Anyone have a LS swapped 3+3?

[CalSgt]

From what I’m seeing, it’s insanely expensive to tune and add functions to. Spear tech mods the harness and can tune the ECM/TCM for only $3,950 plus S&H. The L8T/6L90 are $10k engine, trans, harness and ECM/TCM. It’s still not bad considering the drivetrains have under 20 miles and a GM Connect and Cruise L8T/6L90 is $19k. The LT stuff requires a $500-$700 license fee to tune the ECM alone.

But the L96 6.0/6L90E is not only cheaper but WAY easier to tune and modify. Plus it’s proven platform for reliability.

L8T is about $16k installed 401hp 460tq

L96 is about $9k installed 360hp 380tq

I’m trying to figure out if the extra power is needed. I’ve never driven a 6.0 crew cab dually. Stats are similar to the smog 454 in it.

Im still considering buying a vortec 7400/4l80e to swap in.

My goals are adequate power, OEM multi port fuel injection and overdrive.

I mean really dude…. If MPFI and OD is all you’re after just put the L29 in it and call it a day. You could spend the savings on another square.

If you want something rad do the big LT and 6 speed.

 

[Camar068]

What engine/trans/gear/tire are you running?

K10/LM7 5.3/4L60e/np208/3.73/32"

 

[KnockingDiesel]

I mean really dude…. If MPFI and OD is all you’re after just put the L29 in it and call it a day. You could spend the savings on another square.

If you want something rad do the big LT and 6 speed.

L8T and 6l90e are gonna put me over budget to get what I want. If I can do it for $12k-$14k I’d go for it but like I said all in with cruise control and tow/haul is close to $17k

L29 is an excellent option but I’m not thrilled about a 4 speed auto. If I were towing heavy with it I’d go for 7400 or 8100 but I’m not going to pull constantly. I do like the idea of the mpfi 454 practically dropping in.

I like that LS is still the most common swap so I’ll be able to get everything the way I want and be under $10k.

I have the truck, another bed (in great shape),4x4 frame, np205 case and Dana 60 front.

I’d like to finish the truck with $20k, the only thing I would out source is tuning/harness and headliner.I think I can build a nice truck for that.

That’s why I’m back and forth on it wanting to hear real world experiences. I honestly think the 6.0/6L90E is my best option right now but I have a couple months to decide.

After this truck I’m done with square body trucks. I have had every configuration except the cclb drw 4x4. The only other square I’ll have is my 78 rcsb that’s staying original.

 

[Camar068]

The LT stuff requires a $500-$700 license fee to tune the ECM alone.

if anyone is charging you anything for a license that's old, sorry but you need to find another tuner. If they don't have the license key for something that's old, they are ripping you off.

This is my understanding of licenses, once they pay for it.....it's a one time fee. Someone correct me if I'm wrong. I'm not a tuner, but i believe the license "unlocks" it for that specific vendor/person for life since they've purchased the main software.

when I had mine done, I was waiting for the same instance.....we don't have that one, you'll have to pay extra. But they had that license and we move on with no license fee crap.

 

[KnockingDiesel]

I went with 3.73. I regret not going 3.90 or 4.10 in mine. 4th has absolutley no power. I lose speed going up hill. Part of it's because it's not dyno tuned, but I still wish I'd gone 4.10 or 3.90.

You have to change one or the other. Think about it, google it, look around here, before you make up your mind. I wish I'd listened to others here @HotRodPC

K10/LM7 5.3/4L60e/np208/3.73/32"

Thank you for the info.

This is my concern with the 4 speed auto and 1-1 gear, the 6l90 has a 1.15-1. So with 3.73 and 1.15-1 gear you’d have a final gear reduction of 4.30 where the 1-1 and 4.10 would be at 4.10.

I think the last thing to do is regear once I have the drivetrain in I’ll see how I like the set up. If too wound up I’ll go 3.73 if not I’ll swap the front to 4.10.

 

[KnockingDiesel]

if anyone is charging you anything for a license that's old, sorry but you need to find another tuner. If they don't have the license key for something that's old, they are ripping you off.

This is my understanding of licenses, once they pay for it.....it's a one time fee. Someone correct me if I'm wrong. I'm not a tuner, but i believe the license "unlocks" it for that specific vendor/person for life since they've purchased the main software.

when I had mine done, I was waiting for the same instance.....we don't have that one, you'll have to pay extra. But they had that license and we move on with no license fee crap.

From what I understand it’s a fee to unlock the ECM individually on the L8T, it’s per VIN. I was told I could run a E38 ECM but it would complicate the cruise control, if even possible. Like I said I’m trying to learn as much as I can before I make the final decision.

