2008 Tahoe Engine Swap (2008 LMG to 2013 LC9)

[Coolman1987us]

Hello everyone, I have an 08 Tahoe with an LMG 5.3. It's getting tired at 200k and I’m looking at getting an engine swap ready for the day it goes. I also have a 2013 Sierra with an LC9 with around 120k that has a bent frame and some front end damage. After the accident I brought it in the garage and the engine in the Sierra rolled over and sputtered for a few seconds before I shut it down. I didn't want to run it too long without knowing 100% of the damage but in the accident both the engine and trans lost no fluids at all. Before I tare into this project I was wondering if the swap would even be possible. I know there's a few differences like cast vs aluminum block, newer one has VVT and a different MAF.

I have a few other questions. (reminder this is an 2008 LMG to 2013 LC9 swap)

1. Would I use the ECM from the 08 Tahoe or the 13 Sierra?
2. Are the connections the same?
3. Is it plug and play minus the mentioned differences above?
4. Can the ECM from the Sierra be married to the Tahoe BCM?
5. Do I take the entire engine harness from the LC9 or add the missing wiring to the LMG harness?
6. Does anyone know if HP Tuners software can do all the necessary tuning or do I just bring it to a dealer when I'm done and have them do it with a TechII?
7. Any other useful information would be appreciated! Thank you!

 

[swathdiver]

Hello everyone, I have an 08 Tahoe with an LMG 5.3. It's getting tired at 200k and I’m looking at getting an engine swap ready for the day it goes. I also have a 2013 Sierra with an LC9 with around 120k that has a bent frame and some front end damage. After the accident I brought it in the garage and the engine in the Sierra rolled over and sputtered for a few seconds before I shut it down. I didn't want to run it too long without knowing 100% of the damage but in the accident both the engine and trans lost no fluids at all. Before I tare into this project I was wondering if the swap would even be possible. I know there's a few differences like cast vs aluminum block, newer one has VVT and a different MAF.

I have a few other questions. (reminder this is an 2008 LMG to 2013 LC9 swap)

1. Would I use the ECM from the 08 Tahoe or the 13 Sierra?
2. Are the connections the same?
3. Is it plug and play minus the mentioned differences above?
4. Can the ECM from the Sierra be married to the Tahoe BCM?
5. Do I take the entire engine harness from the LC9 or add the missing wiring to the LMG harness?
6. Does anyone know if HP Tuners software can do all the necessary tuning or do I just bring it to a dealer when I'm done and have them do it with a TechII?
7. Any other useful information would be appreciated! Thank you!

Drop the LC9 in and leave the VVT connector disconnected which will park the camshaft and you're good to go.

Pre-emptively replace the exhaust manifold bolts on each side with new gaskets.

The injectors on the newer motor are shorter and flow just a little bit more, the computer should adjust but if it does not, simply swap over the LMGs intake and throttle body and fuel rail with the injectors with new intake gaskets and call it a day. The gaskets are re-usable but do wear out.

 

[Coolman1987us]

I was hoping you would reply, thank you. After lurking various posts on this site you seem to be the guy who knows what going on.

Funny you say manifold bolts, the lmg has both rear bolt heads snapped already. I'm surprised with 200k there's no noticable blow by or carbon build up, looks like they're not even leaking.

As far as the injector issue, can that be corrected with something like HP Tuners instead of swapping the intake?

 

[swathdiver]

I was hoping you would reply, thank you. After lurking various posts on this site you seem to be the guy who knows what going on.

Funny you say manifold bolts, the lmg has both rear bolt heads snapped already. I'm surprised with 200k there's no noticable blow by or carbon build up, looks like they're not even leaking.

As far as the injector issue, can that be corrected with something like HP Tuners instead of swapping the intake?

Well, most of what I learned came from the guys here on the forum. Many have forgotten more than I'll ever know about these vehicles.

Yes, a tune can correct this. Are you going to leave AFM active or do a physical delete or turn it off in the tune?

 

[Coolman1987us]

.

 

[Coolman1987us]

Well, most of what I learned came from the guys here on the forum. Many have forgotten more than I'll ever know about these vehicles.

Yes, a tune can correct this. Are you going to leave AFM active or do a physical delete or turn it off in the tune?

Probably a physical delete since I'll have it out on the stand already.

Another thing I forgot to mention is the 07 lmg has a 4 speed transmission and the 13 lc9 is a 6 speed. Still should be the same bell housing bolt pattern?

 

[swathdiver]

Probably a physical delete since I'll have it out on the stand already.

Another thing I forgot to mention is the 07 lmg has a 4 speed transmission and the 13 lc9 is a 6 speed. Still should be the same bell housing bolt pattern?

The LC9 will bolt right up to the 4-speed.

