MY build thread...'88 Bronco II Desert Rat Patrol Edition: 1/26/24 update!

[Northidahotrailblazer]

when comparing the 2.9 vs the 4.0 you cant look at the horse power. The torque is where the big gain is. 2.9 140 hp/170 torque vs 4.0 160 hp/220 torque. Thats where its at. The torque will help you over the hill, not the hp. heads and a cam in a 2.9 aren't going to help much.

Its a rabbit hole of time and money. If I was in your shoes, Id just drive it enjoy it and plan for your next swap.

Going to 456s gears would help give you some power feel back, but I don't even know if you can buy 456s for a D28 still. Might as well upgrade to a D35 front axle and 8.8 rear. Rabbit hole again. haha

 

[Peter Griffin]

when comparing the 2.9 vs the 4.0 you cant look at the horse power. The torque is where the big gain is. 2.9 140 hp/170 torque vs 4.0 160 hp/220 torque. That's where its at. The torque will help you over the hill, not the hp. heads and a cam in a 2.9 aren't going to help much.

Its a rabbit hole of time and money. If I was in your shoes, Id just drive it enjoy it and plan for your next swap.

Going to 456s gears would help give you some power feel back, but I don't even know if you can buy 456s for a D28 still. Might as well upgrade to a D35 front axle and 8.8 rear. Rabbit hole again. haha

I get the relationship between HP and torque and I try not to bench race dyno sheets, etc. I always love it when guys add up the HP/torque gains on the box of the stuff they bought, add that to the factory rating and then state their "new" power ratings...

I have a mild/modest body and suspension lift; 2-inch blocks and what Skyjacker calls their 1.5-2-inch lift kit. With my front and rear zombie bumpers and 31-inch tires I've added a bit of aero drag, rotating mass and overall weight, so the way it's performing really isn't a surprise to me, and I'm not disappointed, I'm just finally getting to drive/test it with everything near wrapped up and figuring out what I'm going to do next...

I'm not sure a gear swap is even doable like you said, and I'm not going to swap axles either. Even if I could I'm not sure how my tire size/gearing/engine speed would all line up and solve my interstate speed requirement, and could actually make it worse.

Like I said in my first post from Jump Street I need it to do two things well/decently; get me around town (including the interstate with a 75 MPH speed limit) and let me putt around in the desert without (1) the truck overheating or (2) the occupants doing likewise! The more specialized you build a vehicle for one purpose, the more it sucks at doing another...which is why when I wanna go REALLY fast and need to get somewhere...I get in this:

 

[Bronson with Bronco]

Going to 456s gears would help give you some power feel back, but I don't even know if you can buy 456s for a D28 still. Might as well upgrade to a D35 front axle and 8.8 rear. Rabbit hole again. haha

I can confirm that 4.56 gears are no longer available for the D28. I found a local listing last year for someone selling a broken D28 that had the 4.56 ring and pinion, so swapped it into my 84 as a cheap solution to the underwhelming 2.8L power. Sometime later in 2024 I plan to swap in the axles from the donor Explorer, after the 4.0 swap is complete and we drive it for a bit. The gearing made a world of difference getting around in our hilly part of the world.

 

[lil_Blue_Ford]

So… I’ll throw out some thoughts…

My Choptop I ran 4.10 gears and 33” tires with a 2.9 and FM-146 manual transmission. It did ok, but it wasn’t really happy about it. When I went to 35” tires with a healthy 2.9, first through third it pulled hard and then fell flat on its face when you hit 4th. My only real upgrade was to do the larger throttle body that was on the EGR equipped 2.9 motors. Since it was an 89, I threw a 4.0 in with headers and called it a day. Well, it’s actually ate a number of motors over the years, think the current 4.0 is #4 for the 4.0 and #8 overall, but that’s another story. Honestly, it could still use a little deeper axle gear or a little more engine or a bit of both. It works well enough for now though.

My 88, well, I tried doing a 4.0 swap way back when and never finished it. Back then when I tried it I didn’t know what I do now and there wasn’t much information on the swap, even on here. Bear in mind, we are talking like 2003/4-ish. I ended up pulling out what I had put into it when I did the 4.0 in my Choptop. Then my intention was to put the still running 2.9 from the Choptop in the 88 with a little love. Other things got in the way and I never finished that experiment yet.

