Swapping an L86(6.2) into a 5.3 (L83)

[Gavin Faulkner]

Hey everyone,

I just completely blew my motor up yesterday in my 2015 Silverado 5.3 w 6L80. I am wondering what it takes to swap the 6.2 into my truck. as far as harnessed and what not. id love any input i can get. 

Thanks 

[Gavin Faulkner]

the image above is the 3 inch hole in the bottom of the block 

[CamGTP]

If you buy a 2014-2015 6.2 engine it's basically plug and play with the harness, nothing is really different. The later years after 2016 I believe run a different high pressure fuel pump so the connector is different.

 

The rest is tuning.

[gat0r]

just in case, for others on this topic....

 

Fuel pump control module harness

2014-16 are 4 pin and the 2017+ are 3 pin

[AztekxBeast]

On 11/2/2023 at 10:19 PM, gat0r said:

just in case, for others on this topic....

 

Fuel pump control module harness

2014-16 are 4 pin and the 2017+ are 3 pin

Do you know if there is a way to swap that part of the harness out or to change from 4 to 3 vice versa? I have a 2014 with 5.3 looking to swap to 6.2 and I have seen more later model 6.2s in DFW.

[AztekxBeast]

From the research I have found I am happy that I can continue to use the 4L80e that I have lol. It was rebuilt in march so I have like 1-2k miles on it. From what I can see my only concern is the fuel pin connectors between newer models if I can't find a decent motor thats in my year range for direct bolt up. I didn't plan on doing a full rebuilt just the cams and heads to get rid of that nasty AFM. I was also given full bolt on exhaust from my cousin so that as well but I do want something reliable that will last me years to come for sure. 

 

Motor mounts for the 6.2 from 5.3 are also direct bolt ons and placement?

[Snowcamo]

Get the motor block blueprinted  to insure everything is true and it will last you a long time.

[mayutt]

I drive a 2014 Sierra 1500 SLT with an L83. It has over 220K and still runs great, but I'm starting to research an engine swap as I intend to re-engine and keep driving it when this one goes.

 

I see the L86 is a direct form/fit/function minus some tuning...my question is regarding the Flex Fuel sensor. Since my truck is factory Flex Fuel, will it be fine to run the L86 on ethanol too (if I install a rebuilt L86 vice L83)?

[M1ck3y]

On 3/25/2025 at 7:17 AM, mayutt said:

I drive a 2014 Sierra 1500 SLT with an L83. It has over 220K and still runs great, but I'm starting to research an engine swap as I intend to re-engine and keep driving it when this one goes.

 

I see the L86 is a direct form/fit/function minus some tuning...my question is regarding the Flex Fuel sensor. Since my truck is factory Flex Fuel, will it be fine to run the L86 on ethanol too (if I install a rebuilt L86 vice L83)?

yes the l86 can run on e85 but it has to be turned on in the tune.