fidelity101
1/2 ton status
I already ordered the GM kit, the flexplate solution alone won't fix this because the pilot of the tqcv would bottom out in the crank before you could bolt the bellhousing together.
CK5
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2008 Suburban HD - 8.1L swap (frankenburban 2.0)
- Thread starter fidelity101
- Start date
fidelity101
1/2 ton status
So meanwhile with the downtime, I went ahead and started assembling what I could and get done what I needed to. I am a huge fan of chasing threads with a tap so everything bolts together nicely and without a fus. So I replaced the exhaust studs that were missing and chassed the remainders with a die, mostly because I couldn’t get them out.
With a help of a friend we cut down the stock harmonic balancer using a lathe, you have to have a chamfer on it so the reluctor wheel fits properly. Its about 1mm of a step, the OEM hub has a gradual step as well but likely to just not cut the front seal upon install. However the reluctor wheel has this opposite feature to accommodate it so it must be retained or clearance appropriately.
Then I got the flexplate back from the machine shop with the new pattern.
After that it was time to get moving so I started to get the engine together and install the harmonic balancer/oil pan/timing cover/water pump.
With a help of a friend we cut down the stock harmonic balancer using a lathe, you have to have a chamfer on it so the reluctor wheel fits properly. Its about 1mm of a step, the OEM hub has a gradual step as well but likely to just not cut the front seal upon install. However the reluctor wheel has this opposite feature to accommodate it so it must be retained or clearance appropriately.
Then I got the flexplate back from the machine shop with the new pattern.
After that it was time to get moving so I started to get the engine together and install the harmonic balancer/oil pan/timing cover/water pump.
fidelity101
1/2 ton status
Now its wiring time, the original wiring has a plastic sleeve that was all but brittle and collapsing so on a decent build you are ordering new hardware it helps to spend the extra 25 bucks and get some nice loom to protect everything so I wrapped the harness worth about 25’ worth and only have maybe 1-2 feet of wire uncovered. I didn’t bother to remove most of the plastic protection except where it was clearly deteriorating into pieces. This is a wrap around kind so I just tape it to keep it shut that way you are not fishing wire through the loom.
The wiring job for getting the gen III engine on Gen IV is pretty easy.
1. Re-locate knock sensor (passenger side)
2. Re-locate knock sensor (driver side)
3. New connector + lengthen CLT
4. Lengthen EVAP/alternator electrical connectors
5. CAM sensor – simplify wiring
6. CKP wire new connector
1. Passenger side knock sensor is the easiest but the wiring is a bit tight, not sure if I will need to extend this or not but the red hole is where the existing one was located (LQ4 have these in the valley of the V for some stupid reason so good luck with that). The thread boss nearby (circled red) is already tapped for m8x1.25 so I just hit it with the surface disc and chased the threads for a good contact. Existing knock sensor threads are a larger pipe thread, not sure about running a plug in there then drilling/tapping it but this seemed easier and maybe the knock sensor will perform more normal, just an assumption.
2. Driver side knock sensor is a little “harder” but same concept of moving it to the other boss however the boss is drilled and tapped for an m6 bolt so you need to get a 7mm drill or 17/64” and then re-tap it to m8x1.25 thread pattern, here there is a lot more wire length as well and clears behind the installed engine mount easily.
3. Electrically the CLT are the same but the ½” NPT is a bit hard to find adapters for so I just cut the connector and did my own 2 pin weatherpack. Since the ECU reads resistance like a DVOM the wires won’t matter which way you connect them. What is not shown is the harness lengthened, I think it needs a few more inches for routing purposes and not melting it with the exhaust manifold.
4. These are the easiest, two 2 pin connectors need about 4-6” length increase.
5. The cam sensor is the same connector but because my LY6 had VVT they have a 5 pin connector, you don’t need this anymore so I cut the wires and hid them in the loom. The wires are too long with this setup too so I cut the extra wire length and omitted the connector (circled in green). If you want to keep this harness section intact you can just junkyard a new pigtail or order one online.
