mileage booster!! long trip to find out!

[T.winegar]

I'll be making a long distance trip(for me that is!!) down to Utah on saturday. looking to get the best mileage.

any tips???

tailgate open, or shut? don't know which is better...
lucas additive injector cleaner
no cb antenna

65 to 68mph

[TTipswprd]

all i can think of is to be easy on it and shift smooth getting on the highways and drive at the top of your torque curve which i think is about 65

[peobryant]

65mph is the absolute fastest I would drive if I was concerned with mileage. When you're driving something as aerodynamic as a brick, fuel mileage seems to drop dramatically over 65mph.

The most important thing is driving style. Coast up to traffic lights, take off slowly, and keep the RPM's as low as possible.

I remember watching an episode of Mythbusters, and they found that driving with the tailgate up created less drag than keeping it down. I don't know how much of a difference it actually makes though.

The Lucas seems to have different results with different people. Some say it helps, some say it doesn't. Personally, I'd just run without it.

Where is your timing? I've heard a slight increase in timing, (1/8" bump) is supposed to increase mileage a noticeable amount.

[T.winegar]

I had a friend in physics that told me to keep it up. he says going at faster speeds creates a pocket of air in your bed and once that is made the air coming over the top of the cab just runs over the truck without dragging it further down. therefore, you won't get drug down anymore. less drag= more miles

[Crossy's son]

Advance the timing and you'll wonder why the factor didn't do it...adds power and fuel mpg

[GLHS]

I had a friend in physics that told me to keep it up. he says going at faster speeds creates a pocket of air in your bed and once that is made the air coming over the top of the cab just runs over the truck without dragging it further down. therefore, you won't get drug down anymore. less drag= more miles

With 3.54s and a Getrag mine gets best mileage at 65.
How fast do you need to go to create that pocket? I did 85-90 going to Utah last year and got about 16.5 mpg.
Maybe I should step it up a bit.

[T.winegar]

I don't know to be honest. but I think it is best at speeds that suit our trucks- 55-65mph.

it makes sense, but it also makes sense to let the air flow right through... I dunno.

[93_Fummins]

As far as the tailgate thing, it has to do with surface tension and fluid friction. Air has the least resistance against itself (compared to rough surfaces, which under a microscope even the smoothest surfaces have a certain roughness), thus is the case with the gate up. The stagnated pocket of air trapped against the gate makes for a very smooth surface for the flowing air to glide along...much smoother with less firction than a tailgate that is down, especially if it has a checkerplate cover or such.

The same was said for polished ports. It used to be thought that polished ports allow the smoothest air flow, but I recently read an article that was done by a major head and intake producing company that suggested unpolished ports actually allowed better air velocity. The roughness in the ports (if done properly) actually creates little stagnation pockets of air and make a nice sliperry surface for the incoming air to flow.

I went to schoool for mechanical engineering, so I've seen a lot of tests and theories about this that prove it one way or the other, unfortunately I'm not very good at explaining it...

[dpuckett]

T.Winegar- I'd leave your timing alone- it is advanced from the factory over the IC'd trucks. I did the 1/8" thing in my 91, and stuck a gauge in there a year later, and it was at 2+ mm. Backed it down to about 1.5, and gained a couple MPGs. My own toying with timing confirms that for my trucks and driving style, 1.4-1.5 is about it.

Your 3spd auto with 3.07s gives you a final drive real close to a set of 4.10s with OD. But, depending on how efficient your torque convertor is (or isnt), you may do better going faster. My mom with her gasser-stall convertor gets better MPG at 75 than at 60. I'd try a tank at 65, another at 67, etc. I'd think 65-67 would be about it for you, both in terms of tolerable noise, and fuel mileage.

Get rid of excess weight. A jack and toolbox dont count, as they may come in very handy out west. But, will you really need all the extra stuff? I know for a highway trip, my bed gets emptied.....

Dan

[T.winegar]

ok. I'm not happy. I got as good or better mileage before I ever starting upgrading this truck. --18-19mpg

now, with all this stuff done, especially the torqconverter and pump rebuild, I was expecting more.

I went 65mph for half the trip-220miles-- and got 18mpg. 17.95 to be exact.

the last half, we hit traffic jams, and I drove it a little harder-68-70mph. I haven't checked it yet, but it went down just slightly.

So, what happened? I got that mileage before I did anything!!! maybe the 285/75s on 8in wide rims(new), the dennyTpin being in there now, or the bug guard on the front of the hood(which I had before), or the weight in the back. 3 bins(40or 50lbs a piece, a bag of clothes, desk(60lbs), cooler 30lbs.
----all this in the back, pushed somewhat to the front. the bed was full is what I'm saying. not empty, scattered stuff all over.

[Ace]

Depending on what fuel cone you got from Denny T and how your AFC is setup, you could have more fuel coming out the exhaust pipe in the form of black smoke.

[TTipswprd]

does seem low. i got 21mpg with about 450 pounds of firewood in my bed. also was 50 miles of intown driving then 100 on the interstate doing 75mph.

[T.winegar]

not a ton of smoke comes out unless I stomp it or I'm stopped and hit it pretty good. I don't know about the afc, the rebuild shop took care of that, but its the stage 2 dennyT. I believe he doesn't even sell the other anymore.

but, smoke isn't too much of it I think.

I do know that I'm pissed about the whole mess!! especially with the money I have spent...

[peobryant]

Your signature says "pump tuned to make me smile" which may play a pretty big factor in the mileage. I would back out the fuel screw to a little above stock, and go from there. Pump tuning has a lot to do with it.

[T.winegar]

well, the injection shop guy did all pump tuning. the only thing I've added is the dennyT. the 366 he installed.

so, I had him turn it up quite a bit, but nothing crazy. and it didn't smoke too terrible until the DennyTpin. I think he made it run very efficient is what I'm saying...