For a couple years of college I had an 89 B2 that was the same as my 88, Eddie Bauer package, power everything, automatic, etc. It was a real dog when I got it but after a tune-up and all it did ok. I always blamed the transmission. Now I’m not entirely convinced. My 92 Ranger and even my 2000 Ranger (the green one) had 4.0 motors with auto transmission and neither was impressive. I eventually ended up doing valve body work to the 92 and it was an animal after that, so I’m curious to see what it does for my 88 B2, so I’ve added that to my list of what I want to do to the 88.

My plan for the 88 was to do a gasket-match port job (minimum, ideally a flow port job would be best), headers, the bigger throttle body, convert to MAF over the original Speed Density system, maybe a cam, free-floating rockers, e-fan, electric power steering, upgrade the alternator, potentially a supercharger, and the transmission work. 30-31“ tires. See where that gets me.

The biggest hurdle with the 4.0 OHV swap is the wiring. You either have a ton of splicing to do or you get the dash and dash harness out of an 89-94 B2 or Ranger. Ranger will be your donor most likely. Not sure how different the Explorer dash and harness may or may not be. Also, you will probably want a 90-92 Ranger donor, the 93/94 had the same dash but the computer may have moved to the cowl in those.

 

[Angry Possum]

Picked up my wheels/tires (set of 5) from Discount Tire today! Alignment is scheduled for next Wednesday and should have my AOR rear bumper delivered on Saturday. Still grinding away (literally!) on the interior...

View attachment 93736

What's the tire size? They look like 31's.

 

[Peter Griffin]

What's the tire size? They look like 31's.

To quote Ed McMahon, as he would say to Johnny Carson...

You are correct Sir!

 

[Peter Griffin]

Update...

I have a love/hate relationship with e-fans honestly. While my experience is anecdotal of course, the last time I tried one it almost burnt my vehicle to the ground and left me stranded on a cross country trip with my wife, two kids and a trailer full of very expensive custom motorcycles. It turned out the wiring/relay kit that came with the fan (Flex a Lite, full disclosure) used substandard/Chinesium wiring which nearly turned into a full on electrical fire on the side of the interstate had I not been paying attention. Call me crazy but I kept the stock engine driven fan in the trailer with my tools so I was able to get back on the road relatively quickly. That happened 15 or so years ago but I remember it like yesterday as soon as I hear the term "e-fan".

That being said my search, nay, QUEST for MOAR POWAH needed to start simple/easy, and having driven my truck a short distance in cooler weather with the engine driven clutch/fan off the difference is significant. The amount of drag on the tiny 2.9 (which is only 1/2 liter bigger than the supercharger ONLY on my Hellcat! ) is noticeable the second you take it off, I just needed to figure out the whole e-fan deal...

I already had one e-fan pusher (from a MB AMG) on top on my A/C condenser with the Dakota Digital fan controller (which can control two separate fans) so with some help from @gaz I grabbed a Flex a Lite model 188. I initially had some fitment issues with both width and the A/T cooler lines and was about to pack it in when Gaz, unquestionably channeling Occam's Razor, suggested inverting it to see if it fit that way. It did, mostly, albeit with the A/C cooler lines still not tickled about it, but when I take my truck in to have it's 500 mile transmission rebuild tune up they're going to fix the (hard) lines for me and properly route them around the fan's shroud.

I don't think I mentioned it but my MTX powered subwoofer inexplicably stopped working so Crutchfield promptly replaced it and now I'm on my THIRD one, the first one being DOA. You can't make this crap up, but since it's under warranty I can't complain, and it's easy enough to swap it out, it just doesn't exactly fill me with confidence that this one is going to be any better.

ANYWAY, in addition to the fan I added a drop-in K&N filter and was off for a quick (pun intended!) road test. While it was noticeably quicker and wasn't revving/struggling the way it was before, when it came time to test it through the pass near my house it wasn't much faster and still dropped below 55. I wasn't expecting it to rocket over it @ 60+ but I was hoping for a little better performance.

That being said I need to check the timing, and Gaz has an excellent method using a vacuum gauge that I'm gonna try. It's running PIG rich and getting awful mileage so I'm not sure my mechanic set it properly when I asked him to. Again, I'm not expecting anything over the top, but I need to make sure that's correct before I take it a step further, if I'm even going to bother doing that or stand pat where I am and be happy for lack of a better term!

 

[Peter Griffin]

I'm still plugging away here...couple of updates, long story short it's still a work in progress!