6. Here is the “hardest” wiring job, the crank connector is totally different and in a different location, you need to shorten the wires and then hookup the correct wires to the new connector, luckily they are the same orientation (lock mechanism upward when connector facing you) so wiring is pretty easy
Here is the new connector, you can find this in the junkyard off of a 4.3L from an S10 or blazer etc actually, colors may be the same – not sure on that part but I got this pigtail online for about 20 bucks.
(LY6 connector to new58x connector)
· Pin A to Pin 3 (white wire with black trace)
· Pin B to Pin 2 (grey wire with black trace) (ground)
· Pin C to Pin 1 (purple wire with white trace)
They are both wired the same and electrically the same with the same wire colors just the connector naming is reversed…
So with that all done it was time to install the spacer kit, it came with longer dowels and a bellhousing flange.
I was afraid that spacing the engine 10mm forward would mess up the engine mount alignment but I undid the trans mount that allows some forward/aft movement and was able to eat up this gap with that slotted tolerance in the crossmember and push the transmission backwards in vehicle a touch. A bit of wiggling later and careful guidance and the engine was mounted in without having to modify the stock mounts in any way shape or form. It is currently bolted down.
Now I just need to verify if the spacers provided are enough because I do not want to grenade a transmission or tqcv. I want to double/triple check this area before I go further with installing everything else just in case I need to remove the engine again.
The wiring job for getting the gen III engine on Gen IV is pretty easy.
1. Re-locate knock sensor (passenger side)
2. Re-locate knock sensor (driver side)
3. New connector + lengthen CLT
4. Lengthen EVAP/alternator electrical connectors
5. CAM sensor – simplify wiring
6. CKP wire new connector
1. Passenger side knock sensor is the easiest but the wiring is a bit tight, not sure if I will need to extend this or not but the red hole is where the existing one was located (LQ4 have these in the valley of the V for some stupid reason so good luck with that). The thread boss nearby (circled red) is already tapped for m8x1.25 so I just hit it with the surface disc and chased the threads for a good contact. Existing knock sensor threads are a larger pipe thread, not sure about running a plug in there then drilling/tapping it but this seemed easier and maybe the knock sensor will perform more normal, just an assumption.
2. Driver side knock sensor is a little “harder” but same concept of moving it to the other boss however the boss is drilled and tapped for an m6 bolt so you need to get a 7mm drill or 17/64” and then re-tap it to m8x1.25 thread pattern, here there is a lot more wire length as well and clears behind the installed engine mount easily.
3. Electrically the CLT are the same but the ½” NPT is a bit hard to find adapters for so I just cut the connector and did my own 2 pin weatherpack. Since the ECU reads resistance like a DVOM the wires won’t matter which way you connect them. What is not shown is the harness lengthened, I think it needs a few more inches for routing purposes and not melting it with the exhaust manifold.
4. These are the easiest, two 2 pin connectors need about 4-6” length increase.
5. The cam sensor is the same connector but because my LY6 had VVT they have a 5 pin connector, you don’t need this anymore so I cut the wires and hid them in the loom. The wires are too long with this setup too so I cut the extra wire length and omitted the connector (circled in green). If you want to keep this harness section intact you can just junkyard a new pigtail or order one online.
6. Here is the “hardest” wiring job, the crank connector is totally different and in a different location, you need to shorten the wires and then hookup the correct wires to the new connector, luckily they are the same orientation (lock mechanism upward when connector facing you) so wiring is pretty easy
Here is the new connector, you can find this in the junkyard off of a 4.3L from an S10 or blazer etc actually, colors may be the same – not sure on that part but I got this pigtail online for about 20 bucks.
(LY6 connector to new58x connector)
· Pin A to Pin 3 (white wire with black trace)
· Pin B to Pin 2 (grey wire with black trace) (ground)
· Pin C to Pin 1 (purple wire with white trace)
They are both wired the same and electrically the same with the same wire colors just the connector naming is reversed…
So with that all done it was time to install the spacer kit, it came with longer dowels and a bellhousing flange.
I was afraid that spacing the engine 10mm forward would mess up the engine mount alignment but I undid the trans mount that allows some forward/aft movement and was able to eat up this gap with that slotted tolerance in the crossmember and push the transmission backwards in vehicle a touch. A bit of wiggling later and careful guidance and the engine was mounted in without having to modify the stock mounts in any way shape or form. It is currently bolted down.
