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Discussion Starter · #1 ·
Driving my w200 from New Jersey to Arizona some time in June. My question is, what is my best chance to help my MPG pick up and help keep the rpm, and thereby engine usage, minimal. Currently I've got a 4bbl 318, NP435, NP203, 33x12.5x15 tires. I'm not positive but I'm pretty sure axle ratio is 4.11. I will be checking that out. What are some suggestions as far as helping this old 78 out on its journey cross country.
 

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Hybrid 1ton said:
Driving my w200 from New Jersey to Arizona some time in June. My question is, what is my best chance to help my MPG pick up and help keep the rpm, and thereby engine usage, minimal. Currently I've got a 4bbl 318, NP435, NP203, 33x12.5x15 tires. I'm not positive but I'm pretty sure axle ratio is 4.11. I will be checking that out. What are some suggestions as far as helping this old 78 out on its journey cross country.
Put it on a train?? ;D

Just do the typical economy things.
Make sure the tires are all at the same pressure and at the correct pressure.
Have the engine tuned and use a good synthetic oil in the engine, axles t-case and tranny.
Use the correct thermostat
Make sure the brakes aren't dragging even alittle.
Drop the tailgate if you're desprite ;D

Good driving will save the most fuel,
Keep about 5mph below the speed limit
Keep a constant speed even going up and down hills.
If you're desprite, draft a big rig. ;D

Ed
 

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Discussion Starter · #3 ·
RXT: I could see trying to position my tank behind an 18 wheeler. That'd be great, especially when I'm getting really close and my "brick wall" of a grill starts getting pelted with the aero-crest of the rigs box.

I was thinking of swapping on a two barrel but then started thinking that a well tuned, properly jetted 4 bbl will actually operate more efficiently. Tires can be pumped up completely, thats not a problem. Any suggestions about what sort of fluids to run. In engine, trans, transfer case, and rears? I mean sythetics for all, but weights? Types? I'm not exactly sure what goes in the tcase/trans. Just regular gear oil?
 

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You could use syn oil everywhere, put more air in the tires than it calls for if it's 30 psi go 40 psi, definately remove the tailgate it is worth 4 mpg, problem you have is you will have to go slow 55 max anymore and your hitting 3 grand and it will become inefficient and use lots of gas, if you have a tach keep it between 2200 and 2500
 

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well i like to draft, not the safest thing in the world but when the engine is running 3100 rpms at 75 well you do what you can. i get 5 to 7 mpg in town and like 8 to 10 on the freeway with out drafting. but that it with my 77 f-150 4x4... dam ford...
 

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Discussion Starter · #6 ·
I'm talking about a freshly rebuilt (there will be roughly 200 miles on the engine before the trip) 318, everything nice and tight. what sort of mileage should I look for out of this puppy at a nice cruising speed? Anything to increase the mileage? Mildly restrictive exhaust?
 

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put 35's on it and take the lift kit off ;D
 

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200 miles is not a good time to take a new engine out on highway cruising, it is not even broken in yet. I would not do any steady cruising for more than 20 minutes at a time until you get around 1000 miles on it. Basically, you may have to sacrifice a little fuel mileage for engine longevity. (Vary the rpm you cruise at)

In regards to fuel mileage, wire the secondaries on the carb shut. You will lose top end and uphill power, but thirsty secondaries will kill your mpg.

As was already mentioned tire pressure and tailgate will help (or a tonneau cover or topper)

Good luck on your trip :)

-SM
 

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And don't put the synthetics in the engine until it's broken in. I used to use mobile 1, but now use amsoil, It runs better with the amsoil. And like they said, keep your speed down. If I run 65-70, i'll get about 10 mpg, but if i run around 55, i get 13-14 mpgs. That's a 40% increase!
 

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Discussion Starter · #11 ·
So time (overall mph) is my trade for fuel economy? I've been doing some aerodynamic design work on the bench as well. I need to rebuild my exhaust so I've figured a terminating location (where the tailpipe will end) in relation to the crest of air that falls off the bed of the truck as I'm rolling down the street. I'm using the speed of 55MPH as my benchmark and I'll be ending the pipe right where that wave crashes, effectively creating a negative pressure zone right infront of the tailpipe, pulling exhaust gas out as I'm moving. I know its stupid, but its something stupid that seems to make sense. I'll also be integrating a crankcase pressure evacuation system that incorporates moving exhaust gas to remove the pressure in the crankcase and that'll help out. I guess I'm reaching for every last bit here because every last bit really matters when we're talking about a 6000+ mile journey. But thanks for your help guys.
 

