This 2.5L BC stroker kit for the Mitsubishi Evo X 4B11T engine platform incorporates a 98mm stroke crank and ProH2K rods. Depending on bore size that you decide, the BC kit will take you up to a 2.5L with a sleeved 90mm bore. This BC rotating assembly features custom CP pistons, steel alloy wrist pins, full ring pack and locks.
Vehicle Fitment:
2008-2015 Mitsubishi Lancer Evolution X
(4B11T CZ4A Evo X GSR and MR models)
Purchase Includes:
4340 billet crank – 98mm stroke
H-Beam ProH2K rods (5.659 c-to-c)
Custom pistons (choice of bore/compression).
Wrist Pins, Full Ring Pack, and Locks
| Part Number: | Description: | Crank: | Rod: | Piston: |
| BC0139 | 2.5L 4B11T | BC5139 – 98mm | BC6135 – 5.659″ | BC7139 – Custom |
Notes:
ACL Race bearings available separately.
Feautres:
• BC 4340 steel billet crankshaft (98mm stroke).
• BC Pro Series connecting rods.
• CP or JE aluminum forged pistons (any bore size, any compression ratio).
• 5100 Series carbon steel alloy wrist pins. 9310 Series pin upgrade available.
• Ductile iron plasma top rings, tapered second ring, low tension oil rings.
• Fully system balanced and ready to install. (50% deposit required)
About BC Crankshafts:
BC crankshafts are crafted from top-grade, aerospace 4340 steel billet material. They are precisely CNC machined using advanced 5-axis Mazak Integrex 300-IV machines to tolerances as fine as .0001″. Each crankshaft boasts large radius journals for added rigidity, ideal for high horsepower, high boost, and high RPM applications. Gun-drilled and CNC-ground oil holes provide a smooth surface for enhanced oiling, with tear-dropped oil scoops, cross-drilled for priority main feeding to the rods, and micro-polished to a mirror finish for optimal bearing lubrication. All cranks undergo stress relief, shot peening, magna flux inspection, and nitriding for peak performance. Fully profiled counterweights are designed to reduce windage in the crankcase, minimizing oil resistance and improving RPM potential.
About BC Connecting Rods:
BC connecting rods are CNC machined from aerospace-grade 4340 steel billet and are available in either the European-influenced H beam or the traditional I beam design (depending on the application). Each rod features a deep, double-ribbed cap to maintain true big end housing bore at high RPMs, ensuring uniform bearing crush and optimal oil supply and load capacity. H Beam rods include a deep radial groove pin bushing and oil holes at the 5 and 7 o’clock positions for critical wrist pin lubrication. I Beam rods have an oil hole at the 12 o’clock position to keep the pin end bore true under high boost. Choose between ARP2000 fasteners (rated to 210,000 psi) or the superior ARP Custom Age 625+ fasteners (rated to 280,000 psi).
Piston Options:
Select from top piston brands CP or JE in any desired bore size and compression ratio. Both brands produce custom BC stroker pistons from 2618 T6 high-tensile-strength forged aluminum. These pistons are computer-designed for maximum strength and minimum weight. Each piston is CNC machined for precise accuracy and optimal grain flow during forging. Utilizing 3D modeling software and Finite Element Analysis, these pistons are crafted to be the strongest and lightest for your application. They offer tighter clearances, reduced noise, better ring seal, and increased durability. Standard features include pin fit, carbon steel wrist pins, and either spiral locks or rail supports based on the application. Optional upgrades include 9310 alloy wrist pins for reduced flex, lateral gas ports for improved ring seal, skirt and top coatings, and a lightweight design.