Now I just need to verify if the spacers provided are enough because I do not want to grenade a transmission or tqcv. I want to double/triple check this area before I go further with installing everything else just in case I need to remove the engine again.
Looks familiar... I did the same redrill to fit my gen v bbc to my 700r4.
So meanwhile with the downtime, I went ahead and started assembling what I could and get done what I needed to. I am a huge fan of chasing threads with a tap so everything bolts together nicely and without a fus. So I replaced the exhaust studs that were missing and chassed the remainders with a die, mostly because I couldn’t get them out.
With a help of a friend we cut down the stock harmonic balancer using a lathe, you have to have a chamfer on it so the reluctor wheel fits properly. Its about 1mm of a step, the OEM hub has a gradual step as well but likely to just not cut the front seal upon install. However the reluctor wheel has this opposite feature to accommodate it so it must be retained or clearance appropriately.
Then I got the flexplate back from the machine shop with the new pattern.
After that it was time to get moving so I started to get the engine together and install the harmonic balancer/oil pan/timing cover/water pump.
fidelity101
1/2 ton status
correction, the 1st knock sensor post, the orange circle is the one that is m8 already.,
did it work out okay for you? any issues?
did it work out okay for you? any issues?
Looks like everything is working out, the redrill looks good. You have a ton of good information in this thread. I saw a sweet GMT900 duramax burb this weekend on the highway going down to Utah. Didn't have time to get a pick though.
It's been fine so far.
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Cool! Things are coming along nicely….the 8.1 looks at home in there. I didn’t realize your engine was a reman until you posted pictures of it. Curious of the coins epoxied to the head indicate who the remanufacture was?
For what it is worth, PSI mounts those type knock sensors to the back side of the cylinder heads on the 8.8L (weird yes, but that is where they put them). I looked for a picture to show you but unfortunately, I don’t have one. Might be able to snap a picture of an 8.8L tomorrow. That location cleans up and wiring under the engine with two less things to get cooked by the exhaust but you would need to extend the leads by a foot or so if you wanted to move them.
For what it is worth, PSI mounts those type knock sensors to the back side of the cylinder heads on the 8.8L (weird yes, but that is where they put them). I looked for a picture to show you but unfortunately, I don’t have one. Might be able to snap a picture of an 8.8L tomorrow. That location cleans up and wiring under the engine with two less things to get cooked by the exhaust but you would need to extend the leads by a foot or so if you wanted to move them.
fidelity101
1/2 ton status
It is not a reman, thats the junkyard that puts like a turkey cooker popper on it so if you overheat it they can void the warranty if I try and return it.
The engine mounts have heat shields and the driver side knock sensor wiring runs low enough where its not an issue, we should be okay with the locations chosen currently.
fidelity101
1/2 ton status
Now the moment of truth, the tqcv spacers provided are 7mm whereas the bellhousing spacer is 9.6mm, this should give proper tqcv clearance, and it did! We have a 6mm gap with the tqcv full seated which is good enough to pull it forward without it disengaging the pump drive and breaking a transmission/tqcv.
The rest is just assembly for the most part, re-assemble everything but once that occurs I need to worry about the tune, kinda curious just to start it up and see if it will idle, I don’t see why not but I am not familiar with HP tuners. I have a few resources available but has anyone tried to overwrite a tune? I mean I would unlock the VIN/ECU for the truck but then can I just download/upload the stock L18 tune to the PCM? Or am I better off manually inputting these values. IE since the TCM is separate on the gen III LS stuff I wonder if it will get all wonky. The other thing is the torque messaging for torque managing the clutch to clutch shifts and shift points etc, this will need to be adjusted independently. Long story short, I don’t know anything about HP tuners other than everyone uses it.
Some progress however, I do need to take the harmonic balancer off again though to get the rust off of the shaft where the seal rides, (now that I’ve shortened it) I neglected to clean this up enough and I don’t want to do a front main seal job after the front clip is assembled and etc. I really hate using the harmonic balancer install tool. ..
