The BC stroker kit for the Hyundai GK4F Theta 4 cylinder engine platform incorporates a 98mm stroke crank. Depending on bore size that you decide, the BC kit will take you up to a 2.33L with a +1mm overbore to 87mm bore size. The kit utilizes premium steel billet connecting rods in your choice of fastener (ARP2000 or Custom Age 625+ for severe-duty). As usual, each BC kit features custom CP pistons, steel alloy wrist pins, full ring pack and locks. This kit incorporates the Mitsubishi 4B11 connecting rods.
- BC 4340 steel billet crankshaft (98mm stroke).
- BC 4340 Sportsman, Pro Series or I Beam connecting rods (Mitsubishi 4B11T).
- CP or JE aluminum forged pistons (any bore size, any compression ratio).
- 5100 Series carbon steel alloy wrist pins. 9310 Series pin upgrade avail.
- Ductile iron plasma top rings, tapered second ring, low tension oil rings.
- Fully system balanced and ready to install. (50% deposit required)
- Requires Mitsubishi 4B11T rod bearings (ACL #5M1237HX), Hyundai main bearings.
BC crankshafts are made from the finest, aerospace grade 4340 steel billet material. CNC machined on state of the art, 5 axis Mazak Integrex 300-IV CNC machines to exacting tolerances (.0001"). Every crankshaft features large radius journals that add rigidity for high horsepower, high boost, high rpm applications. Gun drilled, CNC ground oil holes feature a smooth surface for extra oiling, tear dropped for added oil scoop, cross drilled for priority main feeding to the rods and micro polished to a mirror finish for optimum bearing lubricity. All cranks are stress relieved, shot peened, magna flux inspected and nitrided (multi step heat treatment) for ultimate performance. Fully profiled counterweights are designed for reduced windage through the crankcase creating less oil resistance for better rpm potential.
BC connecting rods are CNC machined from aerospace grade 4340 steel billet, available in your choice of the European influenced H beam or the traditional I beam design (certain applications). All rods feature a deep, double ribbed cap that keeps the big end housing bore true at extended rpm and insures uniform bearing crush, delivering proper clearances for superior oil supply and maximum load carrying capacity. H Beam rods feature a deep radial groove pin bushing and oil holes at 5 and 7 o'clock (the beam acts as a trough), bringing critical lubrication to the critical wrist pin area. I Beam rods feature a oil hole at the 12 o'clock position that keep the pin end bore true at high boost. Available in your choice of ARP2000 fasteners (rated to 210,000 psi) or the ultimate faster, ARP's Custom Age 625+ (rated to 280,000 psi).
Choose from the top piston brands available... CP or JE... in any desired bore size and compression ratio. Both brands make their custom BC stroker pistons from 2618 T6 high tensile strength forged aluminum forgings. These forgings are computer designed for strength and minimum weight. Each piston dia is CNC machined to assure optimal accuracy and superior grain flow in the forging process. 3D modeling software and rigorous Finite Element Analysis insure that your pistons are manufactured to the strongest and lightest part possible for your application. Your custom pistons feature tighter clearances, less noise, better ring seal and overall better durability. Standard features include pin fit, carbon steel wrist pins and spiral locks or rail supports depending on application. Added features include upgraded 9310 alloy wrist pins for reduced flex, lateral gas ports to assist in ring seal, skirt and top coatings and lightweight design.
The custom pistons included in this kit are called custom because they are truly custom made for you! That means they are not on the shelf ready to ship. Depending on what brand you choose for pistons (CP or JE), and exact specifications you choose, pistons could take any where from 1 week to 6 weeks+ to have made
Stock Specification - GK4F 86mm Bore x 86mm Stroke - 8.661" Block Heigh