Going in circles! Stock, gears or 4.0?

[4.0B2]

I spent way to much money on my 2.9

Cam, throttle body, spacer, intake, polished stuff, so on... And I was never happy with it. The 4.0 is a No questions asked mod if you've ever done it once. If I ever get another 2.9 rig, the 4.0 swap is my FIRST mod.

 

[4x4junkie]

I'm only imagining 4 scenarios for you guys getting such poor mileage with your 2.9s...

1.
You are lugging it at too low RPM (saddling the poor thing with bigger tires & stock axle gears and/or you're shifting too soon),
2.
You have an A4LD behind it,
3.
The engine is simply well past it's prime (or is not tuned properly),
4.
Any combination of the above.

2.9s need lots of RPM (more than some people realize). If it can't spin fast enough, then the result is a total lack of power and guzzling of fuel (an automatic trans only magnifies the situation by huge proportions)
My BII's 2.9L was frequently getting 22, sometimes even 23 MPG on the highway (buzzing along at 2600 RPM @ 60 MPH w/35 PSI in the tires). The 4.0L in my Ranger OTOH I usually get about 21. Sure, that's not exactly a huge difference, but it is a difference. I have to agree with the OP, if the engine is still in good shape, I'm not sure I'd pull it either at least until it's time was done. At that time, then by all means, do the 4.0L swap.

On that note,
4.10 gears would certainly be an improvement over 3.73s (should help MPG, not hurt it), though I couldn't say by how much (3.73-4.10 isn't exactly a huge jump). 4.56 gears would be a much more noticeable difference, and would allow you to bump up to 31" tires too if you wanted. Another option might be keep your 3.73s and drop down to the stock tire size (205/75R15). My BII was actually pretty fun to drive on the street with those tires before I lifted it (had 3.73 gears too).

 

[country0001]

Check the classifieds on here, I think there are a couple 4.0's with harness for sale. Its worth every eadache it'll give you during the swap. I get 21 mpg hwy out of mine. I've seen 33's on one with a 4.0 still get 16.

Bottom line, do the 4.0.

 

[pontiacfieroguy]

I ususlly managed 28hwy out of my88ranger
2.9 5spd 2wd and around 22cty shifting between 2k and 2.5k and with 93explorer 4.0 automatic 4wd never got more than 15 hwy and 12 city and I usually drive my trucks pretty easy so I think if mpg is the goal then 2.9 is the way to go

 

[superdave1984]

I have had seven or eight RBV since 1988, without exception the larger engine has gotten better mileage.

The 2.9 got better than the 2.3, the 4.0 got better than the 2.9.

Right now I have an 88 longbed Ranger with 2.9 5sp 4x4 and 4.10 gears with 235/75-R15 tires. A hotrod it is not. I see either a 4.0 or a 302 in this trucks future.

Robert

I have a good donor for you.

 

[MJ'sBlkBII]

I appreciate the insights. Ok, after a few more days of deliberation I have figured out what I am hoping to achive with this up to the end game.
I don't plan to put a lot of effort into the motor knowing the 4.0 would be easier and cheaper than all the upgrades I can do, and should still get better results for all the work. I'm not jerk enough to think I can turn it into a screaming power house. I have my Hemi for that, and it's more stable too! I'm just aiming for basic improvements that the factory couldn't do for what ever regulations they were battling at the time, UNTIL the 2.9 gives up the ghost. I just have to get used to the lack or misplacement of power.
My compression is good. I have 1 weak cylinder but it is within 15% of the others. I have the stats posted on another post around here. My first BII was like what ADSM08 said- hit the hill at 70, drop 2 gears and barely made the hill at 55. This one I hit the hill at 75, drop 1 gear, and still make the top at 75. I have already swapped the larger throttle body from an '86, and have run a new Cat-back system. I have to replace the exhaust system Cat-forward next. All my power is at 3K rpm+. The cam idea was only to get the power band moved down to at least 2K rpm. As a side question, wouldn't changing the axle gearing essentially (by slimest of definitions) do this? I am pretty sure I can do the gear change cheaper than the motor swap and have much less down time for it. I can do one axle at a time, per home time.
Thanks again for the ideas and info thus far!

