We use cookies to make your experience better. To comply with the new e-Privacy directive, we need to ask for your consent to set the cookies. Learn more.
Which Rallispec Block do I need? A look at Rallispec's built Subaru EJ Blocks
October 06, 2020
Rallispec has been working on and building high performance Subaru's for the street and for the track longer than almost anyone here in the US. They have taken their experience and put together a line of built Subaru EJ Shortblocks that are ideal for a number of applications. These are available on our site, and we wanted to give you a bit of a guide as to the differences between each option that Rallispec has to offer.
The newest addition to the Rallispec Street Spec series offers the best value for the money of any EJ257 built short block on the market. Featuring the legendary RalliSpec build quality with an affordable price tag. Each short block is assembled in the clean environment of their dedicated engine building room by a highly experienced technician.
The Rallispec Street Spec Light Shortblock offers a quiet and durable engine option for street and occasional track use.
This short block utilizes all new components and is sold outright with no core exchange required. Rallispec starts with an ultrasonically cleaned block case from Subaru. The rotating assembly starts with a salt bath nitride hardened crankshaft running in King XPG race-series bearings. The connecting rods are precisely machined for RalliSpec using South American 4340 forgings and an extremely high strength H-beam design. FEA-evaluated design features around the large and small ends ensure high rigidity with the lowest weight. Rod bolts are ARP 2000. A rod of this quality is not normally found in a short block of this price range. Pistons are Manley forged using 2618 alloy and size graded to the block. Rallispec goes an addiitonal step and size match the pistons to the bores for the most optimal piston-to-wall clearances during assembly as well, and they also position the components to achieve the most optimal balancing. The fully assembled short block includes all block hardware including pin access plugs, covers, and rear main seal.
Unlike Rallispec's other short blocks, measurements are not logged so there is not a build specification sheet for the Rallispec Street Spec Light Shortblock.
This short block does come with a Rallispec warranty against defects during the initial startup period.
Key Specs:
Suggested Max Power: 550 hp
Suggested Max RPM: 7500 rpm
Block Type: Semi-Closed Deck
Block Hardware: Standard
Crank Type: OEM Forged
Piston Type: Manley Graded
Piston Alloy: Forged 2618 Aluminum
Rod Type: Rallispec H-STD rods
Rod Bolts: ARP 2000
Bearings: King XPG
Bore Size: 99.5mm
Compression with STI type B/V/W heads: 8.2
Compression with WRX type D heads: 8.6
Clearances: Checked
Static Balance Tolerance: Optomized with parts as supplied by manufacturer
Crank Dynamic Balancing: OEM Tolerance
Typical Build Time: 2-3 Days
Click here for your Rallispec Street Spec Light Shortblock
The Rallispec Street Spec Shortblock is now built using RCM/Omega Low-X (Low Expansion) pistons. Designed for the low noise and long life essential for a daily driven street application while easily handling increased power outputs and weekend track use. Buit to exacting strandards from the highest quality components.
This short block utilizes all new components and is sold outright with no core exchange required. Rallispec starts with an ultrasonically cleaned block case from Subaru. The rotating assembly starts with a salt bath nitride hardened crankshaft running in King XPG race-series bearings. The connecting rods are precisely machined for RalliSpec using South American 4340 forgings and an extremely high strength H-beam design. FEA-evaluated design features around the large and small ends ensure high rigidity with the lowest weight. Pistons are an ultra-lightweight low expansion piston from Omega. Omega manufactures some of the highest quality pistons available anywhere and have worked with numerous wold championship winning race teams. Their "Low-X" piston runs a very tight piston clearance (around .0020") for exceptionally quiet operation and excellent ring seal. These pistons utilize a low friction moly-based skirt coating.
Every short block is professionally assembled in Rallispec's dedicted engine building room by their in-house builder who has over 20 years of motorsport level Subaru engine experience and has built hundreds of Subaru high performance engines. Every Rallispec Street Spec shortblock is blueprinted to carefully designed specifications that balance extended service life with extreme power capabilities. The dimensions of each Rallispec Street Spec block are logged and included on a build spec sheet is provided for reference. The block is assembled with all typical short block hardware, plugs, and oil separator plate.
Key Specs:
Suggested Max Power: 650 hp
Suggested Max RPM: 8000 RPM
Block Type: Semi-Closed Deck
BLock Hardware: Standard
Crank Type: OEM Forged
Piston Type: RCM/Omega Low-X
Piston Alloy: Forged 4032 Aluminum
Rod Type: Rallispec H-STD
Rod Bolts: ARP 2000
Bearings: King XPG
Bore Size: 99.5mm
Compression with STI type B/V/W heads: 8.2
Compression with WRX type D heads: 8.6
Clearances: Blueprinted/Logged
Static Balance Tolerance: 0.5g
Crank Dynamic Balancing: OEM Tolerances
Warranty Length: 3 months
Typical Build Time: 2 - 3 Days
Click Here for your Rallispec Street Spec Block
The Rallispec Street Spec Pro Value is their most affordable closed deck short block option. However, don't let the price fool you as this short block is built to perform. "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 rotating assembly starts with a salt bath nitride hardened crankshaft running in King XPG race-series bearings. The connecting rods are precisely machined for RalliSpec using South American 4340 forgings and an extremely high strength H-beam design. FEA-evaluated design features around the large and small ends ensure high rigidity with the lowest weight. A choice of either Manley Turbo Tuff in standard and high compression options or Cosworth standard compression boxed-strut piston designs are available (Cosworth pistons available while they last). Manley 2618 Turbo Tuff pistons are an excellent option for extreme power drag racing applications while the Cosworth pistons offer lower noise, longer durability, and lighter weight for street performance, road racing, and other applications.
