L94 & 6L80 Into My '92 2dr K1500 Blazer

Long time lurker here; first post. I've studied this swap for about a year now and recently acquired a 2012 L94 6.2L with 5 miles on it. The 6L80 is out of an identically optioned 2012 Denali; it has 10K for mileage. The engine swap won't happen till probably March. I'm hoping to get most of the parts on hand and knowledge in my head before then. I'm hoping the swap itself won't take more than a month. (This won't be my first engine swap, but it will be my first LS swap.) My plan is to keep the motor and trans as close to stock as possible. My intent is to keep the BCM in the mix for cruise and "tow" mode.

I've owned the '92 since it was 6 months old. It's in pretty darned good shape, but the tranny is getting tired. I've already swapped in a freshly built 14 bolt SF rear end with an Eaton Trutrac. 3.73 gears. Once the engine swap is done, I'll redo the interior--although Infiniti G37 seats are going in this fall, before the engine swap--then I'll re-paint to finish it off.

My first question regards the 6L80. I understand it's about an inch shorter than the 700R4. I know most folks use 1" setback mounts to get the trans in the right place, but that won't be enough here. Is there enough room to put the motor far enough back to use stock driveshafts? If not, what setback is a good compromise for access to the rear of the engine? (I'll be using electric fans.) Also, has anyone dropped a LS motor with a 6L80 already attached into an OBS truck like this? If it fits easy enough, that seems like it would be a lot easier than getting the trans in place afterwards...

Thanks in advance for any and all advice!
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Okey dokey, I guess not much experience putting a 6L80 into an OBS truck here. I'll post what I learn as I go along to help the next guy out. :) Talked to PSwired--Patrick--from another forum. He's done the 6L80 into an OBS and graciously spent 30 minutes on the phone with me. Many thanks to him for his time and expertise.

I could maybe get the rod type shift linkage to work. (The '92 has rod linkage, the '95 has a cable shifter. Not sure which year is the changeover.) Doesn't seem like it's worth the effort at this point. I'll start out using an Ididit cable adapter for the stock column shifter, and possibly switch to a 2012 Malibu floor shifter with Tap up-down buttons later. I'm going to have Motech out of Vegas do the ECM programming and use their BCM setup for cruise control and tap up-down shifting. That'll keep everything as stock as possible.

I'm just here to learn! This is going to be an interesting swap....:tacos::tacos:

Thanks! Nothing too interesting will happen till March; that's when the swap begins. (Planned...) Right now I'm trying to amass information and parts. I have the engine & trans & complete set of GM service manuals for both the '92 and the 2012 now; trying to figure out the transfer case before buying one of those.

I'm thinking NP246 as the rig will only be lightly four wheeled. However, I have to figure out how the E38 ECM will figure out the transfer case is in low range. According to the Service manual the E38 looks at the VSS from both the 6L80 and the back of the transfer case, as well as getting a "low range" signal over the CAN bus from the transfer case. Of course, the NP246 can't send a message over CAN. I'm trying to find out if the E38 can be tuned to ignore the CAN bus signal and just use the speed signals. (BTW, the 6L80 has internal front and rear speed sensors--even for the 4WD version.) OR, does the trans shift based on it's own speed sensors? Does the E38 even need to know "low range" when paired with a 6L80?

Getting close! I have to finish my basement remodel first, should be done in a week or two. Then I can put away all of my wood working tools and get ready for the engine swap.

I'm sticking with the original NP241 Transfer case. Looks like I should just need a new input gear to match the 6L80. Measuring the 6L80 it's just about identical in length to my 700R4, so I should be good with the stock drive shafts and TC shift linkage.

I've collected most of my parts:
-Wire harness from Motech complete with BCM for stock cruise control, tap shifting and Tow mode.
-New Gas tank from a 1998 Yukon. That allows me to use a '98 fuel sender/pump. The '98 uses the correct resistance range for the fuel sender. It also has a fitting for a fuel tank vapor pressure sender.
-'98 fuel sender/pump assembly
-2001 Corvette Fuel Filter/pressure regulator
-2012 truck air cleaner/MAF/intake plumbing and electric fans
-motor mounts
-Holley AC brackets

Still need:
-IdidIt conversion to cable shifting.
-Fuel lines and fittings
-oil cooler & trans cooler & lines and fittings.
-EVAP setup.
-PCV catch Can
-input gear for the NP241

-Exhaust: Still undecided. I'm getting a bid for a complete exhaust from "Get Bent" here in Portland, Oregon. Steve, the owner, has given me a ball park figure of $1800 for a mandrel bent stainless steel exhaust complete from the exhaust manifolds back. (Including two cats.) I'll have a firm price after he gets the truck on a lift and we agree on exactly what the exhaust will look like. I would love to hear any advice on exhaust you guys have!

