94 4.0 possible re gear for mileage.

[Rose2300]

I would just leave the gears as they are. Lugging the engine is just as bad as high revs over time. 2700-3000 rpms isn't even that high. and with the auto trans, trying to stay in overdrive at 2000 rpms would be near impossible anyways, as it will downshift if you try to pass or are on a hill. I agree with Gotta_GoFast. Your after market cam more than likely altered the torque curve.

 

[offduty]

The engine is capable at operating over 2000rpm for extended periods of time. However, there is a lot more resistance at 70mph and the numerically lower gears require the engine to produce more torque than it would if it sat at said rpm at 55mph.

Chances are with an aftermarket camshaft you have essentially shifted your torque curve farther up the rpm range. This might be hurting your fuel mileage and swapping to a lower gear might make it worse (and feel slower). The extra wind resistance from the shell plays a huge roll at 75mph, too.

Oh, and 99 rangers were OHV, 2001 is the first model year of the SOHC.

If you drive this far and need better fuel economy look for a small car.

There is a stock cam in this truck and I am not looking for a little car. I am aware of the laws of kinetic energy and the array of lighter, more aero dynamic and efficient vehicles we have to chose from. Please dont anyone take this the wrong way but I am a man, I drive a truck, and hate the Prius

 

[Rose2300]

with an autotransmission, regearing to lower gears will essentially render your overdrive useless. More wind resistance at 75 compared to 55= the trans will be downshifting into fourth to maintain your speed. You may be running 65 @ 2000 rpms, but 2k in an overdrive gear at 65 mph is not enough to effectively maintain speed.

When I switched from 24 in tires to 30 in tires, my gear ratio was reduced from 3.45 to around a 2.84, and when I shift into overdrive at 75 mph, I start losing speed. I know I have the less powerful 2.3l, but the concept still applies with your 4.0

 

[offduty]

with an autotransmission, regearing to lower gears will essentially render your overdrive useless. More wind resistance at 75 compared to 55= the trans will be downshifting into fourth to maintain your speed. You may be running 65 @ 2000 rpms, but 2k in an overdrive gear at 65 mph is not enough to effectively maintain speed.

When I switched from 24 in tires to 30 in tires, my gear ratio was reduced from 3.45 to around a 2.84, and when I shift into overdrive at 75 mph, I start losing speed. I know I have the less powerful 2.3l, but the concept still applies with your 4.0

Yeah I hear ya, The same thing happens in my Bronco if I try to take much of a hill in OD as I put an E4OD in it and with the boat in tow it is best to stay out of OD unless going flat or downhill.

 

[Rose2300]

Yeah so depending what gears you have you could switch them out. personally I wouldn't go lower than the 3.45's as the 3.27s and 3.08s are useless in a pickup. You could get a beater 2.3 ranger for commuting lol

 

[jcd302]

I drove 70mph. I did not have a problem with the OD shifting in and out, even with the 3.08 gears. I pulled large trailers with this thing, even hauled a '67 Oldsmobile up from Indiana with it. Constantly pulled trailers over 2000#. I sold it just shy of 200,000 miles and see it still driving around town occasionally. Looked last time (early summer) and he has 235k on it now.

Alot of comments here are speculations or 'logic' (what should happen). I am telling you from real world experience what I experienced. Mine came from FORD equipped this way. The only thing I did was changed to a traction loc spool from a late 80's Mustang. Open diff sucks in snow!

 

[LameDuck]

Install a vacuum gauge to see how much you are lugging the engine while driving. I've done this to my truck and it made a world of difference. If I can keep the vac at 10-12 inch when doing 65 I can pull a solid 25 mpg with my 2.9. That's with a 3.09 ratio and 225/70-14's.


Sent from Satan, using Tapatalk

 

[Hahnsb2]

OP, tell us what gears you have now and your tire size.

MPG wise, a 4.0 will be happiest around 2400@70mph.

 

[84bluebronco2]

When I got my first 4.0 (94 explorer), I tried to keep the rpm in the 1500-2000 range with an m5od and 3.27:1 gearing and the factory 235-75/15 tires. I usually got around 15 or 16 mpg and found it hard to maintain OD on any incline and sure as hell wasn't passing anything.... When I started trying to keep the rpm in the 2000-2500 range I peaked at 22mpg doing 55-60mph. My Explorer doesn't accelerate incredibly well with 3.27:1 gearing, and I can pull around 18-19 out of it at 70mph.

My 4.0 loves 2200-2400 rpm all day and gets better mileage than it did trying to keep it around 2000 rpm. 3.27:1's serve one purpose, and only one purpose: good highway running gears. Before the question gets asked, the truck received fresh wires, coil pack, motorcraft plugs, air filter, fuel filter, and an intake cleaning about 5000 miles ago.