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That doesn't really work until after 80 mph, the theory would work but at a much higher speed, since you have to remember the air underneath is being sped up
 
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Keep the truck clean, fold in your mirrors, and if you're really serious about it, build a sheet metal air dam to move the air under the truck instead of thru the suspension components. If possible, drive mostly at night, when the air is cooler and more dense. There's nothing to see in the way of scenery between NJ and NM anyway. :)
 

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Discussion Starter · #14 ·
Primer: you bring up a good point about the dam under the truck. I could probably mock something up as far as that goes and help me get throught the air a little better. Marty: The crank-evac system would work though, reducing pressure in the crankcase, at the lower speeds. The math says the other idea would work too, I'd just need to extend the tip outward the slower I go. PG: you brought up my next topic that I'll be starting in the next months. Aside from my ultimate destination of Arizona, I'd like to stop at a few places a long the way. I think its important for someone that hasn't ever seen the country to get out and do so atleast onces. I've been to more countries than I can count on both hands, but I haven't seen any more than 10 of the states, tops.
 

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Yeah but at the back you get a turbulence and it rolls back toward the vehicle, not creating the same pull as CC breather in the exhaust, like trucks the air isn't really pulling you until there above 70 mph and you have to be so close for them to make an effect, now along the side of the vehicle is better, but im not sure how it would work on a truck with the front axle creating turbulence and then again at the rear it may cause air to push out from under to the side
 

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If it exited through the lower portion of the bed on the side it may work, get some tape and tape string along the lower edge of the rocker and above (make the string about 3", 4") go and drive on a deserted road where you can see the effects on the string at speed with the mirror pointing at it, then open your door and see the effect, then lower them and raise them see how they move
 
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What kind of research have you done on the crankcase evacuation system you're talking about? I know this is a trick drag racers use to create a negative pressure in the crankcase which they claim helps to seal the rings. I don't know this for sure, but wouldn't an extended trip with negative crankcase pressure raise havoc with the oiling system?
 

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The negative psi is good, mostly for upper rpm motors and motors using weak oil rings to keep them sealed it keeps the pressure in the motor below the pistons down and the crank able to spin with out any turbulence from the air it creates when spining, keeps the oil mist down which can actually act like having a force on the crank working against it, but that only happens when we get above some big rpms, but it'll help with the oil rings
 

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What part of Arizona are you going to? 10 states and many countries, by any chance a military BRAT? I live in Tucson, and in June it is really hot! I would recommend taking a cell phone, a basic tool kit, and some extra water for yourself and your truck. Also AZ has many stretches of highway where there aren’t any services or anything for many miles at a time. If you can afford it get AAA or AAA plus. The plus will give you up to 100 miles of towing for free and it doesn’t even have to be your car, just as long as you are a passenger. For instance, last week I was headed to Yuma, AZ. I broke down in the middle of nowhere. The AAA Plus came in very handy. When I had my hood up not one person stopped to see if everything was alright. In June the road temperatures will get over 150 degrees. Make sure your cooling system is up to the task. The speed limit on AZ interstates is 75 MPH. Most people, including big rigs, drive a lot faster than that, especially in the more remote areas. Getting 3.90 gears or bigger tire will help a lot when it comes to gas mileage. If you buy one of the aftermarket cruise control units it will also help. One of the things we must realize as owners of older Dodges it that they are heavy and most likely not going to give us great gas mileage. For me and my 84 RC, anything over 10 MPG is like owning a hybrid car. Don’t get too caught up in the gas mileage thing. In the long run it’s not that much money for one 6000 mile trip. Have fun and blow you money on girls, then worry about how you will pay for gas after the fact. That’s what a lot of us did at 19 and we are all still here. You could also take a friend or pick up a hitchhiker and make them pay for half the gas. LOL
Streak-O-Lean
 
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