Maybe not all that better LOL.

150km on 25L of fuel

Works out to :13.8 MPG (ouch)

Lots of driving around town, but also a sprint to the next town averaging 80-85 MPH on the freeway in there as well (Couldn't find anyone local to offer the test to get a boating license!!). All empty, no babying.

Trip before that was the usual 200 mile towing run that gave 15.3 MPG (2 weeks ago)

Todays data is for another 200 mile towing run. I also increased the dynamic timing slightly before this run.
Conditions were not very good, traffic was OK, but there was a headwind kicking up for most of the way south and rain patches. For this reason I switched tanks before heading back home to show what kind of difference it can make. I was not able to measure the wind, but the for cast called for wind of up to 60 KPH (36.66 MPH)

Heading south into the headwind at 65-70 MPH(includes a few clicks of city driving before the trip so the distances will be different):

178 Kilometers on 28 liters of fuel
= 14.68 MPG

Heading north with a tailwind at 70-75 MPH
161 kilometers on 18 liters of fuel
= 20.66 MPG

Average for this trip is

17.66 MPG


The timing adjustment did wake the truck up a bit and seem to want to accelerate more easily with noise also up slightly. Smoke seems to be unaffected. Since this is the first trip with the revised timing I'll have to see what the next run is like and start a new average that way.

 

I haven't started any hypermiling yet but I took the family to the coast two weekends ago which requires going over a pretty decent pass. I didn't baby it but I didn't run real hard either, a good amount of stop-and-go driving in traffic and rarely over 60-62 mph, lot's of corners. Loaded with all 4 kids and wife and associated crap I wieghed 8300#

16.88 mpg.

Didn't think that was too bad as my normal mileage to work and back, around town etc is always 14.25-14.7.

Considering I don't have a light foot and it's a heavy truck I'm fairly happy.

 

Wind was still fighting me today, but I just pushed through it this time.

Heading south into the wind gave me 14.7 MPG and speeds slightly higher at 70-74 MPH on average.

Heading north with the wind gave me 17.4 at the same speed.

Average for the trip: 16.06 MPG

Good enough I guess. Wish the wind would die down enough to compare better to the older timing setting, but its begining to look like I might have picked up 1 MPG for my trouble.

Also had to add oil for the first time yesterday. Almost forgot how to do that heehee.

 

Ran without the trailer this time.

South: 171 KM on 21L = 19.4 MPG

North: 178 KM on 20L = 20.6 MPG

Average = 19.9 MPG

Wind was nasty today, and had the odd down pour on the way too. This has been a miserable summer. Speed was between 65 and 75 unless slowing down for stoplights. Wasn't exactly driving gently either.....

 

Did things a little different this time.

I set the cruise to 70 MPH and allowed the speed to bleed off as much as 15 MPH on some hills (enough to cause the cruise to kick out on one or two hills).

For when the speed limit dropped to 55 MPH, I dropped to about 56 MPH (usually don't slow down) and stayed in the slow lane even when stuck behind big rigs. Their slow acceleration gave me a good reason to accelerate gently. The lower cruise speed also reduced wind drag enough to let me coast neutral on a few hills without loosing speed.

As it turns out slowing down was a good call because cops were out in force today with about 3 speed traps that I drove through (many got caught).
I did a timing adjustment before this trip and am not really happy with the results, so I will be going back to the previous setting. Bogs down slightly, lost about 3 psi of peak boost and smoke is higher when pulling hard.

However this run still ended up being the highest MPG ever with towing the trailer because if the lighter driving style and slower average speed.

I got 18.25 MPG this time.

 

David85
What was your timing adjustment? Advanced or retarded

 

I tried advancing the base timing(rotating Injector pump), and retarding the timing on the advance/retard lever on the side of the pump. The intention was to increace the base timing without affecting the mid or high range timing, but it didn't work. I left the lever where it was but returned the injector pump to the previous position.

And don't ask me where exactly my timing is because I don't have a clue. I'm strictly timing by ear since I have no tool to time it by the book. I make tiny adjustments, try it and observe the results then decide which way to make the next tweak. Right now I'm thinking the timing is about as good as its going to get, since even the slightest change in either direction seems to have a negative affect.

Exhaust smoke is also quite low where the settings are right now.

 

ahhh! all through this thread,im like,when is Dave going to slow down!
glad to see you did.see,like you say,even though you tossed in 3:08's your problem is always going to be hitting the air.50-55 is probably best in your case.(thats much faster than our 3:55 or 4:10 of course as yu know,our optimisms are 40/45ish or so)your probably know better by now just what speeds are best overall.
very,very good reading.i enjoyed it.thanks!
Dave.sometime you should setup your garage here with all your mods.Id love to read about them and potential future mods you may have planed.
you,know as i read through this,i keep telling myself i swear iv read that limited slip cost a bit of mpgs.i think i read that many many moons ago,and not sure where.so if you know thats incorrect disregard as i didn't take time to search it.

anyway.VERY impressive gains you have made from start to finish.WTG!

p.s. retarding the timing in gassers increased fuel economy,where advancing gained more power-mostly take off speed.not sure how diesels are.
i did pick up a diesel book finally.man this is going to be fun.to bad about the timing tho.(says to take to shop.i need to get up to speed on here about this.)

