MPG Pt.1

[Stewart G Griffin]

294.5 miles,  16.772 gallons = 17.56 mpg    This is the best mileage since i started keeping track.

i did not install the tonneau until about 140 miles into this tank.

i like these numbers, but let's say for now results are inconclusive----should run a few more tanks to verify.

$3.59 per gallon.   $60.36 to fill.   Price has risen .15 in one week.

[Stewart G Griffin]

297.8 miles,  17.007 gallons = 17.51 mpg.   i had more stop+go driving this time.


i think i would like to confirm it;   Tonneau cover works!   i'd like to say 1.5 mpg improvement but would have to recalculate to be accurate;  i thought/think that i was averaging around 16mpg all along and with the addition of the tonneau it's 17.5 although with just two tanks this might not be accurate to call it now.

Unfortunately the aerodynamic testing and experiments are going to have to be put on hold indefinitely due to large amounts of fertilizer being spread at work.

So no more testing, but i will continue to report mpg.

Exxon regular at $3.659 per gallon.  $62.23 to fillup.

Updated specs:
78 LG3 305 engine completely stock.  This means 8.2 ish compression?
Rochester 2GC carb
Not sure where timing is because i can't find the timing tab and i'm not going to make any effort either.

Stock exhaust manifolds but with true dual exhaust but no crossover pipe.  Flowmaster 40s after dual flowmaster cats.

TH-350C trans
2.56 rear diff gear

Truck is at stock height.   Weight is probably 3800 or more.

One new pepboys "cornell"  235/75R 15
two other salvage yard$10-$20 specials Yokohama/general 235/75R 15  probably came off a toyota or mitsubishi suv/truck
One salvage yard $10 special BF goodrich 205/70R 15  Note: this smaller mismatched size is mounted on the front.

i plan on switching to new michelin harmonys or X soon.

1/2 ton longbed;   Maybe longbeds benefit more from tonneau covers than shortbeds?

[Stewart G Griffin]

Last month totals:

1) $389.59 food

2) $112. 59  gas.

Just to put it in prospective.

[snibook7537]

Those numbers are really good, I went on a trip with my girlfriends father to PA a few weeks back we were getting something less than 19 mpg the whole way, almost all thruway. His truck is a 2008 Silverado 1/2  ton 2wd 4.3 V6 No CC. we had the air on windows up and nothing in the bed. all the times we checked mpg it was around 18.6, now he drove it a little harder than I would have if I was going to try for good mpg but it was thruway miles and not too hard of the gas pedal. So realistically your truck is getting only slightly less mpg than an almost brand new truck.

[Stewart G Griffin]

250.4 miles,  16.155 gallons = 15.49 mpg

i took the toneau cover off because i was helping someone move and then i could not decide (and still cannot decide) if i want to build a shed in by parents' backyard.  i will probably put the cover on soon.

The only other change is i got a new tire.

[76k104x4]

well i only get 16 with a 2007 GMC Sierra Z71 with the 5.3 but i got a big right foot

[Stewart G Griffin]

257.9 miles,  17.506 gallons = 14.73mpg

$3.3319 per gallon regular at mobil   $58.10 total to fill up.

   i think/hope part of the problem was that i was using the very tiny mr. gasket type air cleaner---the 3 1/2" diameter and i think it got clogged.  The reason why i ran this filter since i think summer 09 was to get the carb worked out---it's easier this way but then i forgot about it----because it seemed to work well.   i have now switched back to the stock 14" filter.

The other thing was that i still left the tonneau off.   i really think aerodynamic modifications really work.

Also, there was a stretch of about 20 miles where i really had to hammer it because i was late for an appointment.  Like going 75+, which i normally keep it 65 and below.   305's run better than you might think.

[Stewart G Griffin]

275.7 miles, 17.446 gallons = 15.80mpg

$3.199 per gallon,  $55.81 total to fill up,

i'm not sure what is happening here.  Maybe it is the "winter blend" gas?

[velojym]

You could try a partial (rear mount, leave the front part of the bed open) cover, with a flap/spoiler mounted to the cab roof
angled down a few degrees. According to quite a few studies, it almost shows the drag reduction of a full aero cap, without
destroying access to the bed. I figure I'll try that on Earl in the not so distant future.

[Stewart G Griffin]

YES!   i like the partial tonneau idea---it seems counterintuitive, just like leaving the tail gate up as opposed to down, but research indicates that both are better for mpg.

i was doing some more thinking and i've realized that maybe most of my driving is not strictly highway cruising;  It is mostly on the highway (2 lanes in each direction w/ median strip, 55 speed limit), but there are quite a few traffic lights.  And when you have that, you don't have steady state cruising.  It's more like a combined city/highway mix.

[velojym]

For that, I'd be tempted to find a relatively simple, non-obtrusive "hybrid" setup, maybe a plug in electric "booster" motor tied in to the drivetrain or a wheel to take up some of the acceleration load, maybe even with some regen on braking. Also, the hydraulic hybrid that UPS is using on some of their trucks appears to  be making some really impressive numbers as well.
I know some folks aren't gonna like the idea, but I think someone with enough ingenuity and the ability to scrounge can probably have a setup that pays for itself pretty quickly.
If it's mostly highway miles, the aero mods are probably the big ticket.

I've even considered a 4bt swap in Earl, but I'm a long way from doing anything major at this point.

[wildcatjason]

I have been driving my cummins 4bta suburban for about a week now. I did the math and it will take me 70000 miles to recoup the money I have in the swap at todays fuel prices, but that includes a new tranny as well. I don't have definite numbers on the mileage yet, but I am guessing 20mpg with mixed city and highway, but I would not call it slow. I will post numbers when I have them. It is not fast by any means, but it will pass and move in and out of traffic fine. A 6.2 could be done a lot cheaper I just didn't want that engine for lots of reasons.

[wildcatjason]

I have also been reading that with a lighter vehicle like a 2 door truck that this engine will get mixed 25mpg or higher. If I could do all over again. I would in a heartbeat. Next time might be a Jeep.

[velojym]

I've heard rumors of 30+ mpg with that setup on a 1/2 ton 2wd truck, but I'd have to see it. If that were the case, however, my pickup would be right up there with my little HHR, and close to my wife's Cruze. Since I tend to want to keep vehicles a long long time, it'd eventually pay for itself. I wouldn't be averse to a 6.2 swap if I felt it would hold up for the long haul (ha! pun!), and I'm not hard on trucks at all.

Then again, if I could figure out how to beat 20 with my 350, I'd just keep it... but by the time I got to that point, I might have spent what a reasonable diesel conversion would cost. I also considered a 4.2 Atlas swap, but again... for the cost/effort, an oil burner might be more economical in the long run anyway.

[wildcatjason]

I don't have exact numbers yet, but I went about 600 miles on a 31 gallon tank with mainly city driving. I wrote down what was on the odometer and will report when I fill up again. Just let ya know I have 6000 into this swap with a new tranmission, having everything rebuilt, and a few hundred dollars worth of road blocks. I did all the labor myself. I have had this truck up to 85. Acceleration could be better, but it's pretty much all stock.