Transmission shop (pity you can't say "tranny" shop or fluid anymore...anyway...) wanted it back for a 500 mile checkup. I was fairly certain from my driveway that it had a very mild leak of some type, looked like from the pump seal, and it did. When I asked about them cutting/running new cooler lines to help me out with the new e-fan they were more than happy to, and suggested a cooler upgrade while they were at it. I figured why not and told them to do it, just kind of curious why they didn't offer/ask about that the first time around, but with our extreme heat, whatever...

I discovered another issue that I brought to their attention that they looked into, and of course, it turned into something else...! They obviously had to remove the exhaust system to completely drop the transmission and I noticed that it was rattling, which, after checking it out myself, I thought was attributed to them reinstalling it improperly. Of course I was incorrect...

I did notice that not only am I running quite rich but my brand new catalytic converter has obviously been heat cycled, to put it mildly. I won't make anyone go way back in this thread but when I first bought this truck it had the converter deleted, a Cherry Bomb muffler, exhaust exited in front of the rear wheel, it had more leaks in it than the Oceangate Titan mini sub (too soon?) and of course, stunk to high Heaven. From the sounds of it, the substrate is cooked. They're gonna pull it and take a look at it, and in the interim throw in a test pipe. While I don't have emissions testing where I live I'm NOT a fan of permanently removing the converter, but I'm also not a fan of buying another one and smoking that one in around 1K miles of driving either. When I get it back I'll figure out the timing issue (if there even is one) and get to the bottom of the over rich condition, which explains the poor mileage and low power...

A clogged converter would also explain the loss of power too of course. When I first bought it, it had no problem ripping down the highway at near 80, which in hindsight was near suicidal, and my new 31s and zombie bumpers really shouldn't have a dramatic effect, so that may be the issue.

I need to hash all of that out before I decide on whether or not to get some new/upgraded heads while I'm at, but one thing at a time!

 

[scotts90ranger]

Melting catalytic converters is NOT from running too lean or rich, it is from unburnt air/fuel mixture, just running rich means there's more fuel than can burn with the air available, leaner is hotter but not to the extreme of cat melting unless taken too far (cat substrate melts at around 900C). The biggest cause is misfires from bad spark plugs, wires or cap or one bad injector tricking the O2 sensor.

 

[bobbywalter]

 

[Peter Griffin]

Melting catalytic converters is NOT from running too lean or rich, it is from unburnt air/fuel mixture, just running rich means there's more fuel than can burn with the air available, leaner is hotter but not to the extreme of cat melting unless taken too far (cat substrate melts at around 900C). The biggest cause is misfires from bad spark plugs, wires or cap or one bad injector tricking the O2 sensor.

It has new cap, rotor, coil, wires, plugs and an O2 sensor...not sure if there's any injector issues so that's something else I can take a look at. I'm just spitballing at the moment as it's sitting in the transmission shop waiting on a seal for the transfer case that went south on the rebuild and was discovered during reinspection. I'm not even sure the catalytic converter is cooked; just that the rattling is internal which in my experience is from the substrate getting fried/clogged. It's all rather frustrating and has been a lot of push down on one problem over here and another one pops up over there but if it was easy everyone would be doing it!

 

[Peter Griffin]

UPDATE! And, as usual, a mixed bag...

I brought it back to the transmission shop for it's break-in/warranty check up (it did have a leak...) and asked if they would cut me some new transmission cooler lines (where they go into the driver's side of the radiator) since they weren't happy with the new e-fan shroud/assembly I had wedge between them and the radiator. I also asked them to check the exhaust/catalytic converter since they had to remove it to service the transmission and it was now rattling...

When they called and told me the exhaust noise was coming from INSIDE the catalytic converter, I had 3 options. Remove it and send it back to Rock Auto for a warranty replacement (request, no guarantee), gut it or replace it with a test pipe. Since I wasn't sure what the issue was and have had issues with Rock Auto, never mind the shipping cost to send it back, I told them to either gut the converter or replace it with a test pipe.

The leak was apparently coming from the transfer case and they had to wait for a seal which was backordered so my truck sat for a while. They called me the other day and said it was ready so I picked it up yesterday.

The gentleman that did the exhaust said the converter was wrecked (internally). Apparently the substrate on the rearmost assembly came loose and had twisted/shifted sideways so it was effectively blocking the exhaust. The substrate in the forwardmost assembly had broken loose from it's mount/welds and shifted back several inches, which he possibly attributed to the massive increase in back pressure from it being nearly completely blocked. So, effectively it was a mechanical defect with the converter itself that was causing me performance issues, NOT the running condition of the motor itself and frying/clogging it. I asked, rhetorically, if that would cause performance issues and got the response I thought; of course it would, the motor was being choked by a significantly restricted exhaust.