Big question mark here: How low will the stock oil pan sit? It looks to me like it will be the lowest thing by an inch or so. Anyone who's done this, PLEASE help me out here! I'm thinking I need a new pan, but all of the options I've seen are not compatible with DOD. (Yes I am running the DOD and VVT...) Where does the stock truck pan sit on these trucks? Any pictures? This truck will be driven off road occasionally, so ground clearance is an issue.

Thanks for any help in advance! I'll start getting up pictures in the next couple of weeks.

On my 2wd truck it sits about an inch and a half below front crossmember.

Thanks for the reply! Not good news though... Hopefully somebody with a 4x4 will reply. I've searched all over and can't find this bit of information. I'm sure it's on here somewhere, I just couldn't find it.

I wonder how much it would cost to slice off a bit of my pan? I hate to do that till I know I really need to...

$1800 is crazy expensive for your exhaust! I have a guy in Grants Pass, OR quote me $350 for 3" duals, balance pipe, magnaflo mufflers and the tail pipes tucked even with the corners of the bed. Granted that is just steel and without cats but high flow cats are another $200.

As far as your oil pan goes, you can section an inch out of it as I did on my 1990 p/u. You will lose one quart if oil capacity. I carefully cut the bottom off with a sawzall.retaining the drain plug,then measured up 1 inch and cut that section out and then found a guy to weld it back together.Then modify the oil pickup tube.Your oil pan not hang below the crossmember. Hope this helped.

Honestly I'm not sure how different the L94 is from the LQ9, but that's what I just put in my truck with no issues as far as the oil pan goes. Not sure if it makes a difference but I'm lifted 6" on 35" tires. I can get pics to you and possibly some measurements this weekend when I'm home, if that helps at all. All I know is that I have so much room everywhere it's like the truck was made for a bigger engine.

My exhaust cost me (not including the headers) $325.00 for parts and labor. I bought and supplied the starter pipes with 02 bungs for my JBA headers ($50 something), they recycled my Y pipe and muffler, we shit-canned the old pancake cat and replaced it with a new high flow cat ($220), and added a couple upstream, universal 02 sensors for a 2008 Tahoe. For $1,800, you should at least be getting the 24 karat gold plated edition of your exhaust system.

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Originally Posted by exboatracer

As far as your oil pan goes, you can section an inch out of it as I did on my 1990 p/u. You will lose one quart if oil capacity. I carefully cut the bottom off with a sawzall.retaining the drain plug,then measured up 1 inch and cut that section out and then found a guy to weld it back together.Then modify the oil pickup tube.Your oil pan not hang below the crossmember. Hope this helped.

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Thanks! I was thinking of doing just that; good to hear it can work. I was also thinking of getting a CTS-V pan and welding up a bung that I could drill and tap for the regulator valve. BTW, is yours a 4x4 or 2WD?

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Originally Posted by Blasphemy

Honestly I'm not sure how different the L94 is from the LQ9, but that's what I just put in my truck with no issues as far as the oil pan goes. Not sure if it makes a difference but I'm lifted 6" on 35" tires. I can get pics to you and possibly some measurements this weekend when I'm home, if that helps at all. All I know is that I have so much room everywhere it's like the truck was made for a bigger engine.

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Thanks! Pictures would be great! Maybe if you could measure your pan too? It's weird, all of the info I've seen both here and over at LS1Tech.com show the truck pan as 8.25" deep. Mine is 7.5" inches deep. Did the pans change somewhere along the way?

