Mitsubishi 4B11T: The Final Evo Engine That Replaced the Legendary 4G63T

When Mitsubishi launched the Lancer Evolution X in 2008, they faced an impossible task: replace the 4G63T, arguably the most successful turbocharged inline-four in rally history. The 4G63T had powered 4 consecutive WRC championships under Tommi Mäkinen and had a tuning ceiling that exceeded 2,000 HP on aftermarket blocks. Its replacement had to be equally capable.

The result was the 4B11T — a 2.0-liter turbocharged inline-four co-developed with Hyundai and Chrysler under the Global Engine Manufacturing Alliance (GEMA). It was aluminum, modern, and made respectable power. It also divided the Evo community like nothing before, with many enthusiasts considering it a step backward from the iron-block 4G63T.

Factory Specifications

Aluminum Block — The Big Controversy

The 4B11T's most controversial feature is its all-aluminum block. The 4G63T, its predecessor, used a cast-iron block for strength and thermal stability — a design that allowed 1,000+ HP builds on the stock block. The 4B11T's aluminum block is lighter (saving ~50 lb in the nose of the Evo X) but has a lower natural tuning ceiling.

In practice:

• 4G63T stock block: 600+ HP achievable with forged internals
• 4B11T stock block: 400-500 HP is the safe limit before cylinder wall flex becomes a concern

Above 600 HP, 4B11T builds require closed-deck conversion, sleeves, or a complete aftermarket block (IAG, Magnus). These are expensive modifications — meaning the 4B11T's HP ceiling is practically much lower than the 4G63T for equivalent build cost.

MIVEC on Both Cams (First for Evo)

One upgrade over the 4G63T is MIVEC (Mitsubishi Innovative Valve timing and lift Electronic Control) on both intake and exhaust camshafts. The 4G63T MIVEC variant in the Evo IX had MIVEC only on the intake cam. The 4B11T extends this to the exhaust cam, giving the ECU more control over valve overlap and combustion efficiency.

This enables the 4B11T to make more mid-range torque than the 4G63T at similar boost levels — especially below 4,000 rpm where the 4G63T felt laggy.

Direct Injection (GDI)

The 4B11T uses direct injection (Gasoline Direct Injection, GDI) — fuel is sprayed directly into the combustion chamber rather than into the intake port. This is a more modern fuel delivery technology that improves efficiency and combustion control.

However, GDI has drawbacks:

1. Carbon buildup on intake valves — without port injection cleaning them, valves accumulate deposits over time
2. Limited ceiling — high-HP builds often require adding port injection for supplemental fuel above 500 HP
3. Tuning complexity — DI requires specialized ECU knowledge

Known Weaknesses

1. Aluminum Block Flex Above 500 HP

See above. The stock block can crack around the main bearing webs at extreme boost + launch control abuse.

2. GDI Carbon Buildup

Intake valve deposits reduce flow and cause cold start misfires above 80,000 miles. Walnut-blast cleaning is the standard fix ($300-800 shop cost).

3. Transmission (SST) Failure

The Evo X's 6-speed dual-clutch Twin-Clutch Sport-Shift Transmission (SST) is a known weak point — clutches wear, sensors fail, and valve body issues are common. Many owners prefer the 5-speed manual option for reliability.

4. Fuel Pump Internal High-Pressure Pump

Above 400 HP, the internal HPFP becomes a restriction. Aftermarket HPFP upgrades (Cosworth, HKS) are common for high-HP builds.

Real Tuning Limits

4B11T vs 4G63T: The Eternal Debate

Evo IX owners will tell you the 4G63T is the better engine. Evo X owners will defend the 4B11T's modern character. The truth is both are right for different reasons:

For a street-tuned daily driver, the 4B11T is more refined and makes more mid-range torque. For a serious build targeting 700+ HP, the 4G63T is significantly cheaper to achieve.

Famous Applications

Mitsubishi Lancer Evolution X (2008-2016) — The final Evo. 291-295 HP, SST dual-clutch or 5-speed manual, AYC + ACD electronic AWD. Sold until 2016 when Mitsubishi killed the Evo lineage.

Mitsubishi Lancer Evolution X MR (2010-2016) — SST-equipped variant with luxury interior.

Mitsubishi Lancer Evolution X Final Edition (2015) — Commemorative final production (1,600 units USDM).

Factory Service Data

• Oil Change: 7,500 mi
• Timing Chain: Chain-driven (no belt replacement interval)
• Spark Plugs: NGK ILFR7H iridium
• Coolant: Mitsubishi MLC Hyper
• GDI Cleaning: Recommended walnut blast every 80k miles

Conclusion

The 4B11T is a modern, refined turbocharged inline-four that made the Evo X a credible performance car. It's not as hardcore as the 4G63T was, and its tuning ceiling is practically lower due to the aluminum block. But it's also more efficient, smoother, and more responsive at part throttle. The 4B11T represents Mitsubishi's attempt to evolve the Evo formula for the 21st century — and while it never won a WRC championship, it was the last factory-built Evo ever. When Mitsubishi killed the Evo in 2016, they killed the 4B11T with it. It deserves more respect than the Evo community typically gives it.