Hope some actual experience helps you out some bud!

 

[offduty]

I do appreciate it guys I will find out tire size and gears when I get home. I wont be home till monday afternoon.

 

[bobbywalter]

i understand your intention.


your premise is off a bit though.....55 wasnt the speed limit in 94. but your premise is right, more right then many care to apply.



your best bet is to dyno the vehicle and find the torque curve...gear it to that with 75 mph the cruise base.

the balance of it all is tough to nail down. i myself play this game all the time..

it cost me 80 bux to drive my 8000 pound(7200 # unloaded) psd van 1600 miles...it averaged 20.8 mpg. on straight diesel it gets 22-23 mpg @ 62-65 mph...thats one way to work site...

my ranger is on its last legs, its equipped with a 6.5 diesel. it needs injectors and a pump as they are just worn out...still pulls 17 mpg.

when it was sub 300k 20 plus mpg was easy under 60 mph....410 gears 33-35 in tires.

but i couldnt drive it comfortably above 65 mph....mpg went 20 plus to 16 hiway above 60 sometimes lower.


put on 37 in tires and i can comfortably cruise 75 mph.....yaaaay. but uhhhh...mpg loss. no 20 mpg.

likely a turbo and fresh fuel system tuneup will put it over 20 mpg at 68-72 mph.

planning on finding out here shortly.

operating an engine out of its power band is a sure way to 14 mpg if its mechanically sound.....


if you have buddies close that can let you test larger and smaller tires, it will be the easiest cheapest way to nail down your suspicions with reality.


i have bought tires on wheels from the junkyard and done that to dial in my e350

355 gears and skinny 32 in tires with the e4od gets it done pretty good.

20.8 mpg on a 30/70 mix of fuel and used oil with 8 k of vehicle/load just perplexes me.

my ranger new never did that

14-15 mpg with a 2wd stock power mini truck would land me into a swap situation....either swap to a better vehicle or better powertrain.

start with smaller tires and make damn sure your way to track miles is accurate....maybe you are really getting 18 mpg and your speedo is just off.


you have me interested in what you can tune to.

 

[racsan]

my truck is a '93 with the 4.0 ohv, its running a 5 speed manual and 3.73 gears, stock 235/15 tires, best milage ever was 19.5. im turning 2,000 in o/d @ 55, 2,500 in 4rth gear @ 55. the one thing your forgetting is that wind resistance is playing a part here, and the faster you go, the more its going to affect the mpg's, gearing it so the engine isnt spinning as fast will only make it work harder and use more fuel. its a truck with all the areodynamics of a brick, sure a 2.3 will do better on fuel with the same chassis, i had a '88 that was setup the same except for it was a 2wd and my '93 is a 4x, but even though the 2.3 truck would get 28 highway, it had alot less tourque, id rather have the power when i need it instead of having to downshift to 3rd and hold it to the floor just to maintain speed on a long upgrade (and i was running empty on that road at the time) my 4.0 i can leave it in o/d , set the cruise and it powers happily along. with higher gears its just going to be lugging the engine and you will actually lose milage.

 

[bobbywalter]

my truck is a '93 with the 4.0 ohv, its running a 5 speed manual and 3.73 gears, stock 235/15 tires, best milage ever was 19.5. im turning 2,000 in o/d @ 55, 2,500 in 4rth gear @ 55. the one thing your forgetting is that wind resistance is playing a part here, and the faster you go, the more its going to affect the mpg's, gearing it so the engine isnt spinning as fast will only make it work harder and use more fuel. its a truck with all the areodynamics of a brick, sure a 2.3 will do better on fuel with the same chassis, i had a '88 that was setup the same except for it was a 2wd and my '93 is a 4x, but even though the 2.3 truck would get 28 highway, it had alot less tourque, id rather have the power when i need it instead of having to downshift to 3rd and hold it to the floor just to maintain speed on a long upgrade (and i was running empty on that road at the time) my 4.0 i can leave it in o/d , set the cruise and it powers happily along. with higher gears its just going to be lugging the engine and you will actually lose milage.

think about this.

 

[Hahnsb2]

When I got my first 4.0 (94 explorer), I tried to keep the rpm in the 1500-2000 range with an m5od and 3.27:1 gearing and the factory 235-75/15 tires. I usually got around 15 or 16 mpg and found it hard to maintain OD on any incline and sure as hell wasn't passing anything.... When I started trying to keep the rpm in the 2000-2500 range I peaked at 22mpg doing 55-60mph. My Explorer doesn't accelerate incredibly well with 3.27:1 gearing, and I can pull around 18-19 out of it at 70mph.

Same experience I had with my Explorer.

 

[offduty]

think about this.

Well eventually I will drop in a 4bt and ZF5 but I am not ready to do that yet.