Yeah, the exhaust quote is spendy, mandrel bending ain''t cheap in this town. I'm considering buying a Y pipe with cats, those go for about $700 or so. Then just having the Cat back section fabricated. The problem with that is the pipe goes under the tranny pan, so to change the tranny fluid you have to drop the exhaust! I'll have another shop quote me a price without the mandrel bending, but I think I'd lose a lot with crush bends?

Thanks for all the replys and help everybody!

I don't know why it uploads the picture sideways and I don't know how to fix it, but hopefully you get an idea of how much room there is around the oil pan. I never once worried about it hitting anything. My engine came out of a stock escalade and it fits in my lifted truck with plenty of room to spare

Thanks for the pics! That's a different pan than mine for sure... Any chance you could measure from the block to the lowest ponit on the pan? I'd really appreciate it if you could! Thanks again!

I forgot to measure my pan (and I live 2.5 hours from where my truck is parked) but I found this, so maybe it will help you. http://www.improvedracing.com/tech/L...dimensions.php

Thanks for the link! It's still confusing though, it matches the other information I've found. It shows the truck pan as 8.34" tall, but mine is 7.5". Also, the pic of your pan doesn't match the truck pan; yours looks like the CTS-V/LS2/LS6 pan. Which would mean yours is only 6.7" deep if it is. Without the lift kit, that bracket to the right of your pan is the low point, if yours is a CTS-V pan that means my pan will be about an inch lower making it the low point. :( BTW, what transmission is that in the pic?

Yeah as far as I know my engine is out of a 2005 Escalade which would make it the LQ9, unless somebody changed the pan to an LS oil pan at some point, but I doubt it. I wish I had the LS2 or LS6 but that would've cost me at least double what I paid! The trans I have is the 4L60E that was already in my '98 truck. But I'll be building a badass 4L80E for it when I get back from Korea this time next year.

Thanks for all the info; I really appreciate it. I wonder if your year Caddy used the CTS-V oil pan? The pictures sure look like that pan... Anyway, it would be great if you could measure that when you get the chance. That measurement along with your pics would tell me exactly where my pan would end up.

BTW, are you in the service there in Korea? I spent seven years in the USAF, but all stateside.

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Originally Posted by Nak

Thanks for all the info; I really appreciate it. I wonder if your year Caddy used the CTS-V oil pan? The pictures sure look like that pan... Anyway, it would be great if you could measure that when you get the chance. That measurement along with your pics would tell me exactly where my pan would end up.

BTW, are you in the service there in Korea? I spent seven years in the USAF, but all stateside.

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Unfortunately I won't have access to my truck until the middle of March because I'm leaving for a training in Southern California for a month. But if you're still stuck then, I'll measure the pan and send it your way. I'm Army, and we have a 9 month deployment to Korea coming up in June. I wish I was USAF cuz you guys have it made most of the time! Army life sucks big time haha

No worries; thanks for your help! I'm guessing you have the CTS-V pan... I'm just going to get my pan shortened as much as I can.

Hope you have fun in Korea. :)

Woo Hoo! The remodel is done and the 5.7 comes out this weekend! I'll get some pictures on here of the progress. My plan is pull the old running gear, clean the hell out of the engine bay and underside, paint the frame with POR 15, Replace the fuel tank & all lines, run the harness, drop the new engine & 6l80 in, run the trans & oil cooler lines, plumb the cooling, tow it in for a new dual exhaust, tow it home & figure out why it won't start. :) Oh, I have to change the shift linkage to cable with an IdidIt kit and install a Dakota Digital cluster.

Attachment 9602Attachment 9603Attachment 9604Attachment 9605Attachment 9606OK, the engine bay is ready except for the distributer. Tommorow I'll cut off the exhaust and drop the T-case & drive lines. I'm thinking of trying to pull the engine & trans as one unit? I have a cherry picker and an electric hoist in the garage, so I'm hoping I can work the duo up and over the radiator support. Any thoughts on that?

Here's the promised pics:

I have all the running gear out. Woo Hoo! The L94 exhaust manifolds are being dropped off for ceramic coating today, as well as both driveshafts for high speed balances & new u-joints and front slip joint repair. The front driveshaft slip joint is frozen solid. I spent hours trying to get it out, then it dawned on me: Just pull the transfer case! Doh!

