McLaren 720S & 765LT Tuning Guide — M840T Engine, ECU Calibration & Full Build Path
The M840T Engine
The McLaren M840T is a 4.0-liter twin-turbocharged V8 that powers the 720S, 720S Spider, 765LT, and 765LT Spider. Developed in partnership with Ricardo, it is one of the most power-dense production V8 engines ever built.
Engine Specifications
| Specification | 720S | 765LT |
|---|---|---|
| Displacement | 3,994 cc | 3,994 cc |
| Configuration | 90° V8, flat-plane crank | 90° V8, flat-plane crank |
| Turbochargers | Twin-scroll | Twin-scroll (higher flow) |
| Peak Power | 710 HP @ 7,250 RPM | 755 HP @ 7,500 RPM |
| Peak Torque | 568 lb-ft @ 5,500 RPM | 590 lb-ft @ 5,500 RPM |
| Redline | 8,500 RPM | 8,500 RPM |
| Compression Ratio | 8.7:1 | 8.7:1 |
| Dry Weight (engine) | 198 kg (436 lbs) | 198 kg (436 lbs) |
| Transmission | 7-speed SSG DCT | 7-speed SSG DCT |
Engineering Highlights
Flat-plane crankshaft. Like Ferrari's F154, the M840T uses a 180° flat-plane crank. This gives the engine a higher-revving character than cross-plane V8s, even-pulse exhaust gas delivery to each turbo, and the characteristic McLaren exhaust note.
Dry sump lubrication. The M840T uses a dry sump oil system, which lowers the engine's center of gravity and ensures oil supply during sustained high-G cornering. This is a motorsport-derived feature rarely seen in road car engines.
Lightweight construction. At 198 kg, the M840T is remarkably light for a twin-turbo V8 producing over 700 HP. For reference, the Mercedes M177 weighs approximately 210 kg and the Ferrari F154 approximately 210 kg. Every component is optimized for mass — aluminum block, lightweight internals, compact turbo packaging.
Top-exit exhausts (765LT). The 765LT uses top-exit exhausts inspired by the McLaren P1. Beyond the visual drama, the shorter exhaust path reduces backpressure and weight.
720S vs 765LT — The Differences
The 765LT is not simply a 720S with more power. The changes include:
- Higher-flow turbochargers with revised compressor and turbine wheels
- Revised exhaust (top-exit on 765LT, conventional on 720S)
- Lighter forged wheels (10 kg lighter per set)
- Carbon fiber body panels (front bumper, fenders, rear bumper, engine cover)
- Revised springs and dampers (10% stiffer front, 17% stiffer rear)
- 35 kg lighter than the 720S overall
- Titanium exhaust components throughout
ECU Tuning the M840T
Access Method
McLaren uses Bosch ECU hardware with manufacturer-level security. The M840T requires bench flashing — OBD access is locked on production vehicles.
Process:
- ECU is removed from the vehicle (located in the engine bay).
- ECU is opened and the processor board is accessed for bench reading.
- Factory calibration is read and archived.
- Modified calibration is developed and verified.
- Modified file is written to the ECU.
- ECU is reinstalled and tested.
For remote customers: Remove the ECU (or have your local shop do it) and ship to us. We calibrate and return within 3–5 business days.
Tuning Results
| Stage | Power | Torque | What It Includes |
|---|---|---|---|
| Stock 720S | 710 HP | 568 lb-ft | Factory calibration |
| Stage 1 (ECU only) | 780–800 HP | 620–640 lb-ft | Optimized boost, timing, fuel maps |
| Stage 2 (ECU + downpipes + exhaust) | 870–900+ HP | 680–720 lb-ft | Full hardware support calibration |
| Stock 765LT | 755 HP | 590 lb-ft | Factory calibration |
| Stage 1 765LT (ECU only) | 820–840 HP | 640–660 lb-ft | Optimized calibration |
What the Calibration Changes
- Boost pressure: Factory boost on the 720S is approximately 1.1–1.2 bar peak. Stage 1 raises this to 1.4–1.6 bar. The turbochargers have significant headroom — they are sized for the engine's airflow capability, not just the factory power target.
- Ignition timing: Optimized across the RPM range, with particular gains in the mid-range where the factory calibration is conservative for emissions compliance.
- Fuel maps: Calibrated for your specified fuel grade (98+ RON / 93 AKI recommended).
- Torque limiters: Factory per-gear torque limits are raised to match the engine's output. This is especially noticeable in first through third gear.
- VMAX: Factory speed limiter removed or raised. The 720S is factory-limited to 341 km/h (212 mph).
- Throttle response: Sharpened. The factory calibration smooths throttle tip-in for comfort; the tuned calibration makes the engine respond more immediately.
