The Race Spec series short blocks are designed and built for the demands of motorsport. The foundation of the Race Spec short block is a new EJ257 block case machined and fitted with closed deck inserts to reinforce the cylinders. We fit either a factory salt bath nitiride hardened crankshaft or an optional Manley billet crankshaft (recommended for operation over 7500rpm). Connecting rods are our tri-beam pro series rods in a 300M alloy and fitted with ARP 625+ bolts to support big power levels reliably. We use an RCM/Omega 2618 forged piston with thick-wall heavy duty piston pins. The crankshaft spins in low friction coated ACL tri-metal bearings while connecting rods are fitted with a Calico-coated Clevite bearing for maximum durability at extreme power outputs.
At minimum we suggest an 11mm ARP 625+ head stud and performance head gaskets but we also offer the block machined for 14mm RCM head studs (with a head side diameter of either 12mm or 14mm). Note that 14/12mm oversized studs can be used with factory head gaskets and unmodified head bolt holes but will be a very tight fit. 14/14mm oversized studs require drilling the heads and using gaskets with larger center holes. Modified or oversized dowels are required as well.
Every block is assembled by our highly experienced engine technician with 20 years of Subaru motorsport engine experience. Assembly is done in our dedicated engine building room. We use highly accurate and calibrated equipment such as Mitutoyo digital micrometers, Sunnen 0.0001" reading dial bore gauges and setting fixtures, Ohaus digital scale with 1/100 of a gram accuracy, and Snap-on digital torque wrenches. Every measurement is logged and a detailed build spec sheet is supplied with each engine for your reference.
Click here for shortblock comparison and specification chart.
Usually ships in 3 to 4 weeks.
| Part No. | Description | Displacement | Price Ea. | Add to Cart |
|---|---|---|---|---|
| RSB-RS25 | RalliSpec Race Spec Shortblock 8.2:1 (8.6:1 EJ255 D25 Head) | 2.5L | $6150.00 |  |
| RSB-RS25HC | RalliSpec Race Spec Shortblock 9.4:1 (9.9:1 EJ255 D25 Head) | 2.5L | $6150.00 | |
| Part No. | Description | Price Ea. | Add to Cart |
|---|---|---|---|
| RSB-MANCR | Upgrade to Manley Billet Crankshaft 79mm | $1500.00 | |
| RSB-OP-OILSQ | Machine and Fit Piston Oil Sprayers (Includes Parts) | $495.00 | |
| RSB-OP-HS12 | Upgrade to RCM 14/12mm Head Studs (Includes Head Stud Kit) | $695.00 | |
| RSB-OP-HS14 | Upgrade to RCM 14/14mm Superstud Head Studs (Includes Head Stud Kit) | $795.00 | |
