Cummins 4BT & Diesel Conversions Forums banner
361 - 380 of 387 Posts

·
Registered
Joined
·
536 Posts
Discussion Starter · #361 ·
I didn't realize how long it has been since I've updated.

I now have over 35k miles on the swap. Earlier in April I drove up to Indiana for a work trip and got the truck regeared while I was off working. Swapped from 4.56 gears to the 4.10 gears that come on the alpha model. Drives much better on the highway now. I stayed on the higher side of gearing to help transmission longevity at the expense of a little mileage. I run consistent 20 mpg tanks on the highway and can usually manage 19 around town. The combination of 35s, automatic, awd and the aerodynamics of a small barn limit my mpg potental.

I also got the ac completed late in the summer which was the last major subsystem to get completed.

The truck has been largely trouble free lately. I need to upgrade the battery and cables for winter time. This has been on the to-do list for a while.

 

·
Registered
Joined
·
1,753 Posts
What part of Indiana did u come to? I would have loved to check out your build in person. Sounds like it's going good
 

·
Registered
Joined
·
536 Posts
Discussion Starter · #363 ·
Finally got around to setting up a dual battery. I ended up using two standard group 34 batteries, as this is a popular upgrade setup in the H3 paltform. I have always had good luck with standard batteries (not exotic or agm types) so decided to stay with the same here to keep cost down. Both batteries were under 200 total with my single core exchange. Thats 800 CCA x 2. Should have no problem in winter time.

I fabbed a tray from some light angle and flatbar to fit the two smaller batteries lengthwise.



Two threaded rod couplings are bolted to the flatbar from underneath. A threaded rod will screw in from the top.

Here is the tray tacked down in place. I hope I don't regret welding it. If you look at that picture, the only way to change the power steering pump is to get it out the top. The last time I had to work on it, it was a chinese puzzle to rotate it to get it out. I'm not sure it will pass now. If not I'll have to grind the tack welds to get the tray out.



Here you can see the rod couplings and how they fit right around the battery and serve as a center guide and keeps the two battery bottoms in place.



And here it is with the top clamp in place. With the threaded rods from the center, you can get a nice clamping force on the batteries. Its solid as heck. No movement in the tray whatsoever.



Finished product with terminals and cross connections.

 

·
Registered
Joined
·
478 Posts
Very nice set up. Thanks.
 

·
Registered
Joined
·
565 Posts
OK, got the alternator mount fully fabbed and test fitted. I need an opinion on the belt wrap. This photo is with an 86" belt. The tensioner is in the second half of its rotation. It seems like more rotation gives higher tension. Should I keep this here or go with a 1" longer belt to increase the wrap on the fan pulley at the expense of belt tension?

How has this AC setup worked out? is that enough belt on the crank pulley?
 

·
Registered
Joined
·
4 Posts
With the throttle body back in the installation, do you think there's a chance you could have let the stock PCM control the trans? I can see how, when you were starting out, the haziness of the future of the electronic controls of this project would have suggested the separate controller as the way to go, but I'm just wondering if you've reconsidered that point in hindsight.
 

·
Registered
Joined
·
4 Posts
One other question, how are you getting vacuum to the brakes? I see you referenced a Cummins power steering pump earlier, and that you're not driving a PS pump off the serpentine... are you running the 6BT power steeering + vacuum pump?

Edit: I see you referencing possibly having trouble getting the PS + vacuum pump out from under the battery tray so I'm assuming that's a Cummins setup.
 

·
Registered
Joined
·
536 Posts
Discussion Starter · #369 · (Edited)
Let me see if I can answer all of these questions.

The belt configuration works OK. It tends to squeal if I kick the ac on right after I start it. If I wait a second it works just fine. I assume its the load on the alternator and the ac combined. The factory tensioner is in the wrong place, it needs to be last right before the crank pulley. I want to maybe try a static tensioner or a travel limiter on the factory one.

I think in theory the factory ecu could control the trans. However, I do not know how many inputs influence shifting and if there are any engine parameters involved and if they could be suppressed. It would take a tuning software to re map the shift points at a minimum. The tuning software is more than I paid for the standalone controller.