Hardware Modifications
Exhaust
The McLaren exhaust system is already lightweight and relatively free-flowing from the factory — especially on the 765LT. Hardware gains are proportionally smaller than on more restrictive platforms.
| Modification | Effect | Estimated Cost |
|---|---|---|
| Sport catalysts (200-cell) | Reduced backpressure, moderate power gain | $3,000–$5,000 |
| Cat-back exhaust (titanium) | Sound enhancement, 10–15 lb weight savings | $5,000–$12,000 |
| Full race system (catless) | Maximum flow, significant sound increase | $4,000–$8,000 |
| Downpipes (sport cats or catless) | Required for Stage 2 calibration | $3,000–$6,000 |
Intake
| Modification | Effect | Estimated Cost |
|---|---|---|
| High-flow air filters | Improved flow, minimal power gain | $300–$500 |
| Carbon fiber intake system | Improved flow, cooler intake temps | $2,000–$4,500 |
Intercooler
| Modification | Effect | Estimated Cost |
|---|---|---|
| Upgraded intercooler | Essential for Stage 2 consistency | $3,000–$6,000 |
Transmission (SSG — Seamless Shift Gearbox)
McLaren's SSG is a 7-speed dual-clutch with electrohydraulic actuation. It pre-selects the next gear for near-instantaneous shifts. The factory shift speed is already among the fastest in any road car.
TCU calibration is available and adjusts: - Shift speed (further reduction from already-fast factory times) - Per-gear torque limits to match engine ECU calibration - Launch control parameters - Shift logic in Sport and Track modes
The McLaren Factor: Carbon Monocage
Every McLaren 720S and 765LT is built around the Monocage II carbon fiber tub. This is not a carbon fiber body panel over a steel structure — it is a structural carbon fiber monocell that forms the core of the chassis.
Why this matters for tuning:
The McLaren's extraordinary power-to-weight ratio is already exceptional. At 1,283 kg (2,829 lbs) dry weight with 710 HP, the 720S has a better power-to-weight ratio than most purpose-built supercars. Adding power through ECU tuning amplifies this advantage without adding weight.
A 780–800 HP 720S at 1,283 kg dry is in hypercar territory — comparable to the McLaren P1 in straight-line performance, at a fraction of the price.
Important Considerations
Warranty
McLaren's warranty and diagnostic system logs calibration states. Any deviation from the factory file is detectable. McLaren dealers will deny powertrain claims on vehicles with modified ECU calibrations.
Recommendation: ECU tune after factory warranty expiration. The standard McLaren warranty is 3 years with no mileage limit, with available extensions.
Cooling
The M840T runs hot from the factory. McLaren's cooling system is adequate for road use and moderate track use at stock power, but becomes marginal at Stage 2 power during sustained track sessions. Consider:
- Upgraded intercooler (essential for Stage 2)
- Auxiliary oil cooler (recommended for regular track use)
- Coolant system inspection at every major service
Turbo Longevity
The factory turbochargers on the 720S are well-engineered and handle Stage 1 boost levels comfortably. At Stage 2 levels (1.6+ bar), the turbos are working harder but remain within their design capability. Stage 3 builds targeting 1,000+ HP may require upgraded turbochargers.
Frequently Asked Questions
Is the 720S the best bang-for-buck supercar to tune? For power-to-weight, yes. The combination of a lightweight carbon tub, a turbocharged flat-plane V8 with significant headroom, and a world-class chassis makes the 720S one of the most effective platforms to modify. +70–90 HP from Stage 1 ECU-only, applied to a sub-1,300 kg car, is transformative.
What is the difference between the 720S and 765LT for tuning? The 765LT's higher-flow turbos and freer exhaust give it a higher ceiling. But the 720S at Stage 1 (780–800 HP) approaches or matches the 765LT stock (755 HP) — at significantly lower purchase price. Both are excellent tuning platforms.
Can the M840T handle 1,000 HP? With upgraded turbochargers, fuel system, and an appropriate calibration — yes. The engine internals (forged crank, forged rods) are strong. The limiting factor at extreme power is the factory turbo size and fuel system capacity.
Does tuning affect the active aerodynamics? No. The active aerodynamic systems (rear wing, air brake) are controlled by the vehicle dynamics module, which is separate from the engine ECU. They continue to function normally with a tuned engine.
Does YPG tune the McLaren Artura? The Artura uses a different engine (M630 3.0L V6 twin-turbo hybrid). Contact us for current availability on this platform.
YPG Motorsport calibrates McLaren engines with the precision they deserve — because a car this well-engineered demands a calibration to match. Contact us →