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Fuel Economy Solutions

A

adamhammer

New Member
Messages
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Location
Traverse City, MI
Hi,

I'm currently running around 10-12 mpg around town. I was wondering if there's anything I can do to improve this. The engine is stock. I'm looking to do some long haul towing and wouldn't mind if the towing mpg were around this, but with no load I should have just bought a gasser.

I've thought about a Heath chip and turbo master. Im shooting for lower$, bolt on mods until the bankroll gets bigger. Any tips you guys can give would be great.

'95 K2500, stock 6.5L, 230,000 mi, new IP, new injectors


Thanks,

Adam
 
Turbo masters can give you more power and will keep the economy the same towing or make it worse with light load. A tune can do the same as the Turbo Master with the factory vac system w/o as much MPG loss.

Exhaust needs to be 4". Including 4" kitty if you have to keep it.

Your gas MPG around town would be single digits and towing really bad. 6MPG gas vs. 7MPG 6.5 towing hard. Foot to the floor over 80% of the time.

You want to get a bigger turbo for towing. The more load the more MPG the bigger turbo gets you. The factory turbo simply chokes the engine turning MPG into heat that kicks the fan in. The A Team Turbo gets me 15 MPG on the burb in town, but 10-12 isn't uncommon with all the diesels I have depending on the town and amount of sitting/stop-go at lights. The turbo change has improved my MPG the most and one of the only things that improved MPG towing. The above MPG went to 10.4 for me towing the foot to the floor route with a 28' cargo trailer and MPH went from 43 to 55 on the 7% grades.

How old is the timing chain? Tstat getting it up to temp? Coolant sensor working? How much blow-by? - indicating ring condition for the high miles.
 
I have no clue on the condition of the engine internals, it's a new t-stat 195*, the temp gauge reads around 195-200 all the time. i've never seen it go above that, however northern michigan hasn't seen real high temps. As far as doing a leak-down test for blowby. I have a leak-down tester, just no adapter to do it. Would this be something I could do through the glow plug port (just need an adapter)? I'd rather not go through pulling the upper intake and turbo off to get at the injectors. I just went through that 3 months ago with the IP and injectors. Again, I'd need some sort of adapter for the injectors anyway.

I guess since I haven't had the chance to really take it on the highway, I don't know what that MPG is. I just know that I've heard several people with their mpg in the high teens if not 20's and maybe they're blowin smoke up their own a**, but I cant imagine this doing much better with out some work or $ to improve the combustion efficiency.
 
At the very least upgrade the exhaust to a 4in system. Bigger turbo will also help greatly. I do believe you have to go through the injector openings to test for leak down and compression. You should be able to remove the injector and screw in the tester with the lines on just push it gently out of the way, I had no problem doing this while a changed an injector.

Good luck
 
Brooklyn Tow said:
Your Foot determines the MPG significantly.
Click to expand...

2x

Synthetic oil has boosted mine.

Replacing my boost control solenoid also up'd my mileage too. It was leaking and not giving me full boost. A T/M would have fixed this too, but fixing the solenoid did not require a tune change.


I typically had been 11 to 12 in urban driving. 14's on the interstate below 65mph. 12 to 13 below 75.

After the oil change, MPG increased.

12 to 14 in town and hit 16 on my last highway trip. (kept it below 63)

This is all on a stock setup and 4.10 gears w/ 265/75R16.

Depending on your gears, dropping your speed helps a lot. Need to keep the rpm's in the power band, 1800 / 2100. If you run in the 2200 / 2300 range mileage drops off pretty quick.


Now 4" exhaust, 3.73 gears and losing the aluminum topper and the junk stored in it, would boost my mileage.
 
Brooklyn Tow said:
Your Foot determines the MPG significantly.
Click to expand...

:skep: This has never changed my MPG. I can stand on the throttle or press it lightly. Same MPG. :skep:

Because when it is on the floor it doesn't matter if you stand on it or hold it lightly: It is still floored! :rof:

Floored all the time MPG and MPH (AKA towing hill/mountain climbing) is improved by better breathing. Exhaust and turbo.

The RPM's given above are peak torque and the last gasp of the GM turbo before the wastegate just dumps exhaust becoming restrictive in higher RPM's.

Timing from a worn timing chain can affect MPG.

Going NA will help MPG.

Freeway I get 14-15 MPG at 75ish with the stock turbo. Slower and your MPG goes up. Some get better MPG on the freeway at slower speeds. Rear end gearing and tire size also makes a difference to the speed you run at 2100 RPM.
 
I'm actually testing Kojo multi tunes chip on my Blazer. I'm at the moment set on the "economy tune"

I'm with a GM-5 + turbo master, stock exhaust with stock muffler (AT3030XL and other goodies not arrived yet)

I'm driving mostly around town, with no A/C (dead evaporator :18: ).

This is my first tank, as I get the BLAZER insured only this monday, but it seems to be very promising. At first glance, it seems I'm around 17~18 mpg, which is not bad if we consider traffic conditions, and the GM-5 + turbo master which is not built for economy...
 
