L83 to L86 Swap

cph60fixr · December 19, 2021

Hello all, new to the Forum. Just became a member so I could share how straight forward swapping an 2015 L83 for a 2018 L86 is. It was absolutely plug and play. The only thing I didn't do is change the LPFP in the tank. And unless I have a problem, I prolly wont replace it. The boot connecting the air box to the TB is larger also.

Snowcamo · December 19, 2021

Sub'd for info on this. I plan to do the same. Looking to see how you liked the swap after. There are a few dead end threads here on this.

Thank you for your time.

dieselfan1 · December 19, 2021

I've often thought about this.

If it's this easy why couldn't I get a LT1 vette motor rated at 455 hp and 460 tq @2600rpm and plug and play with the right electonic components?

BTW the L86 makes peak 460 tq way up at 4100 rpm.

I like peak tq at that lower rpm

35 more hp and the tq peak down low would be ideal for me.

https://www.gmperformancemotor.com/parts/19418843.html

truckguy82 · December 19, 2021

2 hours ago, dieselfan1 said:

I've often thought about this.

If it's this easy why couldn't I get a LT1 vette motor rated at 455 hp and 460 tq @2600rpm and plug and play with the right electonic components?

BTW the L86 makes peak 460 tq way up at 4100 rpm.

I like peak tq at that lower rpm

35 more hp and the tq peak down low would be ideal for me.

https://www.gmperformancemotor.com/parts/19418843.html

L86 and lt1 are the same exact motor with different tuning, exhaust, and intake

CamGTP · December 20, 2021

Other than tuning too, the swap is pretty straight forward.

Also the HPFP on the back of the engines can be different as well. I forget hand which way it is but one is a 3 wire and the other is a 4, if they are different they have to be swapped otherwise the harness won't work.

M1ck3y · December 20, 2021

13 hours ago, cph60fixr said:

Hello all, new to the Forum. Just became a member so I could share how straight forward swapping an 2015 L83 for a 2018 L86 is. It was absolutely plug and play. The only thing I didn't do is change the LPFP in the tank. And unless I have a problem, I prolly wont replace it. The boot connecting the air box to the TB is larger also.

Did your 5.3 blow, or was this an out of pocket swap?

M1ck3y · December 20, 2021

10 hours ago, dieselfan1 said:

I've often thought about this.

If it's this easy why couldn't I get a LT1 vette motor rated at 455 hp and 460 tq @2600rpm and plug and play with the right electonic components?

BTW the L86 makes peak 460 tq way up at 4100 rpm.

I like peak tq at that lower rpm

35 more hp and the tq peak down low would be ideal for me.

https://www.gmperformancemotor.com/parts/19418843.html

I believe the LT1 makes peak torque @ 4500. A custom tune and gears could work for you? Otherwise GM's 3.0 diesel or Turbo 4 would be what your looking for. But I think swapping either of those engines or even finding one would be difficult.

*edit*

Here's what you want

https://www.gmperformancemotor.com/parts/19432060.html

Edited December 20, 2021 by M1ck3y

dieselfan1 · December 20, 2021

31 minutes ago, M1ck3y said:

I believe the LT1 makes peak torque @ 4500. A custom tune and gears could work for you? Otherwise GM's 3.0 diesel or Turbo 4 would be what your looking for. But I think swapping either of those engines or even finding one would be difficult.

*edit*

Here's what you want

https://www.gmperformancemotor.com/parts/19432060.html

You're right it is 4600.

I thought I read somewhere it was 2600.

Disregard what I said and I'll get the 632 instead.

Go big or go hide.

M1ck3y · December 20, 2021

14 minutes ago, dieselfan1 said:

You're right it is 4600.

I thought I read somewhere it was 2600.

Disregard what I said and I'll get the 632 instead.

Go big or go hide.

Can't tell from the dyno but I bet at 2000 rpm it makes more torque then the 6.2 at 4100!

cph60fixr · December 20, 2021

Quote

No, it didn't blow. I had a high RPM misfire on cyl 7. Tried all the easy stuff. Plugs/wires/swapped coils/replaced valve springs/replaced injectors. I think maybe the cam or a weak lifter at this point. It only acted up if I put my foot in it. I haven't driven it yet because I damaged the radiator during the swap. Ordered one from Rock Auto as my local Oreilly's said they couldn't get one...weird right? Truck had 205xxx when I pulled engine.