I ordered a new windshield washer tank & all hardware for a '98 Yukon; it's still available new from GM! The later trucks have it under the battery on the driver's side. My truck has it where my ECM is going to go... I also have the GM parts to move the battery over to the driver's side.

Next step is to drop the fuel tank, pressure wash the hell out of the underside, and POR15 coat the frame and anything else rusty under there. Doesn't look like it's too bad at all, just surface rust on the frame & the body looks clean.

BTW, in the pic of the L94 & 6L80 the wood blocks are just a safety precaution. It all balances fine on that engine stand. Very nice piece!

Now that the 700R4 is out I was able to take some good measurements. Both the 700R4 and the 6L80 are 26 7/8" long from forward mounting surface to the rear mounting surface of the 4WD adapter. As far as the mounting holes for the transmission mount, the distance from the center of those holes to the rear surface of the 4WD adapter is 2.5" on the 700R4 and 1.5" on the 6L80. So, the transmission crossmember will need to be moved 1" rearward. Pretty easy since it just bolts in place with 4 bolts. 4 new holes in the frame and all will be good. The driveshafts and TC shift linkage should line up perfectly. The shift shaft on the 6L80 is about an inch?? further rear than the 700R4. I think I'll be switching to cable linkage--I already have the IdidIt kit-- but I'm going to leave the rod linkage in place to see if it works. Even if it does, I'll probably need to switch to cable to make room for the exhaust.

Edited to add: OK, I measured the shifting shafts. From the front mating surface of the transmission to the center of the shifting shaft: 700R4 9"; 6L80 10.75"

Just been treating rust and cleaning. I'll be coating the underside with POR15 today or tomorrow, then the modifications can begin. First on that front will be stripping the existing harness down to what is necessary: AC, lights, ABS, etc. None of that connects to the ECM on my year, so it'll be a matter of identifying and eliminating all of the wiring for the old ECM. I'll be leaving pigtails on all of the wires going in to the firewall connector for the ECM; that;ll leave a convenient and factory method of running wires in & out of the cab. Also, I'll start on fabricating a mount for my electric fans. They're factory 9 blade fans & shroud out of a 2009 Escalade.

My plans on oil & trans cooling is separate coolers with fluid flow controlled by a thermostat. Any thoughts on that?

Yeah! Good news. I'm using the 1998 fuel tank because the fuel sender unit is compatible with the late model computers. It has a vapor pressure sensor in it, but is the wrong one for the L94. I got the proper one today, GM # 13502903, and it fits right in to the hole for the 1998 sensor. Perfect. I wasn't' sure they if they kept the size the same for the Gen IV stuff. Thank God for GM always keeping damn near everything compatible.

Looks like you're off to a great start. Keep the pics coming and keep up the good work.

Thanks John! More pics soon... I figure no one wants to see the greasy old engine or the greasy engine bay... LOL! Once I get the engine bay clean I'll start posting pics of my progress.

I put the radiator and electric fans in place to see how the fans would fit. Looks pretty good; shouldn't be too hard to install. I'll have to trim the shroud where it hits the steering box. Also, it sit's out about 3/8" on either side. I could trim the top and bottom to get it flush, but on the bottom I'd be trimming away part of the support for the lower mounts. On the plus side it would probably get it off the steering box. I could also just use foam strips to seal the sides. I'll decide on that later. Also, the power steering lines need to be bent out of the way. Attachment 9622Attachment 9623Attachment 9624Attachment 9625Attachment 9626

Here's the new motor mounts. The base of the mounts is convex and flattens out when torqued down. New to me, but apparently as designed.Attachment 9640

Got the L94 in and test fitted today! It's back out now, but I learned a lot doing this. First, my oil pan is fine as is. It's one inch higher than the suspension nearby and the front crossmember. It's three inches higher than the front Diff skid plate. One of these days I'll add a skid plate that covers both the Diff and the oil pan. Also, tons of clearance everywhere, except for one spot I'll talk about in my next post. More than enough room to install the exhaust manifolds after engine installation. Also, no need to remove most of the accessories to drop the engine in. The power steering pump is the exception. Pretty hard to get the motor mount through bolt in place with the PS pump in place.Attachment 9643Attachment 9641Attachment 9642Attachment 9644Attachment 9645

Attachment 9646Attachment 9647Attachment 9648There is a boss that is damn close to the motor mount, maybe 1/8" at best. Also, a tab on the oil pan is awfuly close, the tab right by the offending boss. I'm thinking of grinding about 1/4" of the boss and tab off. Is there any reason I shouldn't? There's no way it could ever be used considering where it is...