I think it boils down to intake and exhaust restriction. my 99 chassis cab with the GM8 (the best GM turbo, still not as good as an ATT, but better than a GM3) has hit 18.5 mpgs, averages 14, and gets down around 11 towing hard. my 96, hit a record of 23, but averaged 18-20 empty. loaded (lightly towing a car trailer) 14-15.

now compare that to my new 93 K2500, stock right down to the dumb ol GM3. at 70-80 mph, I calculated out 8.7mpgs. EMPTY NO TRAILER!!! that was over about 700 miles and 3 tanks. then I started hauling with it, but this time I kept it around 58-60 mph, roughly around 1900-2000 RPM. now wouldnt you know it, even when loaded to 18K combination for 150 miles, 12K combo for another 50, and back up to 15-16K combo for the return trip of 200 miles, I averaged about 12 mpgs.(similar load for two trips, so total of 800 miles) it seems like that restrictive GM3 turbo murdered my high RPM mileage.

compare that once again to my 91 C1500, granted it is a light half ton, but if it can clear 20 mpgs at sustained 2600-2800 RPM, it must say something about the lack of the restrictive factory turbos.

another variable is that I keep the OEM wastegate controls on, so my 93 is still the OEM springcan, and the 94+ rigs all have the OEM vaccum control.

and, i definitely credit awesome MPGs to 2wd and manual transmissions! but unless you bought one that is equipped that way, you are stuck with what you have.

how heavy of pulling is planned?
 
adamhammer said:
As far as doing a leak-down test for blowby. . . . Would this be something I could do through the glow plug port (just need an adapter)?
Click to expand...

I found two crude measures of blow-by, one is by warming the engine, removing the oil filler cap, and looking for vapor coming out of the tube. The second is the bucket-test by using 3/8” ID clear tubing with one end on the dip-stick tube and the other in a bucket of water, IIRC the indications are:
> Normal:
+ Idle = 1/4" to 1/2" pull into tube
+ 2000 RPM = 1/2" to 1" pull into tube

> Fail (blowby):
+ Neutral (no vacuum or pressure)
+ positive pressure and / or bubbles in water

The bucket test might give a false positive if the CDR is not working correctly.

For mileage, with 3.73’s and stock sized tires I’m getting 18 – 19 with light to moderate throttle and around-town / highway driving mix (known mods in sig), but am finding that an Italian tune-up every other tank tends to keep the mileage in the low 19’s (do not know the history of the engine prior to 10K miles ago, so suspect I might have injectors and / or an IP overhaul as maintenance items in the near future) and it slips to the 17 – 18 range if I do not do it.
 
but am finding that an Italian tune-up every other tank tends to keep the mileage in the low 19’s



Italian tune up??
 
I've heard of guys decarboning an engine by getting it good and warm and running a garden hose down the intake. as much water as it will take without stalling it along with a lil throttle
 
To the OP, can you fill out your signature, and explain any recent maintenance such as inejctors and IP, who did them and was there a change with them?

What gears do you have? What is tire size? And what are your around town speeds.

I would check for dragging drum brakes. Around town the turbo shouldnt matter a whole lot, but will on the highway and especially towing. The exhaust is a biggy, if it has a kitty on it, you can be assured its probably not doing good after 230,000 miles. You might be leaking fuel too. Make sure the fuel heater is working. Warmer fuel is better atomized and more easily combusted.

And for clarification you were describing a crompression leak down test, or in other terms blow by. A glow plug adapter is the best option for that, just get a threaded rod to spin in and put whatever adapter on the other end to connect to pressure gauge. You should have about 400psi, so most gasser gauges wont work. Make sure the batteries are good for that test, cranking RPM makes a big difference. Maybe even have a low amp (10 amp or less) charger assisting them while cranking.
 
ak diesel driver said:
I've heard of guys decarboning an engine by getting it good and warm and running a garden hose down the intake. as much water as it will take without stalling it along with a lil throttle
Click to expand...

Careful here as you can hydro-lock the engine bend rods and such. I do this with a spray bottle into the intake every so often on my high performance high compression Vtwin Harley very light amounts and it still scares the b-jesus out of me.
 
matuva said:
what the hell do you do with spaghetti to keep mileage in the low range??? :D
Click to expand...

Man Oh Man . . . am certainly into care and feeding of the engine, but prefer to stick with hydrocarbons and rather than carbohydrates :thumbsup:

Short version: Italian tune-up = right foot + skinny pedal @ firewall (as great white mentioned)

Google results: http://en.wikipedia.org/wiki/Italian_tuneup

Point is not to punish the engine, but run it WOT for a reasonable duration and heat up / blow stuff out. Generally, it best done under load (towing or going uphill) to extend the amount of time at WOT and the upper RPM ranges, so in my case I get a ~15 second run up a nearby 4% hill in 3rd. This likely will not apply for engines with WMI as the water will do it on a regular basis.

Oh, and to the comment about using the Italian tune-up for keeping my mileage at the ‘lower’ end of the mpg range, 19 mpg is my *higher* end range per the original post (not l/K where higher is worse). With 3.73’s, 4WD, TCC unlocked ~50% of the time, and unknown type of fluids (viscosity, etc) still in the drive train, 19 mpg appears reasonable for me, but naturally I want better which is why I am here :hihi:
 
great white said:
Hammer the piss out of it for a bit.

The phrase you'll often hear is "it blows out the carbon"....
Click to expand...

To further clarify, it's generally not recommended.

It's a bit of an "urban myth", unless your vehicle does nothing but short hops (ie: start stop with insufficient warm up time) all over town.

A good 30 minute run down the highway at legal speeds does a better job than "foot to the floor" any day....

ak diesel driver said:
I've heard of guys decarboning an engine by getting it good and warm and running a garden hose down the intake. as much water as it will take without stalling it along with a lil throttle
Click to expand...

Whoa!

Definitely not recommended!


If ya wanna "steam clean" the insides of the engine, go get a properly designed Water injection kit and turn it on every now and then....you get the benefit of lower egt's as well.

But hey, it's your dime and your time if ya wanna stick a garden hose in the intake.......:nonod:
 
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