Base Map After Turbo Upgrade

Hi HP Academy team,

I’m preparing to install a larger turbo on my car and I want to make sure I understand the correct methodology for adjusting the VE table and related maps on a torque-based ECU (SIM2K platform), rather than just guessing numbers and chasing lambda in logs.

Right now, the car is on the stock turbo with a solid Stage 2 setup that has been very stable for about two months (no knock, no issues). I’m reflashing with WinOLS and have DAMOS definitions, including the torque management system and main load/torque maps.

Current situation (stock turbo, Stage 2)

Boost: 24–25 psi (≈ 1.6–1.65 bar)

OEM ECU: SIM2K-250

Model type: Torque-based with VE / torque management system

Target lambda under boost: 0.83

Actual lambda under boost: 0.83 (matches target)

Ignition timing at WOT: ~24° with WMI (was ~21° before meth)

AFR (gasoline equivalent): ~12.2:1

Fuel: 95 RON (Middle East; roughly equivalent to ~93 AKI in the US)

No knock or drivability problems on the current tune

So, on the current turbo, the VE / fueling side is well controlled and lambda tracking is good. The car behaves exactly as expected under the present airflow.

What I am planning

I will be installing a larger turbo.

What I do not know in advance:

Final boost level (it will likely be higher than the current 24–25 psi, but I don’t have an exact target yet)

How the VE table should change with the new compressor (especially in the higher load / higher rpm regions)

How much the turbo speed vs. RPM / load behavior will change, and how that should reflect in the calibration (if there are specific “turbo speed” or related maps, or if this is really just about torque/boost/airload modeling)

Because of that, I want to approach the new setup step by step and avoid doing anything that will make the engine excessively rich/lean or fight the torque model / limiters.

What I’d like guidance on

Where to start with VE changes after a turbo upgrade

On a torque-based SIM2K-250 ECU with a VE/torque model:

Do you usually start by modifying only the high-load, mid-to-high RPM cells where the new turbo will move more air?

Or do you apply some sort of global scaling as a starting point, then refine based on logs?

How “aggressive” should the first VE change be if I want to stay safe but not run crazy rich?

Determining “correct enough” VE values without going way too rich or lean

Given that I can log target vs actual lambda (currently matching at 0.83):

Is the recommended approach to treat VE tuning mainly as lambda error correction (i.e., adjust VE in the cells where actual lambda deviates from target)?

Should I also be looking at MAP, load, HPFP pressure, injector pulse width, torque request vs delivered torque, WGDC and boost error when deciding how much to adjust VE?

Are there “safe starting rules” like “keep initial VE changes within ±X% and verify lambda under short pulls” that you recommend?

Do professionals rely more on calculations or on iterative logging and experience?

For a larger turbo on a known engine:

Do you calculate a new VE surface using air mass models, compressor map data, and injector characterization, then refine with logs?

Or is the practical way mostly iterative: do a pull, compare lambda error, adjust VE in that region, repeat?

If there is a robust way to estimate VE from turbo/compressor data as a starting point, I’d like to understand that workflow.

Which other maps besides VE typically need changes after a bigger turbo on a torque-based ECU?

Specifically on something like SIM2K-250 with a torque management system:

Which torque model / load / aircharge tables are usually adjusted alongside VE?

How do you keep the torque request, torque limits, and boost control coherent when the engine is capable of more airflow and torque?

I’ve heard people say they “change turbo speed vs RPM” maps, but I’m not sure if they literally mean a turbo-speed table, or if they are actually editing boost targets, WGDC, load limits, or torque limits. Any clarification on what should be touched and in what order would be very helpful.

Step-by-step workflow

What I’m looking for is something like a high-level sequence for a torque-based, VE-driven ECU after installing the bigger turbo:

Step 1: Establish conservative boost target and verify fuel system capacity.

Step 2: Do short pulls, compare lambda target vs actual, correct VE in the specific load/RPM areas.

Step 3: Once VE is consistent, clean up torque model / load / limits so the ECU’s predicted torque matches reality.

Step 4: Refine boost control / WGDC and then only at the end, optimize ignition timing within knock limits.

If you have a recommended sequence different from this, I’d really like to hear it.

Vehicle and calibration details (for reference)

Car: 2025 Hyundai Elantra N, DCT, 2.0T

ECU: OEM SIM2K-250 (torque-based, VE / torque management system)

Tuning tool: WinOLS with DAMOS maps (including torque model tables)

Current hardware setup:

Intake

3" downpipe

Spark plugs (colder, appropriate for this power level)

HPFP from Sonata (target is 220 bar and it matched)

Snow Performance WMI, 50/50 VP mix

Upgraded intercooler (AIT around 25°C under load)

Upgraded oil cooler (oil temps around 82°C)

Stage 2 custom road tune (no dyno)

Current calibration highlights (stock turbo):

Boost 24–25 psi (~1.6–1.65 bar)

Lambda target 0.83 and actual 0.83 under boost

AFR ≈ 12.2:1 equivalent

Ignition timing ~24° at WOT with meth (previously ~21° before meth)

Fuel: 95 RON (≈93 AKI US)

I’m not looking for someone to send me a finished map; I’m trying to understand the correct, structured process for updating the VE table and related torque/airload maps when moving to a larger turbo on this kind of ECU, so that each change I make is based on sound reasoning rather than random guessing.

Log file is attached.

Any guidance on methodology or workflow would be appreciated.