Understanding the 4B11T Engine

The Mitsubishi 4B11T is a 2.0-liter turbocharged inline-four engine that debuted in the Lancer Evolution X in 2007. Built on an all-aluminum block with an open-deck design and cast-iron cylinder liners, it weighs significantly less than its iron-block predecessors like the 4G63. The engine uses MIVEC variable valve timing on both intake and exhaust cams, a twin-scroll Mitsubishi TD05 turbocharger, and direct-acting bucket tappets that allow for high-rpm durability. Out of the box, the 4B11T produces around 291 hp and 300 Nm (221 lb-ft) in USDM spec, but its factory-forged pistons and robust connecting rods have proven capable of handling 400+ hp on the stock bottom end with proper tuning. The combination of a lightweight rotating assembly, excellent cylinder head flow, and a strong block make the 4B11T a favorite for enthusiasts chasing 400+ hp and 300+ ft-lb torque.

Key Components for High Performance

Breaking the 400 hp mark requires a holistic approach that addresses airflow, fuel delivery, and engine management. Below are the critical components and common upgrade paths for 4B11T builds.

Turbocharger and Exhaust Manifold

Stock TD05 runs out of steam around 350 whp. To exceed 400 hp, popular choices include the BorgWarner EFR 7064 or ETS 5451 turbo kits. For those wanting a bolt-on path, the FP Red or Maptun Stage 3 turbos deliver 400+ hp with proper supporting mods. A divided t4 or twin-scroll manifold paired with a 3.5-inch downpipe reduces backpressure and improves spool.

Fuel System

Stock fuel pump and injectors max out around 350 hp. Upgrading to an ID1050x or FIC 1000cc injectors and a Walbro 450 or AEM 340 pump is mandatory. For ethanol blends, consider a direct-port meth injection kit or larger return-style systems.

ECU Tuning

Factory ECU can be reflashed via standalones like ECUMaster EMU Black, Link G4+, or Motec M1. A proper tune by shops like English Racing or AMS Performance optimizes timing, boost, and fuel maps for e85 or 93 octane.

Induction and Exhaust

Mandrel-bent 3-inch intercooler piping, a large bar-and-plate core, and a K&N Apollo or AMS cold-air intake reduce intake temps. On the exhaust side, a Tomei Expreme or Milltek cat-back system paired with a high-flow cat or test pipe helps flow.

Cooling and Oil

Stock radiator is marginal at 400 hp. Mishimoto X-line or Koyorad aluminum radiators and an oil cooler are recommended for sustained hard driving.

Build 1: The Street Monster – 420 hp / 310 ft-lb

This build prioritizes responsive power for daily driving and highway pulls. The owner selected a BorgWarner EFR 7163 turbo with a .83 A/R turbine housing. Combined with a Full-Race twin-scroll manifold and a 3.5-inch downpipe, the car spools 18 psi by 3500 rpm. Fuel is supplied by FIC 1200cc injectors and a Walbro 450 pump. Tuning was performed on 93 octane by DynoComp, yielding 420 whp and 310 ft-lb on a Dynojet. Supporting mods include Mishimoto intercooler and an HKS SSQV blow-off valve. The engine remains stock internally, with a conservative 22 psi peak boost and timing pulled mid-range to ensure reliability. On the street, the car pulls hard from 3k to 8k rpm and remains docile enough for traffic.

Build 2: The Track Beast – 450 hp / 320 ft-lb

A semi-built short block was used to withstand sustained high loads. Stock block was reinforced with Manley H-beam rods and Wiseco 9.0:1 pistons. The head received Kelford 272 cams and GSC valve springs. Turbo choice is an Precision 5858 Gen2 with an ETS 4-inch intercooler. Fuel is ID1700x injectors and a triple pump setup feeding e85. A Motec M1 ECU allows for advanced traction control and boost-by-gear. On a Mustang dyno, the car put down 450 whp and 320 ft-lb at 26 psi. The oil system was upgraded with a Moroso oil pan and Setrab cooler. At the track, consistent 11-second quarter-miles and reliable 30-minute road course sessions are achieved.

Build 3: The Weekend Warrior – 410 hp / 305 ft-lb

This budget-friendly build keeps the stock turbo but runs a Mamba Evo X 19T wheel and a GrimmSpeed boost controller. Fuel mods: DeatschWerks 320 pump and FIC 850cc injectors. An AMS cold-air intake and 3-inch catless exhaust complete the airflow. Tuning via ECUMaster EMU Black on 91 octane results in a safe 410 whp and 305 ft-lb. The owner emphasized drivability, using stock cams and a conservative 18.5 psi tune. Cooling is addressed with a Koyorad radiator and SPAL fan. The car sees canyon runs on weekends and has run a 12.3 quarter-mile on street tires. The stock bottom end has 30,000 miles on this setup with no issues.

Build 4: The All-Rounder – 400 hp / 300 ft-lb

Designed for versatility, this setup uses a Garrett GTX3576R Gen2 turbo on a Mitsubishi Motorsport manifold. Fuel system is a Radium surge tank with twin Walbro 450s and Injector Dynamics ID1050x injectors. The car runs e85, tuned by Mitsubish Tuning to produce 400 whp and 300 ft-lb. Supporting mods include a HPS silicone charge pipe kit, Haltech S1 Elite ECU, and a full HKS Hi-Power cat-back. The owner reports a snappy throttle response, zero knock on e85, and a flat torque curve from 3800 to 7000 rpm. The car is used for daily commutes, autocross, and occasional time attack events.

Reliability Considerations at 400+ HP

While the 4B11T can handle 400+ hp with stock internals, longevity requires attention to several areas:

  • Oil starvation: Track cars should install a baffled oil pan (e.g., Moroso) and a high-volume oil pump. Street cars with occasional pulls often survive with an upgraded cooler.
  • Cooling: At sustained boost, stock cooling can cause heat soak. A 180°F thermostat, high-flow water pump, and aftermarket radiator are recommended.
  • Knock control: Use high-octane fuel or ethanol to allow aggressive timing without detonation. Quality dyno tuning is non-negotiable.
  • Fueling headroom: Ensure injectors stay under 85% duty cycle. A lean condition at high load can destroy pistons quickly.
  • Rod bolts: Many builders replace rod bolts with ARP studs for extra margin at high rpm.
  • Clutch and driveline: Stock clutch will slip over 350 ft-lb. Upgrade to a South Bend Stage 3 or Exedy Hyper Twin.

Proper maintenance—frequent oil changes (every 3000 miles), spark plugs gapped appropriately for boost, and regular compression tests—will keep a 400+ hp 4B11T reliable for tens of thousands of miles.

Conclusion

The 4B11T engine offers remarkable tuning potential, with dozens of documented builds exceeding 400 hp and 300 ft-lb of torque. Whether you choose a budget-friendly stock-turbo upgrade or a full race setup, the key lies in matching supporting mods to your power goals and using professional tuning. The builds highlighted here prove that with careful component selection and attention to cooling, fuel, and engine management, the 4B11T can deliver thrilling performance while remaining dependable for daily or track use. For more build examples and tuning tips, see the EvoM forums and shops like AMS Performance.