 

Haha, I kinda figured you would find this one too. What fond memories....I guess back then I was still thinking of an all electric corolla. Currently building an electric saturn instead

I have an old fashioned gallery setup and that lists some of the mods, but it seems the garage function is a lot more intuetive. The electric car forum had one up and running for about a year now (didn't set that up either, but its a great feature). I noticed FTE tends to trail behind other forums when it comes to making updates that come out with each newer verion of the buletin forum software.

My goal was to hit an average of 20 MPG empty @ 70 MPH. So far it looks like I am able to do that, but driving empty doesn't happen very often. To be brutally honest, I'm a little less concerned about MPGs at the moment and have a tendancy to just stick my boot in it these days with reasonable fuel prices. Oh, and none of this was with the fan removed.

The 60-1 compressor on the turbo seems to have helped reading my own notes here. The boost comes on better, and speed bleed off in overdrive is much less now. If my trailer isn't loaded too heavy, I can even leave it in overdrive unless there is a significant head wind or hill.

And so far, nope. Never did make a trip at 55 MPH. Just can't bring myself to do it.

 

Anyone other than myself wire a remote starter button and a fuel pump shut off button into the dash for shutting it down at the long lights while it's in gear?

I also have issue with the 18 year old grease in the ignition not wanting to turn easily below 25 degrees so it's an easier way to start it up cold.

 

The best I ever got with my truck was 13.5, mostly empty with some towing of empty car hauler.
'88 extended cab 4x4, 5 spd, 3.55s, 265/75R16s
Front brakes are draggin a lil, once I get this thing back on the road I can start checkin mileage again- havent drove it in over a month
I can't wait to drive it again but can't afford leaf spring hangers for it right now

 

Was that highway or stop and go city driving? You should be able to reach 18-20 MPG with that setup. 3.55s and ZF5 are the best combo you can get for highway MPGs in these trucks from factory. 4x4 hurts a little, but you should be getting better than 14 MPG.

Just got home from a 200 mile trip cruising at 75 MPH for most of the way. Some city driving mixed in there too (about 15 miles).

19.4 MPG

I have to do a baseline test where I set the cruise at 70, then switch tanks to see what the average for 70 really is without other driving conditions throwing things off. Maybe some day I'll do a 55 MPH test too. Some day............

Right before they made the switch to ULSD fuel, this time of year was usually when I could touch 20 MPG even with the old C6 tranny still in it. The cool, damp air and shorter days seemed to help a lot. The truck sure seemed to like the cooler weather right now. Typically, I also loose about 2 MPG in the winter, but that seems to have been cured by removing the cooling fan last year.

Catfish mentioned earlier in the thread that fresh oil might be resulting in higher MPG numbers right after an oil change. So far I haven't noticed that, and I change my oil/filter at 6000 mile intervals. Currently around the 5000 mark.

 

It was highway, 55-62 MPH. Very rarely do I get out on the 4 lane and run 65-70. I can watch my fuel gage do down at 70 on the interstate.

One time I hauled a truck frame / body 80 miles and I had to be foot to the floor to run 60 in 5th, or 65 in 4th on the flat and 50 on every small hill. I used just shy of 3/4 tank of fuel on that run.

The whole was I was cussing this gutless piece of s**** and wishing I'd taken my 300 I6 instead. It was somewhat windy that day, but I didn't think it affected it this badly.
On the way home hauling a complete truck that was heavier I cruised at 70-75 with ease. On the small hills, foot to the floor yielded 65+ MPH, bigger ones a bit slower, never dropped below 60.

Wheras on the way up (windy with lighter truck) I could barely hold my speed on the flat, let alone any hills. Even in 4th it was gutless.

The trip home influenced me to keep the truck and fix it up. It's SO much more relaxing to tow with than the 150. It's so stable you don't have to be nervous every time you hit a bump.

 

i hope your engine is just tired or bad injectors or something chevy lol.
im coming out of the 300-6 1/2 ton's myself.
had an 84 and a 96.
i keep wondering about these old idi's and their power after reading up on them here.(tho i keep reminding myself most guys have half a million miles on theirs now and i begin to relax a bit and reflect back on my test drive lol)
hopefully with a fresh one,she will go good.
she sure tossed my ars back in the seat when i goosed her on a test run stock(and she aint no light 150 like im used to either.)perhaps with a load its another story.cant wait to find out.

 

My tanks show empty after burning through about 50 liters (capacity is closer to 70 I think).

Using that benchmark, you got about 8 MPG on that trip. Something is not right in there. Only other diesel I ever heard of getting that kind of economy was a 6.4L powerstroke.

Your lack of power is also not right.