The rest is just assembly for the most part, re-assemble everything but once that occurs I need to worry about the tune, kinda curious just to start it up and see if it will idle, I don’t see why not but I am not familiar with HP tuners. I have a few resources available but has anyone tried to overwrite a tune? I mean I would unlock the VIN/ECU for the truck but then can I just download/upload the stock L18 tune to the PCM? Or am I better off manually inputting these values. IE since the TCM is separate on the gen III LS stuff I wonder if it will get all wonky. The other thing is the torque messaging for torque managing the clutch to clutch shifts and shift points etc, this will need to be adjusted independently. Long story short, I don’t know anything about HP tuners other than everyone uses it.
Some progress however, I do need to take the harmonic balancer off again though to get the rust off of the shaft where the seal rides, (now that I’ve shortened it) I neglected to clean this up enough and I don’t want to do a front main seal job after the front clip is assembled and etc. I really hate using the harmonic balancer install tool. ..
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Well, that is probably a good thing it is not a reman as I handle the UPS account for Navistar where they have a little over 1,200 8.1L package cars and the remans they have gotten as of late have been less than sterling. Regarding the engine mounts, I have mixed emotions about the heat shields. GM had good intentions of protecting the rubber from exhaust manifold heat but there is one school of thought where the head shield actually hold the heat in and bakes the rubber. None the less, GMT800’s eat engine mounts like mad. Small blocks and 8.1L’s alike. I just replaced the engine mounts in my 2001 Silvy HD 8.1L last week with OEM replacements and the truck only has 68,000 original miles. I thought about leaving off the heat shields but reused them again so I am sure it will eat them again in another 16 years or 68K. 8.1Ls and Dirtymax GMT800’s used the same engine mounts and I kinda wished I would have looked to see what the aftermarket offers on the Dirtymax side for a better mount besides OEM. Something to consider before you do the final install
Sounds like you have a solid plan on the knockers but for the fun of it I was near a bus today with an 8.8L and got a few pics. Just think…. Years from now, we’ll all be looking at school buses to pirate engines from.
Passengers side rear of cylinder head. Driver’s side is the same. I won't lie, when I first saw they were mounting the knockers on the cylinder heads I thought they were crazy
fidelity101
1/2 ton status
I would love to run that accy drive, onboard air would be great for the beach/sand I do most of my wheeling in as well as power air tools for it's primary use as service vehicle. It looks like they polished the mold for the intake manifold, mine looks like a high school science project, you can see each layer like a poorly built cake. The bus has a smooth finish.
Funny you work with Navistar as I used to work at Meritor and Meritor WABCO.
Funny you work with Navistar as I used to work at Meritor and Meritor WABCO.
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You’re right, the 8.1L intake looks like a piece of aluminum painted styrofoam where you can see every tiny round ball of aluminum that was squeezed and baked together like a big rice crispy treat
. Speaking of the manifold, the 8.8L it is quite a bit different from the 8.1L as the injectors are located aright above the valve in the head rather than intake. 
This is actually a propane fuel rail but the gasoline is very similar
“LS” style rockers. The geometry has changed too... Finally!!!
Oil whizers that squirt oil under the pissers to help with oiling for low RPM operation. You can barely see the oil squirter in there.
Has rod bolts instead of studs and prevailing torque nuts. Not sure how I feel about this "upgrade"
Here is your 58X reluctor on an 8.8L that “should” (in theory) be able to be pressed on to an 8.1L crank
Back to regular scheduled GMT900 L18 tuning…. Just had to share those pics as they are so cool but you’d have to be a 8.1L guy to understand and appreciate them
Ya, we used a lot of WABCO ABS systems on Internationals and Workhorse trucks. I still deal with many Meritor guys.. mostly axle guys these days. Small world, but not so much for guys like you that live in the Detroit area.
I was a factory certified tech for an International dealer for ten years. I miss some of the cool stuff I would see there that would work good in the wheeling world.
Now the moment of truth, the tqcv spacers provided are 7mm whereas the bellhousing spacer is 9.6mm, this should give proper tqcv clearance, and it did! We have a 6mm gap with the tqcv full seated which is good enough to pull it forward without it disengaging the pump drive and breaking a transmission/tqcv.
