Remote ECU tune · 6.6L L8T V8 (gas)
A custom Stage 1, 2 or 3 calibration for your Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T, built by hand by a real tuner from your own stock file and datalog, and back with you within three hours of the file arriving. We tune these cars remotely, worldwide: you read and flash with your own HP Tuners interface, and you pay only once the tune is delivered.
Stock vs tuned
From the factory the Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T makes 401 hp and 464 lb-ft (629 Nm). A Stage 1 tune typically adds 20–28 hp and 35–50 lb-ft, for around 421–429 hp in total. With bolt-ons and a Stage 2 calibration that grows to +35–55 hp, and a Stage 3 build — adding a supercharger or other forced induction, with the fuelling to support it — typically lands at 501–551 hp.
| Stage | Added power | Added torque | Total power | Total torque |
|---|---|---|---|---|
| Stock | — | — | 401 hp | 464 lb-ft (629 Nm) |
| Stage 1 | +20–28 hp | +35–50 lb-ft (+47–68 Nm) | 421–429 hp | 499–514 lb-ft (676–697 Nm) |
| Stage 2 | +35–55 hp | +44–70 lb-ft (+60–95 Nm) | 436–456 hp | 508–534 lb-ft (689–724 Nm) |
| Stage 3 | +100–150 hp | +148–236 lb-ft (+200–320 Nm) | 501–551 hp | 611–700 lb-ft (829–949 Nm) |
Typical gains from published dyno results; your car will vary with fuel, mods and conditions.
Tuner's notes
The 2020+ L8T trucks ship with a locked ECM that has to be unlocked or upgraded before tuning. The cast-iron-block, port-injected 401ci engine takes boost well, and supercharger kits list around 600-700 lb-ft at the crank.
Supported versions
HP Tuners lists 4 Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T entries covering 2020–2026, with 6.6-litre engines. Interface: MPVI3/4 for some years.
| Years | Make | Model / engine as HP Tuners lists it | Controller | Credits | Interface |
|---|---|---|---|---|---|
| 2020–2023 | Chevrolet | Silverado 2500/3500 6.6 (L8T) | Engine | 6 | MPVI2/2+/3/4 |
| 2020–2023 | GMC | Sierra 2500HD/3500HD 6.6 (L8T) | Engine | 6 | MPVI2/2+/3/4 |
| 2024–2026 | Chevrolet | Silverado 2500/3500 6.6 (L8T) | Engine | 6 | MPVI3/4 |
| 2024–2026 | GMC | Sierra 2500/3500 6.6 (L8T) | Engine | 6 | MPVI3/4 |
Support data per HP Tuners' supported-vehicle list (June 2026). Check your exact car on HP Tuners' vehicle list before you buy credits.
Stages & prices
One flat price per stage, the same for every car: $250 for Stage 1, $450 for Stage 2 and $650 for Stage 3. Ordering is free and you pay only once the finished tune is delivered. 2 free revisions are included with every order. Gearbox (TCM) shift tuning is included wherever your car's transmission controller can be accessed.
Software only. Every map in the engine ECM is recalibrated for the Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T as it sits today — spark, fuelling, throttle response and limiters — against the datalog you send.
For a Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T with bolt-ons fitted — intake, exhaust, headers or downpipe, and an intercooler where the car has one. The airflow and fuelling are rebuilt around the hardware you actually have.
Stage 3 on the Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T means adding a supercharger or other forced induction, with the fuelling to support it. The fuel, spark and boost maps are written from scratch for your exact combination.
Typical gains from published dyno results; your car will vary with fuel, mods and conditions.
Before you order
How it works
FAQ
Typically 20–28 hp and 35–50 lb-ft (47–68 Nm) over the stock 401 hp, for around 421–429 hp in total. Typical gains from published dyno results; your car will vary with fuel, mods and conditions.
An HP Tuners interface (we recommend the MPVI4), the HP Tuners credits needed to license the engine ECM for writing, and your stock file plus a datalog of a drive. You read and flash the car yourself; we build the calibration.
Your custom tune is delivered within three hours of your stock file arriving. Six tuners work three shifts, so a file that lands in the middle of the night is picked up just as fast.
Stage 1 is $250, Stage 2 is $450 and Stage 3 is $650, flat. Ordering is free and you pay only once the finished tune is delivered. 2 free revisions are included with every order.
Stage 3 on the Chevrolet Silverado / Sierra 2500HD/3500HD 6.6 gas L8T means adding a supercharger or other forced induction, with the fuelling to support it. The maps are written from scratch for your build, and typical results are 100–150 hp over stock. Typical gains from published dyno results; your car will vary with fuel, mods and conditions.