 

[Brownie Mobile]

Gears first to appease you for now, then do your swap later when you have the proper amount of cash flow, also why not a 302? Maybe its just cause im a v8 guy but id take a v8 anyday over any other motor.

 

[MJ'sBlkBII]

V8 is not an option for several reasons actually.
First off, because I already have one with the Hemi. The idea for the BII is a run around town that is easier on the gas.
Second, I am a very spirited driver and it is just stable enough for how I drive it. Adding the body lift to clearance for the V8 will reduce that significantly.
Third is the work to shoehorn the motor in, then still having to work on it afterwards. I prefer the easy access of the V6's in the tiny engine bay. After my wifes '99 T/A, it will be a long time before I get in another such situation. LOL
Last, I want to keep the manual tranny, and with the admittedly little research I have done on it seems as though the automatics are the only option. Please don't berate me for the last point. It may not be acurate, but with the other points listed I haven't bothered to find the answers to be sure. It wasn't worth the time to reseach it fully.

 

[hoosier1104]

I do not have a B2 but I do have a 302 w/ auto trans and 4.10's, I get about the same mileage out of my 302 as I did the 3.0. If not better. I did mine bc I needed more power.

 

[Brownie Mobile]

V8 is not an option for several reasons actually.
First off, because I already have one with the Hemi. The idea for the BII is a run around town that is easier on the gas.
Second, I am a very spirited driver and it is just stable enough for how I drive it. Adding the body lift to clearance for the V8 will reduce that significantly.
Third is the work to shoehorn the motor in, then still having to work on it afterwards. I prefer the easy access of the V6's in the tiny engine bay. After my wifes '99 T/A, it will be a long time before I get in another such situation. LOL
Last, I want to keep the manual tranny, and with the admittedly little research I have done on it seems as though the automatics are the only option. Please don't berate me for the last point. It may not be acurate, but with the other points listed I haven't bothered to find the answers to be sure. It wasn't worth the time to reseach it fully.

yeah im not too sure about that either but v8 stangs came with a manual option i think? So that pairing would work as far as i know anyways.

 

[Snoranger]

Last, I want to keep the manual tranny, and with the admittedly little research I have done on it seems as though the automatics are the only option. Please don't berate me for the last point. It may not be acurate, but with the other points listed I haven't bothered to find the answers to be sure. It wasn't worth the time to reseach it fully.

If you go with the 4.0l and want a manual, you want the M5OD-R1. It the only stock manual option that will bolt right up and hold up to the power.

 

[Bennybooster]

You can definitely put a manual behind a v8 in your truck

 

[MJ'sBlkBII]

Thanks, I know the 302 had a manual option in both the Mustangs and F-series, it just seemes to me that the auto is the choice when swapping in the RBV's. Perhaps because of the transfer case? I dunno.
Here is more circling: If I do the 4.0 I don't want to do the gears since it will have the power and the gears will be counter intuative to the build.
Luckily I have untill next April to decide or find a 4.0 since that is when I'm taking my next 2 week vacation, and funds will be available for whatever direction I go.

 

[Snoranger]

Thanks, I know the 302 had a manual option in both the Mustangs and F-series, it just seemes to me that the auto is the choice when swapping in the RBV's. Perhaps because of the transfer case? I dunno.

Your best options to go V8/stick:
M5OD-r2 (2wd or 4WD) 5spd
ZF-S542 (2WD or 4WD) 5spd
T5 (2wd only, unless you can find the no longer produced AA adapter) 5spd

The M5 and the ZF are the best choices. They are set up for hydro clutches already.


Then you get into the 4 speeds.
t18
t19
np435
toploader

Any of which can be used.