Better MPG: Regear vs 2WD Conversion?

[OneTime]

I have a 92 3FE 80. It currently is not my DD nor will it ever be. I currently inlist a 25 MPG, 122,000 mile, never had a problem (wish the same was true with the 80) Ford Focus as my DD. But in the future the Focus will be replaced with a company car. I plan on changing to a new department with take home vehicles. So the new Crown Vic, and wiffy's Expedition will be enough Fords in my garage. Recently I had planned to sell teh 80 and get a Montero. But this week i found out I have serious AC leak. Im to the point where I wont get back what I have but into the truck. And dont think I wont to start all over working bugs out in another rig. So I'm looking for options to keep the 80.

I would be bumping the 80 up to a Semi DD. Hopefully by then the AC will be fixed. I'll have found the short in the dash. Have had the PS gear box rebuilt and have had the BIRFs done.

I plan to retire the Focus in about 18 mos. And with gas already over 3.00 a gallon now, who knows what it will be then. I run 33x12.50 now. I would rather 33x10.5 but the 12.5 where on the truck when I got it.

So Im wondering if I would be better off regearing, or converting to 2WD? I live in Phoenix so I don't need the AWD for snow etc. The 2WD kit is about 500 and I think going to 4.88 would cost me more. I know the 4.88 will give me more power, but not sure if they will help or hurt my milage. Also I wouldn't be doing the work myself.

I was wondering what the pros and cons of the two are. I would prefer MPG and highway cruising performance over trail preformance. I plan to use the truck for Camping, MT biking trips and to begin to explore the S/W back roads.

I have a second question. My rig has 200,000 miles on it. Super clean in and out. But assumming I get all the mechanical issues worked out, does it have too many miles to start mods. I would like and small lift, some rocker and undercarrriage protection, maybe bumpers. I already have the KAYMAR rear tire carrier that bolts on to the OEM bumper. I also would like a pullbar, winch and rear locker. But wonder if 5,000 in mods is worth doing to a 200,000 mile truck. Let the IMHO's begin.

 

[Sloan]

My FJ60 has 254,000 miles on it and not only am I still improving it, it just became my daily driver. Let me also be the first to warn you that 4.88s and 33s will be like driving a turtle on the freeway. I mention this because I also have an FJ40 that is running 35s and 4.88s and it takes a lot of patience to get anywhere.

 

[OneTime]

I dont want to go slower on the freeway. I can run about 75 MPH with no trouble right now. Which I plenty for me. I would imagine freeing up the front end would provide me with more power. I really think the 2WD is the way to go for my application.

 

[Grim Reaper]

Gearing it back to stock RPM for the MPH will improve the MPG. Other factors are weight. You put heavy wheels and tires on it and MPG will go down as much from the extra weight it is havign to spinn up as the extra diameter. Best option is keep the factory aluminum and run a AT for best compromise of street and off road.

My little 4cyl 4Runner with 4.10's and 33's couldn't get out of its own way and I was getting something like 19-20mpg on the hwy. 4.88's and it keeps up with traffic just fine and on the flat in South GA I have manage to tickle 25mpg.

Speed is the killer as well. The MPG of a brick at 75 verse 65 is a bigger change then most think. If its doing DD duties you might want to keep as much gear off it as possible. Big roof racks are horrendous wind drag. Keep it slick and it will improve MPG and be a quieter ride as well.

 

[CodyLX450]

This has been attempted and discussed on IH8MUD regarding making the fulltime 4x4 80 series part time 2WD.

The results seem to be no improvement in mileage for those who have tried.

The gears however will help you, especially with driving up all the hills out here.

By help though, you'll be lucky to get 1-2mpg better...these are heavy, bad aerodynamic bricks on the road.

 

[LandCruiserPhil]

I tried the 2WD set up on a '96 80 and saw little to no increase MPG. I went back to fulltime because I hated the way it handled in 2WD. Before you spend any money pull of your drive plates and remove the front driveline and try it first.

Woohoo my 100'd post

 

[OneTime]

OK thanks guys. I'll cross 2WD conversion off my list of things to due. Which includes fix A/C, rebuild PS gear box, find short in dash and rebuild axles.

 

[shahram]

I just broke the 15 mpg personal record this week!

And you know what I've learned?

IT'S NOT WHAT YOU DRIVE, IT'S THE WAY THAT YOU DRIVE IT!!!

I've got a '96 80 with 285/75/16 AT/KOs, ARB bumper, 3" lift, and I consistently get over 13.5 miles to the gallon by keeping it at 65 mph and below. 60 mph and below garners about 15 miles to the gallon. One weekend where my wife was forced to sit behind me in a loaded Isuzu NPR freight truck, she had to do 50-55 the whole way down to San Diego and back, we got more than 16 miles to the gallon.

