooler with consistent power. I would look at Heaths new water pump setup.

anyone running 411's that tow, stay with it.
 
4.11 rear end. Something set up right for a change on this!

Was the ATT MPG % towing?
 
att will give a small percent improvement, major advantage in better flow, less back pressure. I really doubt its gonna give you substantial increase-definitely a good investment.

what is status on injectors and pump.
 
As in 1st post injectors are new and pump, Original I guess, now has a 1/2 turn on the screw.
 
Turn fuel screw back to stock and use cruise control when you can.

My old 93 2wd, 373's (When limit was 55mph) would get 26 mpg empty, on cruise w/tailgate down.
It was stock except for K&N and muffler was cut off. That was back in 93 before the aftermarket supported these trucks.
 
Before available fuel switched to winter blends, I saw a pretty consistent 1 mpg increase simply from switching 180 -> 195 thermostat. Does John K. recommend 180 degree 'stats with his fan clutch? Assume the idea is fanwash air thru the radiator (195 stat) may keep the fan clutch engaged more/too much of the time?

In the absence of aftermarket coolant temp gauge, it's tough to know if it's really running 195 + some of the time. Although I would agree, it's probably comfortably there & above while pulling hard. With the additional surface area of the coolant surrounded IDI/pre-cups, I believe these trucks probably see fuel economy impacted by coolant temp a bit more than DI engines.

The 4.10's (RPO - GT5) obviously help w/ towing & hurt mileage otherwise. General reports on the 4.10 equiped trucks seem to be around 2 mpg lower average.

It's likely the higher average rpm (particularly while loaded heavily) would show more fuel economy benefits from a lower restriction turbine like the ATT's. Higher ave rpm ~ higher ave hp ~ higher ave mass airflow ~ higher % of the time in it's most efficient range of operation.

In your location, do fuel stations change fuel blends much/at all in the coolest winter months?
 
If you have a cooling problem thats something to troubleshoot. Running 35 actually should make your cooling worse than at 55mph, seeing as you need the fan engaged to get good enough flow through radiator. At higher speed you will get more air flow. That truck should be able to pull 10K lb without a problem, unless there is a problem with it.

The free fan clutch mod is better than the clutch upgrades from vendors. The new types of fans are likely better though.

And running 35mph is less efficient than 55mph as well.

Make sure your LP is working during operation and under load while driving.

An ATT will help a lot if Power, IATs and EGTs are your problem under load. If you have a cooling system problem should fix that first.
 
Wow. I'll be honest with you I don't know how on earth you manage to get 7.9 MPG. bone stock and driving like a jackass left me nothing less than 13mpg. I've never seen less than that, even with a fully loaded landscape trailer weighing several tons. Yes thats with 4.10 gears.

I vote ATT. That combined with a free-flowing exhaust has given me 18 mpg during the summer months doing 65mpg turning 2300rpm.
 
Have you checked the timing?

Pushing that much wind and todays crappy diesel, with an auto/unlocked converter 7.9 might be about all you can get.

When the 92 with a 5sp was new with the good fuel, I'd get 10-11mpg towing my 24' stock trailer, when I quit long distance towing around 200k on the LSD I'd get 9-10mpg, I dont know what it would get on ULSD. When the 92 was new it would get 24mpg empty, I put 700 miles on alot of tanks of fuel.

The D-max gets about 10.25-10.5mpg pulling the same trailer now, but pull a 32' mostly now @10-10.25mpg. I think the D-max main towing advantage on mpg is the intercooler.
 
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