You must be registered for see images attach

I wasn’t aware of this until a few days ago.

Edit:

The E90/E93 ECM and the TCM have to be unlocked since the TCM is internal to the 6l90E. I haven’t gotten all the details yet waiting on email replies. But it seems $700 and up to $1200 just to unlock them.

You must be registered for see images attach

Some can’t even do the E93 ECM just the E90

 

[Camar068]

From what I understand it’s a fee to unlock the ECM individually on the L8T, it’s per VIN.

rgr that, thought you were talking about a 5.3/6.0 ECM

 

[KnockingDiesel]

rgr that, thought you were talking about a 5.3/6.0 ECM

It’s one one of the many reasons I’m pretty set on the l96/6L90E. I am currently searching for np205 to 6l90 options.

 

[Camar068]

It’s one one of the many reasons I’m pretty set on the l96/6L90E. I am currently searching for np205 to 6l90 options.

adapter needed (part # 50-9552b) long input length. Verify length, this is for the circle pattern NP205. The kits they sell are $800. See if you can make this work.

If in doubt, call Advance Adapters and talk to a tech, they'll tell you what will and won't work. Pretty friendly group.

had to edit my spreadsheet as the link was bad. I think they try to hide this one as this is the 2nd time they've changed the link....they want to sell you the kit lol.

NP205 to 6l80e

 

[KnockingDiesel]

adapter needed (part # 50-9552b) long input length. Verify length, this is for the circle pattern NP205. The kits they sell are $800. See if you can make this work.

If in doubt, call Advance Adapters and talk to a tech, they'll tell you what will and won't work. Pretty friendly group.

had to edit my spreadsheet as the link was bad. I think they try to hide this one as this is the 2nd time they've changed the link....they want to sell you the kit lol.

NP205 to 6l80e

Thank you.

 

[KnockingDiesel]

Well I have the engine and trans for the truck, Vortec 8100 and Allison 1000. Engine, trans, harness and etc $1400 on FB Market Place. I get to keep the big block and get an overdrive.

 

[Hunter79764]

Nice! Don't know anything about the Allison swap, but I've done a little looking at an 8.1 swap and it seems very doable. As far as mounts and exhaust, it's "just a big block", ECM and harness is close enough to standard LS stuff that it shouldn't matter, and fuel system is again, same as LS swap so pretty easy to work with. If you want to modify, it gets expensive, but sounds like a good fit for what you are wanting.

For the record, I've got an 8.1 and Allison 1000 in my Kodiak based Motorhome. It's moving 15-20k all the time and is fine with it. I've wished it had more power when fighting wind on uphill runs, but I'm also 11' tall and 8' wide of aerodynamic cinderblock, so I think that has more to do with it. Getting around town and driving in a reasonable manner with a house on wheels, I feel like I never go over half throttle. And I've got a 6.0/4L60 Yukon XL and a 6.2/8L80 Yukon XL with a TSP Stage 2 VVT cam. I wouldn't pick either of those for a truck I was going to tow with.

 

[Old77]

Only issue I would see with the LS 8.1 is that the engine wasn't around long. Does that impact parts availability at all? Otherwise, awesome choice of powertrain combo

 

[AaronW]

About 13 mpg so not bad. Being TBI and having that overdrive makes a world of difference.

Brief hijack, @ Old77: How much of that 13 mpg do you attribute to the 4 speed trans, versus having TBI? Just curious. On my recent rebuild of my 80 3+3 (not a dually) we got rid of the TBI, installed a 4bbl quadrajet, and kept the 3 speed auto trans, since the machinist who rebuilt my engine said everything he could find was that people were only seeing maybe a 1 mpg improvement, after going to a 4 speed trans. Looks like I'm going to get right on 9 mpg, with my rebuild, but I wouldn't be opposed to doing a different transmission down the road, if mpg gain could justify that. Thoughts?

Aaron

 

[Old77]

Brief hijack, @ Old77: How much of that 13 mpg do you attribute to the 4 speed trans, versus having TBI? Just curious. On my recent rebuild of my 80 3+3 (not a dually) we got rid of the TBI, installed a 4bbl quadrajet, and kept the 3 speed auto trans, since the machinist who rebuilt my engine said everything he could find was that people were only seeing maybe a 1 mpg improvement, after going to a 4 speed trans. Looks like I'm going to get right on 9 mpg, with my rebuild, but I wouldn't be opposed to doing a different transmission down the road, if mpg gain could justify that. Thoughts?

Aaron

IMO, assuming carb is tuned properly and the TBI is working properly for this comparison you'll get most of your MPG improvements with the extra gear in the transmission. I personally thing the MPG difference between an properly tuned carb and a properly operating TBI is very minimal.