Now, since you are mentioning a physical delete you have to pick a new camshaft and open up the engine. Now you can swap front covers, replace the timing chain dampner and pick a non AFM camshaft, either stock or performance. The 2007-2009 LMGs and LC9s ran a single pattern camshaft, the same grind as the camshaft used in the 3rd generation L33. The camshaft that almost always comes with the delete kits is smaller than the ones in either of your motors and would make less power.

The 2010+ LMG and LC9 camshafts are dual pattern to take advantage of VVT. Even without it, almost all cams are split duration these days, except for that Truck Torque camshaft.

Of course you could run a BTR Truck Torque or a Vinci RV camshaft or similar so you don't lose any torque down low where we drive these heavy trucks 99% of the time.

 

[Coolman1987us]

I was looking at Texas Speed's delete kits and they have all kinds of options. I was thinking either their "stock" cam, which I assume means same cam as the non DOD engines, and a "stage 1" cam. If I decide to go with Texas Speed I will probably just call them and tell them what I'm trying to do and have them send me what I need. There are some other kits online I'm looking through but I'm leaning toward Texas Speed right now. Should be around $700 for everything, valley cover, lifters, gaskets, etc.

I guess now that I've written all that I'm thinking about doing a mild "stage one" build. I would like to stay under $2k installed though, of course that's with me doing all the labor. Really probably shouldn't go above what the 4L60 can handle.

 

[iamdub]

I was looking at Texas Speed's delete kits and they have all kinds of options. I was thinking either their "stock" cam, which I assume means same cam as the non DOD engines, and a "stage 1" cam. If I decide to go with Texas Speed I will probably just call them and tell them what I'm trying to do and have them send me what I need. There are some other kits online I'm looking through but I'm leaning toward Texas Speed right now. Should be around $700 for everything, valley cover, lifters, gaskets, etc.

I guess now that I've written all that I'm thinking about doing a mild "stage one" build. I would like to stay under $2k installed though, of course that's with me doing all the labor. Really probably shouldn't go above what the 4L60 can handle.

Their "stock" delete cams are factory cams for non-AFM engines. As @swathdiver mentioned, they're close and run fine on your stock tune other than having AFM turned off. But, they're smaller, meaning a small power loss. The LMG's stock cam, other than the AFM lobes, has the same specs as the famed L33 cam form the Gen3 engines. If you got one of these, you could turn off AFM in the tune and make no other changes and your tune would be optimized for this cam, at least, as optimal as GM made it. The point is that it'd be the cheapest route while not costing any power since you wouldn't need a custom tune. You can have AFM shut off in the tune for as little as ~$60. If you can budget a custom tune and want more power, then look at cams. How wild you go with the cam will determine the type and level of supporting mods.

I was all geared up to do a stock AFM delete in mine. I had an L33 cam and AFM had been tuned out long ago. All I had to do was swap in that cam and the stock non-AFM parts, drop it back in and hit the highway. I had my engine apart and a friend offered me deal on a TSP Stage2. Now, in the middle of the game, extra mods, time, parts and a custom tune became part of the equation. I have no regrets. My point is to determine a plan of action and STICK TO IT. It's a slippery slope and there are plenty of "while I'm here I may as well ______" mods.

 

[Coolman1987us]

Ya the rabbit hole gets deep quick. I pretty much just drive 60 miles a day to work and back and occasionally in the summer I may pull a 20 foot car trailer but that would be rare. I don't really want to dig into the 4l60e yet so I'm only planning on increasing the power to a point say maybe 100 horse torques lower than what it can handle. An I have the 6l80 or whatever is bolted onto the 2013 LC9 so that's also an option to rebuild and swap at a later date. The body is in such good shape I could get another 200k out of it if the engine holds up.

 

[Foggy]

You will def need a good tune if you swap to stage 1 or 'Whatever" stage they want to
call it.. You WILL lose torque and hp down low to swap for more midrange and upper
rpm hp & tq.
Doing the 6L80e trans down the road "may" require a different ECM and of course a new
tune to go with it.. And I don't think it's a direct swap...
IF you're planning on 6L80e swap.... Do it ONCE now and spend the $$$ now and
do it right.

 

[swathdiver]

You will def need a good tune if you swap to stage 1 or 'Whatever" stage they want to
call it.. You WILL lose torque and hp down low to swap for more midrange and upper
rpm hp & tq.
Doing the 6L80e trans down the road "may" require a different ECM and of course a new
tune to go with it.. And I don't think it's a direct swap...
IF you're planning on 6L80e swap.... Do it ONCE now and spend the $$$ now and
do it right.

6L80 swap is a big deal, different cluster, shifter, crossmember, driveshaft, etc. and lots of programming.

 

[Coolman1987us]

6L80 swap is a big deal, different cluster, shifter, crossmember, driveshaft, etc. and lots of programming.

well that settles it, the 6L80 and whatever transfer case is bolted behind it is for sale. 120 something thousand miles

 

[swathdiver]

well that settles it, the 6L80 and whatever transfer case is bolted behind it is for sale. 120 something thousand miles

The transmission and transfer case will bring decent money and help to offset the cost of the swap.