Got my exhaust manifolds back from being ceramic coated...Attachment 9649

Got the fan mounts done. I'll post pics of the fan shroud later, I had to chop it up a bit to make it fit. Most of that won't show though, should look pretty factory. BTW, the connectors for the motors are GM # 13580874 or ACDelco PT2649. $15 at Amazon.

Here's the Fan pics. This would be a great mod even for a Stock 350. I picked up a low mileage fan setup complete for $120 on eBay.

I trimmed the bottom down about 1/2" so that it was even with the ridge. Trim the top by the same amount the bottom was trimmed. I also had to remove the driver's side bottom mount; it interfered with the frame. You can see I trimmed the middle mount too. I had to notch the top on both sides to clear the top radiator supports. I cut off extensions on both the left and right side which left a hole, as you can see on the passenger side. I'll patch that later. Then I braced the bottom radiator support with 1/8" x 3" aluminum plate. Below that I mounted a 1/8" x 1.25" steel plate angle iron. That was mounted as to leave 3/8" clearance from the bottom radiator support. I stopped short of my winch control box on the passenger side. The extra wide portion of the bottom support circled in red matches up perfectly with the passenger side bottom mount on the fan shroud.

Later, I'll use a piece of sheet metal to complete the top mount. I'll clean up the cuts with some sandpaper; should look pretty factory when it's done, at least from the top. LOL

This works great! There'es a bit of space on the left and right side between the shroud and the radiator--about 3/8"--which I'll fill with heat resistant foam tape. Easy to put bolt up, easy to remove. Just slide the fan shroud down into the gap between the angle iron and the bottom radiator support, install bolts at top. Factory parts and lots of airflow.
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Got the Holley AC bracket on. Very nice; looks factory. There is one issue. If you look at the idler pulley I circled in red, you can see it is not needed. If you use all of the Holley LS brackets, the belt comes up to the top of the AC compressor from the water pump; so it is needed in that case. However, if you're only using the Holley AC bracket and the rest of the brackets are GM, the belt routes from under the upper right idler pulley to the top of the AC. The circled pulley actually hurts you in this case. It put's the belt closer to being up in the way, it reduces contact with the AC pulley and it adds one more pulley that can fail.

I haven't decided for sure yet, but I think I'll cut off the boss that holds the red circled pulley.Attachment 9656Attachment 9657Attachment 9658

Before you remove that pulley, double check the belt routing. Does Holley offer any information on the routing?

Only if you are using all Holley Accessory brackets. The stock belt routing is required with the GM Accessory brackets--with a small modification to include the AC pulley. Holley has no info on routing if using the GM brackets. Not a big deal, there is only one possible way to route the belt. With the stock GM brackets, the belt MUST come from the bottom of the driver's side idler pulley over to the Passenger side Idler pulley and across the AC pulley, like I show in the Pics. There is no other way. With the Holley brackets the belt comes from the bottom of the water pump pulley and up to the passenger side idler pulley. In that instance, the passenger side idler is absolutely required. I'm going to call Holley before I cut the boss off the bracket, but the more I look at it the more I'm convinced it's the way to go. It'll work with that Pulley there, It looks like a better option not to have it though.

Just spent all day working on cleaning up the wiring from the old harness. The wires going to the old PCM will be cut off and labeled leaving a long pigtail for possible future use for whatever wires need to go from engine bay to cabin. Some wires need to stay--AC and the like. Thank god for wiring diagrams; there's been a couple of wires I might have cut that I actually need... There's been a couple of anomalies as well. A couple of different circuits listed as going to the same pin on the PCM. An error I'm sure. Also, the power--pink wire--to the coil shows NO FUSE? That seems unlikely, but the diagram shows the circuit coming from the ignition switch with no fuse protecting it--just the fusible link that protects the ignition switch itself. This might be true, but I'm going to power the switch and start pulling fuses to see if there is in fact a fuse protecting that circuit. I need to know, because I plan on powering the new harness with that circuit.