Battery cables and cross connectors are all 4ga. Yes they are on the light end. I've run the single 640 CCA battery for 3 years with minimal issues. Low 30s is the coldest I've had to start it in. If I lived further north, this would likely be an issue for deep cold starts.

Brakes on the hummer are electronic assist. No vacuum or hydroboost needed. The braking module has its own controller and is integrated with the abs, stabilitrack and traction control. The power steering pump is just the standard spam can standalone gear driven type.
 

·
Registered
Joined
·
4 Posts
I think in theory the factory ecu could control the trans. However, I do not know how many inputs influence shifting and if there are any engine parameters involved and if they could be suppressed. It would take a tuning software to re map the shift points at a minimum. The tuning software is more than I paid for the standalone controller.
That makes sense, I would guess also that a standalone controller is probably easier than trying to figure out a tune in the stock PCM, especially given all the inputs from the motor side that it may or may not be looking for.

Brakes on the hummer are electronic assist. No vacuum or hydroboost needed. The braking module has its own controller and is integrated with the abs, stabilitrack and traction control. The power steering pump is just the standard spam can standalone gear driven type.
That's a pretty trick setup, I've been following closely because I have a Colorado but I did not realize that the H3's had a different booster vac setup.


Are you concerned at all about the steering rack under the weight of that motor? I haven't found solid weight numbers for the L52 but the 4BT might be closing in on double the weight. I've read that the 355 racks aren't the strongest. I already had to replace the rack mount bushings and went with a 355nation board sponsor's aluminum clamp mount setup.


That's a pretty sweet rig you've got, I subscribed to your thread to see if you have any updates or tweaks.
 

·
Registered
Joined
·
565 Posts
How has this AC setup worked out? is that enough belt on the crank pulley?
is your AC compressor in the same orientation as the original layout? Did you have to turn your AC compressor sideways?
 

·
Registered
Joined
·
3 Posts
I didn't realize how long it has been since I've updated.

I now have over 35k miles on the swap. Earlier in April I drove up to Indiana for a work trip and got the truck regeared while I was off working. Swapped from 4.56 gears to the 4.10 gears that come on the alpha model. Drives much better on the highway now. I stayed on the higher side of gearing to help transmission longevity at the expense of a little mileage. I run consistent 20 mpg tanks on the highway and can usually manage 19 around town. The combination of 35s, automatic, awd and the aerodynamics of a small barn limit my mpg potental.

I also got the ac completed late in the summer which was the last major subsystem to get completed.

The truck has been largely trouble free lately. I need to upgrade the battery and cables for winter time. This has been on the to-do list for a while.

What size tires and have you got intercooler yet?
 

·
Registered
Joined
·
1 Posts
If you ever want to part with it, please contact me. [email protected] or 910-212-2004. I love that truck and will be glad tocome to Indiana from NC to get it. Great build and just what I have been looking for. I am not a great mechanic myself, but I do appreciate all of what you have done with this H3. Please do contact me at any time if you would like to sell. Are you working on any other H3's. Thanks Much, James Elkins
 

·
Registered
Joined
·
536 Posts
Discussion Starter · #378 ·
Som updates on the project. I had the Hummer off the road for a little over 3 years. I had a wrist pin bearing go out and decided to do some other upgrades as the engine was rebuilt and put back in. On this list was 1) intercooling 2) upgrade to 6 speed transmission.

OK, finally finished my new cooling stack and got it loaded in the truck. I decided way back to intercool the engine once everything went back together. I researched a few cases to try and get an air to air unit, but there are several things that are just a no-go. First, there is not really that much room to get a core with sufficient thickness, 2.5" or 3". Second there is no good routing spot for the airflow tubing around the core support area, and third, I want to keep A/C so that still has to get figured into the equation. Also in this process, I ditched the factory radiator and went with an ECP 2 core. I ended up with a fabricated frame to hold the radiator and the water coolers. For the water coolers, I used a pair of TruCool 40k coolers. These cores are 1.25" thick and two fit up nicely to the face area of the radiator. I initially intended to mount the A/C condenser out front of this stack but I never could come up with anything that went together well or fit without pushing the whole thing back toward the engine. I ended up with a generic condenser from ColdHose. After test fitting, it was apparent that it would be easier to mount the condenser separate from the radiator and water coolers.