That was "good" news...I guess? I was looking forward to taking it through the pass as a test to see what kind of difference it would make, if any, and jumped on the interstate. After going through it eastbound, which has a much more mild grade, I took the off-ramp and flipped a u-turn to go east bound and started on a significant grade at approximately 15 MPH. Slowly but surely it pulled to just over 65 MPH and at the steepest part of the grade, where it completely fell on its face and could barely hold 50 MPH it dropped to JUST under 65 and was hardly struggling.

So I went through the same elevation/pass at almost 15 MPH faster than before. I'd call that a win and say the converter was absolutely the cause of the issue. I'm likewise positive that its effect on my gas mileage was pretty significant too, time will tell on that.

I took my usual desert shortcut and it ripped through it like it's never done before, which made me wonder how long the converter has been defective/acting up. When I went to exit the desert and get back on surface streets the 4WD button on the overhead console, which has ALWAYS been janky, got stuck inside, and even after prying it out with my knife would not reset in its proper position...UGH!

So when I got home I started futzing with that and it did NOT want to come out. I don't know if one of the springs came out of position or what, but it's never been particularly solid. I MIGHT convert to manual axles and just be done with messing with that. There's no issue with the Low Range button...at least for now!

I then went into my glovebox to put my receipt in it and an aquarium spilled out onto my floormats. We had several days of torrential, near Biblical rain here and there's obviously a leak somewhere that I need to chase, so that's on the list now even though we rarely experience rain here, I still need to see if I can figure it out...

I didn't further inspect it until later when I wanted to see the handywork on the new transmission cooler and lines. The new cooler is a very nice and rugged looking B&M unit I believe, and as soon as I popped the hood I realized they hadn't touched the cooler lines. WTF...

I called the shop and spoke to the manager who originally did my drop off paperwork. The techs/mechanics had gone home for the day, now I'm just waiting for a call back. So now I'm gonna have to drop it back off for work that should have been done the first time, and wait...

I stopped by my other local independent mechanic who I asked for an estimate to R&R my heads for a new set of sexy ones like @gaz and I were discussing. He hadn't texted me back because he's been busy AF and I'm waiting to hear back on that. Any delusions I had of doing that myself have recently gone completely out the window as I (re)injured my severely gnarly back (my lumbar vertebrae, L1-L5 are completely fused with 4 rods and 10 screws in addition to my left SI joint, NOT to mention several other significant orthopedic trauma surgeries...) and even this odds and ends stuff is gonna be a challenge...

Other than that everything is swell!

 

[gaz]

@Peter Griffin ,
Since you are testing your powerplant on the same pass with that much more vehicle speed control, you have really made some rewarding progress!! I didn't realize that type of reward until after:
• 15" electric fan
• K&N drop in
• all synthetic fluids
• 2¼" exhaust
• JBA headers
• fresh tune up

This also suggests that your gear ratio and tire size are a fuel economy friendly match

 

[gaz]

I'm very excited to learn your current fuel economy. This is a good time to reset your computer, if you haven't done it after all these changes.

 

[Peter Griffin]

I had to have my buddy that Raptor-lined the exterior wrap up some finishing touches, including fixing/sealing the passenger-side rain gutter rail that turn my glovebox and footwell into a fish tank! We don't get much rain here, but when we do it's pretty gnarly and with all the interior work I did that's unsat...so hopefully it's addressed!

Windshield and rear/side window moldings are freshened up too and I got my favorite stubby antenna (Cravenspeed) in place. I did have 2 of the 3 bolts holding one of the headlights in place completely back out, which is weird because they're under spring tension (?) but I caught it in time and got them replaced, but I do need to do a proper (re) alignment of them for night time driving. Still need to get the subwoofer volume control and rear view camera mounted...that's just me being lazy and I'm going to paint the window switch surrounds to match the interior paint I used on everything else, and recycle the metal framing the stock door panels use to mount those switches instead of the super janky screws the new door panels came with.

I STILL need to set/adjust the timing using @gaz's method; I'm actually not procrastinating...I've been dealing with the transmission and exterior paint/Raptor liner issue in addition with a new/significant back injury that's gonna require surgery here next month...so I'm trying to get stuff knocked out, believe me!