Want better gas mileage? Here's what you do...

--Slow the hell down! If you went an average 70 miles an hour for one hour, and your buddy did the same trip at an average 60 miles an hour, he'd arrive ten minutes after you...what's ten minutes? One dub reggae song! He got to listen to a dub reggae jam and you blew an extra gallon of gas. Plus, the truth is, you can never go much faster than the guy going slow, because there will always be some ************ doing 55 in the fast lane, and another that won't let you pass. You'll get stuck there, get stressed out, and you might gain a couple of minutes. Which makes your buddy look even smarter.

--Easy, gradual acceleration. Sure, the guy in the Infiniti is going to beat you off the line, but so what? You're going 'wheeling, and he's on his way to his manicurist!

--Ditch the roof rack (Sorry SOCALFJ). Unless you've got more than four people in the truck and a week's worth of gear, you don't need it, and it's eating your gas mileage. Keep the gear inside. And pare the gear down! Every widget is a gas vampire. As a kid, my family of four camped out of a VW Bug (with no roof rack!) comfortably for weeks at a time. You don't need to fill your Cruiser's cavernous cargo area with superfluous stuff! Leave it at home, you won't miss it!

--Keep up the vehicle: regular oil changes, clean air filters, properly inflated tires.

Trust me. Advice given at three in the morning is always good advice.

 

[powderpig]

About the only way to increase the fuel ecomony on the 3fe 80 is to rework the engine. If you do your own work and are confindent that you can work on engines, remove the head, decarbon the engine. Have the head work done, mill off.030 to .040 and put it all back together. This will wake up this engine. You could also port and polish the(in/ex) ports and clean up the combustion chambers. Have the injectors cleaned, maybe even put a bored over throttle body in it. Performance will come up, you will not have to run preminum fuel.
I would do a compression check first and if the numbers are good, this in my opinion will be the best bang for the buck. narrow tires are better on this beast, over fat ones as well. Good luck with the choice

 

[upcruiser]

Shahram is spot on there. I get big gains by just being really patient and going 55-60mph.

I've been carefull with upgrades to my truck in an effort to keep weight down. My biggest issue though has been my reliance on my roofrack and I'm currently debating going with a rear bumper now to stow stuff despite the extra weight. Roof loads on a 3FE 80 make a huge difference in mpg and top speed on the freeway for that matter. My other plans are to switch it up to 33x10.50 AT's on my factory aluminum rims. I'm hoping to get consistent 15's after that.

 

[shahram]

Shahram is spot on there. I get big gains by just being really patient and going 55-60mph.

I've been carefull with upgrades to my truck in an effort to keep weight down. My biggest issue though has been my reliance on my roofrack and I'm currently debating going with a rear bumper now to stow stuff despite the extra weight. Roof loads on a 3FE 80 make a huge difference in mpg and top speed on the freeway for that matter. My other plans are to switch it up to 33x10.50 AT's on my factory aluminum rims. I'm hoping to get consistent 15's after that.

I am a firm believer that weight is much less a factor than drag. When I was a teenager, I used to race bicycles. Track bikes, to be exact (velodrome). What I learned was that it took nearly double the power to go from 40 mph to 45 mph in an all-out sprint. And not because of the weight, but because of drag. Aerodynamic drag increases exponentially with speed.

I garnered this little gem from Wikipedia:

"The drag coefficient is a common metric in automotive design, where designers strive to achieve a low coefficient. Minimizing drag is done to improve fuel efficiency at highway speeds, where aerodynamic effects represent a substantial fraction of the energy needed to keep the car moving. Indeed, aerodynamic drag increases with the square of speed. Aerodynamics are also of increasing concern to truck designers, where a lower drag coefficient translates directly into lower fuel costs.
About 60% of the power required to cruise at highway speeds is taken up overcoming air drag, and this increases very quickly at high speed. Therefore, a vehicle with substantially better aerodynamics will be much more fuel efficient. Additionally, because drag does increase with the square of speed, a somewhat lower speed can significantly improve fuel economy. This was the major reason for the United States adopting a nationwide 55 mile per hour speed limit during the early 1973 oil crisis as slower traffic would save scarce petroleum."

 

[upcruiser]

My concern with weight was more of an concern for maintaining the ability to keep some sort of acceleration with the 3FE. That said though, for driving where you are decelerating or accelerating more the extra weight becomes an economy burden as you are fighting inertia more. Once up to speed on the highway I agree that drag is the biggest issue no doubt. The exponential increase of drag is really noticeable if you look at all the exotic sports cars out there that can top 180mph then compare there bhp to the small few that can top 200mph. That last 20mph typically requres some sever air management and a very health dose of power.

 

[preacherman]

I got 2 mpg better when I took off my roof rack. Kinda surprised me. I did not think it would be that much.