Here are the water coolers mounted to the front of the radiator and the bracket assembly,



And here is the backside showing the electric fan setup



I used a Derale fan controller that you can see mounted on the side of the frame. It uses a push in thermostat probe and basically runs as a standalone unit. I wired the turn on and override connections via a connector to my aux relay box which I had an ignition hot and a/c on wire already run there for that purpose.

Unit dropped in the vehicle



And then here a front view. Note how the condenser is mounted separately out front and then notice how the water coolers fit right snugly in the original width for the radiator.



I got the fan kickon point right at the mid line on my temp gauge so that's ready to go. I had to idle the engine almost 15 minutes just to get it warmed up enough to test. I'll do some follow reports once we get some miles on the setup.
 

·
Registered
Joined
·
536 Posts
Discussion Starter · #379 ·


For the transmission :

I have the front end worked out. This took some modifications to the flexplate. The torque converter bolt circle is slightly larger than the 4l60 so a quick buzz with a carbide burr to oval the holes fixed that. Second, the snout of the torque converter bottomed out on a step in the female side of the centerbore in the flexplate. When the crank was in for balancing, I had the machine shop remove the step so the centerbore goes all the way through. I am still plenty far enough from the snout bottoming on the crank.

For the back end I have a novak 6L81 universal adapter and I am getting a custom adapter donut to mount it all up. The novak unit is 3.25" long so a 075" thick plate with the proper drilling and a centering ring will allow it to all bolt up. I had previously had the 6l80e output shaft turned down to a 27 spline to fit the transfer case.

The wiring has a few challenges that I didn't expect from early research but no dealbreakers. Im using the PCS 2650 standalone and in the process of planning my wiring harness rework. The first major item is that the shift linkage on the 6 cannot mount the shift position indicator switches that the H3 uses. The indicator basically has 3 major circuits 1) a park/neutral switch for safe starting of the vehicle, 2) a reverse contact to power backup lights, and 3) a set of 4 switches used to encode the shifter position which is then communicated to the instrument panel. The 6 has an internal park neutral switch but its not an isolated contact. This will require a relay to isolate the signal. The 2650 has a reverse output which again is not isolated so a second relay will be required for reverse. The 4 encoded switches I'm afraid I will not be able to replicate. This means I will lose My PRNDL321 indication on the console. There are aftermarket gear indicators that plug right into the 2650 harness so if I want I will be able to display what I need, albiet not in an OEM fashion like I would prefer.
 

·
Registered
Joined
·
536 Posts
Discussion Starter · #380 ·
From the earlier posts, I got a friend to 3d print me a prototype adapter flange. His printer platen wasn't big enough to do in one piece so you can see its split in two halves. This is it bolted to the transfer case.

Name:  gAhw2tX.jpg Views: 108 Size:  1.51 MB


I ended up finding an orientation to get six studs in instead of the five. This adapter bolts to the transfer case with M10x25 socket head screws and you just move the transfer case studs to the flange. I kept enough material on the flange where they are counter sunk so you have to shave the bolts head by 1mm to clear flush. Here is the finished flange. I had the same friend make me a solid model file and I sent it of to Xometry. Cost was less that $250 for the flange and a centering ring

Name:  lkzJnmx.jpg Views: 107 Size:  1.81 MB


And bolted up with one of the studs installed. Note the second piece to this is a centering ring. This will keep everything centered when bolted up. It was much simpler to machine these to parts separate than to try and make a complex assembly as one piece.

Name:  Lnq9RwG.jpg Views: 107 Size:  1.25 MB


The "foot" for the mount is fabricated from a simple piece of 2"x3"x1/4" steel angle and is clamped in with the lower two studs on the flange. I do not have a good isolated shot of the foot.
 
361 - 380 of 387 Posts
Top