TJay74 · December 20, 2021

While the physical swap is plug and play, you will need to update the tune in the ECM from the 5.3 to the calibration from the 6.2, so tuning will be required for this swap to work.

For the person who said why dont you swap a diesel into the truck, that wont be possible without a major overhaul and a complete new wiring harness and custom modules as the gas ECM is not setup for controlling a diesel.

The L86 physically is the same engine as the LT1. The block, pistons, rods, crank, cam and heads are exactly the same. The LT1 uses a different intake manifold and different exhaust manifolds and as said different tuning. The high plenum of the L86 will allow it to produce a better torque response over the LT1 intake manifold.

If it was me I would swap all of the fuel system as well, the LPFP, the HPFP and the injectors over the L86 stuff and then add in a ethanol sensor and tune the truck for E85 flex fuel as well. I own a factory L86 truck setup on E85 and runs solid for a 4x4 truck.

M1ck3y · December 21, 2021

14 hours ago, cph60fixr said:

No, it didn't blow. I had a high RPM misfire on cyl 7. Tried all the easy stuff. Plugs/wires/swapped coils/replaced valve springs/replaced injectors. I think maybe the cam or a weak lifter at this point. It only acted up if I put my foot in it. I haven't driven it yet because I damaged the radiator during the swap. Ordered one from Rock Auto as my local Oreilly's said they couldn't get one...weird right? Truck had 205xxx when I pulled engine.

Would it not have been cheaper to rebuild it, make it a stroker? Whats an l86 cost?

M1ck3y · December 21, 2021

12 hours ago, TJay74 said:

While the physical swap is plug and play, you will need to update the tune in the ECM from the 5.3 to the calibration from the 6.2, so tuning will be required for this swap to work.

For the person who said why dont you swap a diesel into the truck, that wont be possible without a major overhaul and a complete new wiring harness and custom modules as the gas ECM is not setup for controlling a diesel.

The L86 physically is the same engine as the LT1. The block, pistons, rods, crank, cam and heads are exactly the same. The LT1 uses a different intake manifold and different exhaust manifolds and as said different tuning. The high plenum of the L86 will allow it to produce a better torque response over the LT1 intake manifold.

If it was me I would swap all of the fuel system as well, the LPFP, the HPFP and the injectors over the L86 stuff and then add in a ethanol sensor and tune the truck for E85 flex fuel as well. I own a factory L86 truck setup on E85 and runs solid for a 4x4 truck.

No one said he should swap in a diesel, and he's already done the swap

cph60fixr · December 21, 2021

I found a 19k mile pull out that came with a 8L90e trans for 6K. Came with harness, ecu's everything still on the engine and it looks brand new. I already had a tune on the 5.3 from mailordertuner.com, will have him send me an updated tune for the 6.2 that turns off the DOD feature and whatever other stuff they do. I do plan on fixing then selling the 5.3/8L90e combo. Should be able to recoup most of the 6k invested in the 6.2.

TJay74 · December 22, 2021

On 12/21/2021 at 7:20 AM, cph60fixr said:

I found a 19k mile pull out that came with a 8L90e trans for 6K. Came with harness, ecu's everything still on the engine and it looks brand new. I already had a tune on the 5.3 from mailordertuner.com, will have him send me an updated tune for the 6.2 that turns off the DOD feature and whatever other stuff they do. I do plan on fixing then selling the 5.3/8L90e combo. Should be able to recoup most of the 6k invested in the 6.2.

You are not going to be able to use the ECM or TCM from the 6.2 setup, you will need to plug your ECM/TCM into the harness and then have your tuner update the tune in each module. The 6.2 ECM/TCM is VIN encoded and TIED to the VIN it was assembled for and that was flashed into them.

The only way around this would be to find someone that can reprogram and flash the ECM/TCM with a VIN change, that will just add more costs and complexity to your swap.