 

[Coolman1987us]

Any idea what transfer case it would be? and what the pair are worth?

 

[Dustin Jackson]

In my book a 120k engine could be just as bad as a 200k engine so I wouldn't go through all the work of swapping in an old motor.

I would probably take both of them apart and see which one is in better condition. Whichever is better condition I would put on a shelf, whichever is in the worst condition I would do a proper rebuild on and that is the one I would install in my Tahoe and then you have a spare 5.3 that you could rebuild as 5.7 or something fun.

 

[Coolman1987us]

In my book a 120k engine could be just as bad as a 200k engine so I wouldn't go through all the work of swapping in an old motor.

I would probably take both of them apart and see which one is in better condition. Whichever is better condition I would put on a shelf, whichever is in the worst condition I would do a proper rebuild on and that is the one I would install in my Tahoe and then you have a spare 5.3 that you could rebuild as 5.7 or something fun.

Not trying to be rude but you probably need a new book. These gen 4 5.3's run 300k plus if you maintain them. I've owned four 5.3's, two gen 3's and two gen 4's, all pushing or over 200k.

 

[Dustin Jackson]

@Coolman1987us I totally agree with you, that is why I am wondering why you are trying to mend a motor with only 200k on it

My point being replacing a 200k motor for one with 120k seems like a lot of work for not much benefit

 

[Coolman1987us]

Long story short the sierra was wrecked and I bought the Tahoe with 198k. Power train in sierra is solid and the Tahoe is starting a very faint tick. The oil sample I sent out to the lab came back with high levels of lead. I'm just getting ahead of the problem because I have the hardware sitting here. Im hoping it'll go to 300k before I need to swap but when it goes I'll have the engine from the sierra ready to drop in, weekend job. Back to work on Monday. At least that's my plan....

 

[iamdub]

well that settles it, the 6L80 and whatever transfer case is bolted behind it is for sale. 120 something thousand miles

I had a böner for a 6L80E swap and researched the hell out of it. A friend swapped a 6L into his '07 Silverado, so I was able to reference him. It would "work", but he didn't know what gear he was in (truck had original cluster) and couldn't use tap up/tap down to manually select gears. I forget exactly what for, but he used a Raspberry Pi module with some custom programming to make something small, but necessary work. The controls go through the BCM, so you'd need to have a way to program that as well as the PCM. By comparison, the wiring is the easy part. Ultimately, I found that it'd be much easier (and WAY cooler) to swap in a manual trans, including sourcing manual trans truck parts from Brazilian models. (Models of trucks built for the Brazilian market. Not Brazilian hotties that sell obscure truck parts.)

If you wanna compare schematics, you probably could swap the powertrain harness and cluster over from the Sierra and have the 6L. Could have VVT as well. You'd still have a lot of labor and would still need to find a way to program the BCM. Speaking of VVT, you could trim that circuit from the Sierra and add it to your '08's harness. Have that turned on in the tune and enjoy a broader powerband.

Long story short the sierra was wrecked and I bought the Tahoe with 198k. Power train in sierra is solid and the Tahoe is starting a very faint tick. The oil sample I sent out to the lab came back with high levels of lead. I'm just getting ahead of the problem because I have the hardware sitting here. Im hoping it'll go to 300k before I need to swap but when it goes I'll have the engine from the sierra ready to drop in, weekend job. Back to work on Monday. At least that's my plan....

Oof. Sorry to hear of the lead. We have so many similarities here. These things are solid, indeed. I did the refresh and hot-rodding to my LMG right at 200K. Literally hit 200K at the dragstrip while getting stock baselines, went to dinner, then home and tore into it the next day at around 200,030 miles. I never cracked apart the bottom end- compression and cylinder walls were great. Cam bearings had the expected wear and I would liked to have changed them. But, at that point, it would've turned into a full rebuild. All I was originally aiming for was to replace all the seals/gaskets and delete AFM. I justified my mods as they could either be sold or used on another build. My hooning for the past 21K miles has been documented here. I've towed long distances (Tampa, FL to Baton Rouge, LA) and taken plenty of two- and 5-hour weekend trips. Just took a road trip to Tampa and surrounding areas back in November- 2,003 total miles including a few 135+ MPH jaunts.

About six weeks before that Tampa trip, a valve spring broke (defective batch). I buffed out the piston face, replaced the bent exhaust valve and slapped it back together with some copper spray on the reused Cometic gasket. All new valve springs, of course. Before I found out how minimal the damage was, I bought a spare engine to have at the ready, just in case mine was trashed. Ended up with a 140K-mile LC9 from a Sierra. It's an '08 or '09, so no VVT. I haven't opened it up yet. Current plans are to build it identically to my LMG so it'll be a plug-and-play long block to minimize downtime for when I pop my LMG. I'll then have the LMG to build up since it's an iron block and I want a turbo.