2019 Silverado L84 LT4 swap tune optimization and validation

[rbass]

Hi everyone,
I'm needing assistance with the tune I've built for my L84 with LT4 swap, this is my first go at tuning a Gen V. I've tried following the Tuning School Gen V flowchart and had to make some assumptions/adjustments since it's not 100% for E90 trucks. I'm making good power at WOT and it's a blast to drive but I'm noticing my city fuel economy is terribly low no matter how I drive it in the city. Taking off like a grandma with hardly any boost it still is wanting to only do about 7-9 MPG in city, once cruising it's ok depending on how I push it anywhere from 14-22MPG - which is somewhat lower there too but not terrible. What should I expect for MPG with no/low boost city driving not pushing it over 2000rpm really?

Mods:
LT4 S/C - machined down cavity on snout directly post throttle body and metal epoxied. Poor mans porting on snout to smooth incoming air.
2.8" ADM pulley - was making too much boost (~11psi due to cats?, backed bypass set screw out until I got ~7psi and truck is much better to drive)
Stock L84
Stock L84 fuel system
Tall LT1 to LT4 adapter plates (2-1/2" runner length addition)
+
Short LT1 to LT4 adapter plates (1/2" runner length addition) - needed both adapters to clear water pump neck.

LT4 rear MAP sensor adapted to factory L84 map connector (3pin to 4pin direct cable extension).
Custom short ram intake tube to factory air box/MAF sensor location.

I'm sure I'm missing some smaller supporting things but that's the setup in a nutshell.

Here's the attached tune and would like for someone to look it over and see where I can optimize some low/mid range drivability within this tune and possibly give me some pointers to better create an "economy" tune for times when I don't want to make any TRX/Raptors cry.
Thank you so much in advance,
Robert

[Estep40511]

can you post a good log to look at>?

[rbass]

Thanks for the quick response, it'll be tomorrow before I'll be able to get a good log file.

[rbass]

Here's a log from earlier in the week. Was a long country drive and a WOT pull.wot_longdrive-121023.hpl

[rbass]

Here's a couple of logs from this morning.
Thanks,
Robert

[GHuggins]

It's most likely where you took the big chunk of timing out. Try changing the cam timing going into the higher engine loads and see if that won't let you put some more timing back into it in those areas so in other words retard it in that area to see if you can add some timing back.

[bonecrrusher]

Rbass - you have any build pics?

I've got a 2022 Silverado ZR2 that I'm starting to collect parts for.

I've got the older L87 water pump, the ICT tensioner kit - and starting to swap pulleys around.

I was looking into the LT4 High flow fuel pump - then found your thread using your stock injectors and high pressure fuel pump. Any issues there?

Did you use the SCIAP breakout harness that is available?

I've got the alternator bracket/idler pulley on order from Magnuson (ADM sent me their way).

What did you end up using for a Heat exchanger?

Thanks!

[rbass]

Rbass - you have any build pics? I'll need to compile them and can share them soon. It's been a process

I've got a 2022 Silverado ZR2 that I'm starting to collect parts for.

I've got the older L87 water pump, the ICT tensioner kit - and starting to swap pulleys around. I'm using the water pump in your attached pic, that's the OEM pump on my L84, NOTE: with factory tensioner add-on kit (since our trucks come with stretch fit belts), ICT Billet alternator bracket, and Dayco 89098 upper idler - my belt I went with was a Gates 935K6, don't remember the pn right off. I installed an upper water neck from a 99-06 Truck pump, routes the upper rad hose well below the S/C snout and LT4 throttle body now. This has been one of my biggest issues on this swap. Besides needing to cut out the wiper cowl bc I went with double head to blower spacers for that water neck clearance. Plus raising the blower higher seems the extra air space between it and the valley cover helps dissipate heat well.

I was looking into the LT4 High flow fuel pump - then found your thread using your stock injectors and high pressure fuel pump. Any issues there? AFAIK, I'm not running out of fuel at the moment. As long as you're not running higher than 6-7psi (2.8" ADM pulley) boost you shouldn't run out of fuel and be in the 550-600hp range. With that pulley, factory cats - my map sensor was reading ~25kPa and truck was kinda boggy, so I backed the bypass set screw in toward the bypass valve until it read right at ~150kPa and seems much happier.

Did you use the SCIAP breakout harness that is available? I actually made a breakout jumper (not paying $300 for something I can crimp together myself, will have to find the parts list - those came from Racetronix if I recall, was a few months back - maybe ran around $30-50 for all the parts/shipping/whatnot. Issue on our L84/L87 platforms is AFAIK, we don't have an IAT wire we can disconnect from the MAF and jumper it to the MAP pin 2 position. Someone correct me if I'm wrong, but I think it's part of the MAF or our ECM uses the ambient temp reading.

I've got the alternator bracket/idler pulley on order from Magnuson (ADM sent me their way).

What did you end up using for a Heat exchanger? Factory LT4, bought from some Chevy dealership online was around $300. I removed the Active air grille, disabled the DTC for it, and installed the ADM mount kit for the 14-18 Trucks with some slight modifications and standoffs for the heat exchanger to mount correctly x/y/z in relation to the position of the front of the truck. Coolant reservoir, I bought a universal black one on Amazon and it's installed in the fender opening on passenger side slightly forward/to right of the battery/fuse box and few inches from headlight bulkhead. I also used the AAG (air grille) 12v switched wire (color is purple and something, not at the truck at the moment) to control the pump relay.

I've been procrastinating to write up the full build/aggregate pics due to laziness and holidays/work. I will post them here and likely create a new forum thread for the overall project in the upcoming weeks. Please reach out if you have any questions, I likely can point you in the right direction or we can figure it out together.

Thanks!

[rbass]

One more quick thing I just remembered as looking at my attached pics, do NOT attach your catch can or anything to the big vacuum nipple directly behind the throttle body from the LT4 SC, it will create a massive suction on the crankcase and set you some P0171/174 codes and you'll hear a hell of a whistle coming from your rear main seal, ask me how I know . Just cap that baby off. This was an old, pre-lessons learned pic rushing to drive it home from my shop.

[bonecrrusher]

One more quick thing I just remembered as looking at my attached pics, do NOT attach your catch can or anything to the big vacuum nipple directly behind the throttle body from the LT4 SC, it will create a massive suction on the crankcase and set you some P0171/174 codes and you'll hear a hell of a whistle coming from your rear main seal, ask me how I know . Just cap that baby off. This was an old, pre-lessons learned pic rushing to drive it home from my shop.

Good to know - thanks for the tips.

I'm still a ways off from starting my swap - but have ordered a few more parts.

I'm just glad to see some other folks going down the LT4 path.

This isn't my first swap - I put an LSA on my Chevy SS sedan - and just wrapped up doing an LS9/2650 swap on my Corvette.

For this project I'm kind of mixing OEM, and aftermarket - I picked up the coolant reservoir, hoses, and water pump brackets from the dealership off of the 3.0 Diesel/Turbo 4 banger trucks.

HX - I scored a cheap Afco HX for a ZL1 Camaro - and will be using 3/4" coolant hoses to integrate all of that.

As for boost levels - The Magnuson 2650 kit doesn't come with injectors, or a high flow pump and uses the stock stuff. So I'll have to see what kind of psi they are making.

Oh and I'll be doing an 8 rib conversion for pretty cheap - and running an ATI balancer.