3.6 LFX swap?

Area to show off your Custom Build threads.
Post Reply

Topic author
Wagonator
Posts: 91
Joined: Sat Nov 16, 2013 2:59 pm

3.6 LFX swap?

Post by Wagonator »

Hey guys,
Since I brought my Wagoneer home over a year ago I have been debating about which engine to drop in since the old girl didn’t come with anything drivetrain wise. I have kicked around the idea for a hemi, coyote, 3.5 ecoboost, 6bt, ecodiesel, GM 4.3, and the LS, of course, but then I came across the LFX. I guess I should have prefaced this by explaining what I want from my rig when she’s built. I’m looking for reliability, just like everyone else, enough power to have some fun if I want (I don’t need 700hp, but 300-400 would be great), but my main focus is fuel economy. I realize we are all on here because we fell in love with these steel bricks so I understand that economy isn’t, or shouldn’t be, a high priority, but I live in northern Nevada and it’s a minimum of 1 hour to get to the next town on an 80MPH highway so 20-24 MPG is my goal. My whole build is a budget build which limits my options even further.

Back to the LFX. This engine has just over 300hp and gets low-mid 20’s for fuel economy in the GMC Canyon. These don’t seem to be very sought after because no one is charging an arm and a leg for one on eBay so the punch to my wallet will be less severe. I have found adapter plates that allow the engine to bolt to a different trans so I’m hoping I can find a way to mate it with a 6L80E (I really just haven’t looked for that specific adapter yet).

It seems this engine has made its way into vehicles as small as Miatas so I’m pretty sure there won’t be any clearance problems. Does anyone have any insight into the LFX? They seem to be reliable, good power, budget friendly, and ticks my MPG box too. Is there any reason not to use one other than the terrible V6 exhaust note?


Sent from my iPhone using Tapatalk
1980 Wagoneer rolling chassis
User avatar

Stuka
Site Admin
Posts: 11789
Joined: Thu May 12, 2011 5:53 pm
Location: CA
Contact:

Re: 3.6 LFX swap?

Post by Stuka »

I think the issue you may run into is a standalone harness for it. Which could be why they are not very sought after. It should make plenty of power for you. And the exhaust actually can sound pretty good if done right.

For trans, I would not put a 6L80E behind it. You are basically just adding a lot of parasitic loss with no real gain. I would keep the 8sp auto that comes behind it.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

Topic author
Wagonator
Posts: 91
Joined: Sat Nov 16, 2013 2:59 pm

Re: 3.6 LFX swap?

Post by Wagonator »

The LFX engines I’m looking at are older, more budget friendly, so they come with a 6 speed. The newer 3.6’s are the LGX engines which are in the newer GMC and Chevys and are mated with the 8L90 or 8L45 (if memory serves). I’d like to have the 8L45 if I can put that behind a 2014-2015 engine.

I shouldn’t need a stand-alone if I pull the engine, trans, ECU/TCU from the same truck, right? I’m not too keen on the compatibility of the electronics of these vehicles.


Sent from my iPhone using Tapatalk
1980 Wagoneer rolling chassis
User avatar

Stuka
Site Admin
Posts: 11789
Joined: Thu May 12, 2011 5:53 pm
Location: CA
Contact:

Re: 3.6 LFX swap?

Post by Stuka »

Wagonator wrote: Tue Apr 20, 2021 2:19 pm The LFX engines I’m looking at are older, more budget friendly, so they come with a 6 speed. The newer 3.6’s are the LGX engines which are in the newer GMC and Chevys and are mated with the 8L90 or 8L45 (if memory serves). I’d like to have the 8L45 if I can put that behind a 2014-2015 engine.

I shouldn’t need a stand-alone if I pull the engine, trans, ECU/TCU from the same truck, right? I’m not too keen on the compatibility of the electronics of these vehicles.


Sent from my iPhone using Tapatalk
That will only work if you are going to be using the gauge cluster, shifter, and do something about the wheel speed sensors. Oh, and the ABS. The standalone controller basically gets around all of that.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
User avatar

ProTouring442
Posts: 673
Joined: Sat Mar 23, 2013 10:28 am
Location: Harriman, Tennessee
Contact:

Re: 3.6 LFX swap?

Post by ProTouring442 »

Contact Speartech and see if they can make you a harness and get the ECM into a stand alone condition.

Topic author
Wagonator
Posts: 91
Joined: Sat Nov 16, 2013 2:59 pm

Re: 3.6 LFX swap?

Post by Wagonator »

So after doing some digging I found https://swapspecialties.com/product/lt- ... e-harness/
They make custom harnesses and custom program PCMs to match your build. That SHOULD take care of the standalone issue.


Sent from my iPhone using Tapatalk
1980 Wagoneer rolling chassis
Post Reply