The rest is just assembly for the most part, re-assemble everything but once that occurs I need to worry about the tune, kinda curious just to start it up and see if it will idle, I don’t see why not but I am not familiar with HP tuners. I have a few resources available but has anyone tried to overwrite a tune? I mean I would unlock the VIN/ECU for the truck but then can I just download/upload the stock L18 tune to the PCM? Or am I better off manually inputting these values. IE since the TCM is separate on the gen III LS stuff I wonder if it will get all wonky. The other thing is the torque messaging for torque managing the clutch to clutch shifts and shift points etc, this will need to be adjusted independently. Long story short, I don’t know anything about HP tuners other than everyone uses it.
Some progress however, I do need to take the harmonic balancer off again though to get the rust off of the shaft where the seal rides, (now that I’ve shortened it) I neglected to clean this up enough and I don’t want to do a front main seal job after the front clip is assembled and etc. I really hate using the harmonic balancer install tool. ..
The bellhousing spacer looks like it did the trick. How much was it?
You won't be able to use a 8.1 file on the later computer they are completely different computers. I don't think you will even be able to copy/paste any of the tables as they are quite a bit different, but I don't think it will be necessary to make many changes. You will need to input the injector size (if different), the cylinder size, disable the VVT and DOD and related codes before you start it. Everything else will likely be close enough to run and drive. Make sure and adjust the shift points in the trans controller as they will likely be a little higher than the 8.1 will like. The MAF table will probably need some work at the upper end of the scale depending on how much more air the 8.1 moves compared to the LS.
fidelity101
1/2 ton status
The whole kit was 285 but I didn't use the flexplate and most of the hardware because they were not metric. I got part numbers now for the required pieces, I'll post them later. The injectors are the same size, looks like just disable VVT and this engine doesn't have DOD. I do have a dual ( 2 banks ) wideband to use when tuning to so that should be no issue.
fidelity101
1/2 ton status
Making progress during the re-assembly should be fully put back together this weekend then ready for a tune.
PRO TIP #1: Install trans dipstick BEFORE putting the engine in while the trans is lowered, it is much easier. No wait - its physically impossible to do it if you don't. I cut the bracket off where it attached to the back of cyl head so I can install it while the engine is in the vehicle. real big PITA.
PRO TIP #2: connect the oil pressure sensor before you put it in the engine bay, or at least before you connect the driver side cat/exhaust. not impossible but unnecessarily difficult.
Trying to assemble everything from the rear forward, but I wanted to get this low hanging fruit out of the way: A/C compressor.
Funny thing is this is the same part number for AC compressor as the 6L, but I can't seem to find a photo where they bolt up this 4th hole in any photo...
so I made a bracket just in case.
PRO TIP #1: Install trans dipstick BEFORE putting the engine in while the trans is lowered, it is much easier. No wait - its physically impossible to do it if you don't. I cut the bracket off where it attached to the back of cyl head so I can install it while the engine is in the vehicle. real big PITA.
PRO TIP #2: connect the oil pressure sensor before you put it in the engine bay, or at least before you connect the driver side cat/exhaust. not impossible but unnecessarily difficult.
Trying to assemble everything from the rear forward, but I wanted to get this low hanging fruit out of the way: A/C compressor.
Funny thing is this is the same part number for AC compressor as the 6L, but I can't seem to find a photo where they bolt up this 4th hole in any photo...
so I made a bracket just in case.
Well, that is probably a good thing it is not a reman as I handle the UPS account for Navistar where they have a little over 1,200 8.1L package cars and the remans they have gotten as of late have been less than sterling. Regarding the engine mounts, I have mixed emotions about the heat shields. GM had good intentions of protecting the rubber from exhaust manifold heat but there is one school of thought where the head shield actually hold the heat in and bakes the rubber. None the less, GMT800’s eat engine mounts like mad. Small blocks and 8.1L’s alike. I just replaced the engine mounts in my 2001 Silvy HD 8.1L last week with OEM replacements and the truck only has 68,000 original miles. I thought about leaving off the heat shields but reused them again so I am sure it will eat them again in another 16 years or 68K. 8.1Ls and Dirtymax GMT800’s used the same engine mounts and I kinda wished I would have looked to see what the aftermarket offers on the Dirtymax side for a better mount besides OEM. Something to consider before you do the final install
Sounds like you have a solid plan on the knockers but for the fun of it I was near a bus today with an 8.8L and got a few pics. Just think…. Years from now, we’ll all be looking at school buses to pirate engines from.
