Street Spec Pro Closed Deck Shortblock

The Street Spec Pro is designed for more serious weekend track users who demand maximum performance and durability, or for applications generating more extreme power outputs than our Standard short block can handle. The Street Spec Pro is now a fully closed deck block design. "Closed Deck" refers to closing of the open spaces of the head gasket sealing face of the block. The process involves milling pockets in the block to accept press fit inserts precision machined from a cast aluminum material to closely match the expansion rate of the base block material. This deck design serves to reinforce the most highly stressed portion of the cylinder bore reducing distortion and the potential for cylinder cracking associated with extreme power outputs. It also helps to reduce head gasket failures by stabilizing the sealing surface under extreme conditions.

The Street Spec Pro rotating assembly starts with a salt bath nitride hardened crankshaft that is precision balanced for smooth running and reduced bearing loads. We fit our Pro Series tri-beam 4340 connecting rod with ARP L19 bolts. The tri-beam design is a hybrid between an H and I beam design . The rod design is FEA optimized for excellent strength and rigidity with minimal weight. The crankshaft spins in coated ACL tri-metal race series main bearings and low-friction Calico coated Clevite rod bearings for maxiumum durability. Pistons are RCM/Omega forged from 2618 alloy. Pistons and rods are weight matched to within 1/3 gram.

Every short block is professionally assembled in our dedicted engine building room by our in-house builder who has over 20 years of motorsport level Subaru engine experience and has built hundreds of Subaru high performance engines. Every short block is blueprinted to carefully designed specifications that balance extended service life with extreme power capabilities. Every dimension is logged and a build spec sheet is provided for reference. The block is assembled with all typical short block hardware, plugs, and oil separator plate.

The block is optionally available machined for RCM 14/12mm or 14/14mm Superstud oversized head studs. Note that the upgrade price includes a complete set of head studs. 14/12mm head studs use a 12mm head side thread which fits the OEM gasket hole size and cylinder head holes but is an extremely tight fit (modification may make assembly easier). 14mm Superstuds use a 9/16in head side thread which requires drilling the cylinder head holes and enlarging the center two head gasket holes (or running a gasket intended for 14mm or 9/16" stud size such as the RCM ones we sell).

Click here for shortblock comparison and specification chart.

Usually ships in 2 to 4 weeks.

Manufacturer: RalliSpec

Applications:

• Subaru WRX STI MY15-21
• Subaru Impreza STI MY01-14
• Subaru Impreza WRX MY06-14
• Subaru Legacy GT MY05-12
• Subaru Outback XT MY05-09
• Subaru Forester XT MY04-13