Passengers side rear of cylinder head. Driver’s side is the same. I won't lie, when I first saw they were mounting the knockers on the cylinder heads I thought they were crazy
Mmmm 538 cubes of V8 goodness. With awesome accessory setup to boot. Very nice.
fidelity101
1/2 ton status
More progress assembling everything, the core support is back on and a lot of the little other tid bits, wiring is hooked up. There is one hang up on the cooling system though. I did opt for the 8.1 radiator/cooling system entirely but it was not as plug and play as I thought.
PRO TIP #3: when using the AC delco radiator it needs the AC delco lower radiator hose, on the radiator end it uses a large quick disconnect fitting like the oil/trans cooler lines use. This radiator is cheaper than the other aftermarket radiator but the other radiators use a traditional lower radiator hose. So keep this in mind when ordering parts, in the end you will spend the same amount of money because the AC delco radiator is cheaper but the hose is more expensive, the other brand radiator is more expensive but the hose is cheaper.
Here is the 6.0 radiator in front of the 8.1 radiator, it is actually quite a bit larger in each dimension overall.
Because of this size you need to throw away the plastic spacer that the LY6 radiator uses to mount the rubber isolators of the radiator into the core support locator holes. The 8.1 radiator takes up this space so there is no need for this plastic component. Also these rubber isolators/locators are in different lengths center to center, the Ly6 is about 36 inches or so apart, whereas the 8.1 is 41 inches apart, a quick hole saw does the trick and you basically make a hole right next to where the core support gets bolted to the frame at the body mount location.
The core support is NOT the same between the two engines, however you can tell it was built on the same manufacturing assembly line as the both but they have unique part numbers so it is close enough.
Here you can see where there is a hole on the core support but no threads, a quick weld nut there and this lines up perfectly. The radiator sits in its new holes on the bottom and bolts right up to the top. And appears to bolt into the “factory” location.
Almost done with the swap, The only thing left is wait for the correct radiator hose to come in the mail then install the cooling fan/shroud, add fluids and put the fascia and lamps on then its ready for a tune and good to go!
PRO TIP #3: when using the AC delco radiator it needs the AC delco lower radiator hose, on the radiator end it uses a large quick disconnect fitting like the oil/trans cooler lines use. This radiator is cheaper than the other aftermarket radiator but the other radiators use a traditional lower radiator hose. So keep this in mind when ordering parts, in the end you will spend the same amount of money because the AC delco radiator is cheaper but the hose is more expensive, the other brand radiator is more expensive but the hose is cheaper.
Here is the 6.0 radiator in front of the 8.1 radiator, it is actually quite a bit larger in each dimension overall.
Because of this size you need to throw away the plastic spacer that the LY6 radiator uses to mount the rubber isolators of the radiator into the core support locator holes. The 8.1 radiator takes up this space so there is no need for this plastic component. Also these rubber isolators/locators are in different lengths center to center, the Ly6 is about 36 inches or so apart, whereas the 8.1 is 41 inches apart, a quick hole saw does the trick and you basically make a hole right next to where the core support gets bolted to the frame at the body mount location.
The core support is NOT the same between the two engines, however you can tell it was built on the same manufacturing assembly line as the both but they have unique part numbers so it is close enough.
Here you can see where there is a hole on the core support but no threads, a quick weld nut there and this lines up perfectly. The radiator sits in its new holes on the bottom and bolts right up to the top. And appears to bolt into the “factory” location.
Almost done with the swap, The only thing left is wait for the correct radiator hose to come in the mail then install the cooling fan/shroud, add fluids and put the fascia and lamps on then its ready for a tune and good to go!
This is awesome! Very nice work.