Every short block is professionally assembled in Rallispec's dedicted engine building room by their in-house builder who has over 20 years of motorsport level Subaru engine experience and has built hundreds of Subaru high performance engines. Every Rallispec Street Spec Pro Value shortblock is blueprinted to carefully designed specifications that balance extended service life with extreme power capabilities. The dimensions of each Rallispec Street Spec Pro Value block are logged and included on 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 1/2in or 14mm head studs for maximum head gasket sealing at elevated power outputs. Note that the price includes a complete set of head studs. Oversized head studs require that the heads be machined to accept the large stud size and the head gaskets must either be designed for them or drilled to size (we suggest RCM head gaskets which are already designed to support up to 14mm head stud sizing).
Key Specs:
Suggested Max Power: 800 HP
Suggested Max RPM: 8000 RPM
Block Type: Closed Deck
Block Hardware: Standard
Crank Type: OEM Forged
Piston Type: Manley
Piston Alloy: Forged 2618 Aluminum
Rod Type: Rallispec H-STD
Rod Bolts: ARP 2000
Bearings: King XPG
Bore Size: 99.75mm
Compression with STI type B/V/W heads: 8.2
Compression with WRX type D heads: 8.6
Clearances: Blueprinted/Logged
Static Balance Tolerance: 1.0g
Crank Dynamic Balancing: OEM Tolerance
Warranty Length: 3 Months
Typical Build Time: 2 - 4 weeks
Other Options: Cosworth Pistons will be avaliable while supplies last, and Manley High Compression Pistons are available by request
Click Here for your Rallispec Street Spec Pro Value Closed Deck Shortblock
The Rallispec Street Spec Pro Cosed Deck Shortblock is designed for more serious weekend track users who demand maximum performance and durability, or for applications generating more extreme power outputs than the Standard Rallispec shortblock 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 Rallispec Street Spec Pro rotating assembly starts with a salt bath nitride hardened crankshaft that is precision balanced for smooth running and reduced bearing loads. They then fit the Rallispec Pro Series tri-beam 300M connecting rod with ARP 625+ bolts. The rod design is FEA optimized for excellent strength and rigidity with minimal weight. The crankshaft spins in low friction coated King XPG race series bearings. Roger Clark Motorsport/Omega forged 2618 alloy pistons are used for this block. Pistons and rods are weight matched to within 1/3 gram.
Every short block is professionally assembled in Rallispec's dedicted engine building room by their in-house builder who has over 20 years of motorsport level Subaru engine experience and has built hundreds of Subaru high performance engines. Every Rallispec Street Spec shortblock is blueprinted to carefully designed specifications that balance extended service life with extreme power capabilities. The dimensions of each Rallispec Street Spec block are logged and included on 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 1/2in or 14mm head studs. Note that the price includes a complete set of head studs. Oversized head studs require that the heads be machined to accept the large stud size and the head gaskets must either be designed for them or drilled to size (we suggest RCM head gaskets which are already designed to support up to 14mm head stud sizing).
Key Specs:
Suggested Max Power: 800 HP
Suggested Max RPM: 8000 RPM
Block Type: Closed Deck
Block Hardware: Standard
Crank Type: OEM Forged
Piston Type: RCM/Omega
Piston Alloy: Forged 2618 Aluminum
Rod Type: Rallispec 300m Rods
Rod Bolts: ARP 625+
Bearings: King XPG
Bore Size: 99.75mm
Compression with STI type B/V/W heads: 8.2
Compression with WRX type D heads: 8.6
Clearances: Blueprinted/Logged
Static Balance Tolerance: 0.5g
Crank Dynamic Balancing: Yes
Warranty Length: 3 Months
Typical Build Time: 2 - 4 weeks
Click here for your Rallispec Street Spec Pro Closed Deck Shortblock
The completely redesigned Rallispec Race Spec Value Shortblock now features a closed deck block design to withstand extreme power levels. The top of the cylinders are reinforced with inserts precision machined from cast aluminum to exactly match the expansion coefficient of the base block material. The reinforcement prevents cylinder expansion, distortion and potential failure of the upper cylinder wall during extreme cylinder pressure conditions. The "pro" closed deck version features additional reinforcement of the block bolt access holes utilizing threaded inserts to partially close off the holes after block assembly.
Every short block is professionally assembled in Rallispec's dedicted engine building room by their in-house builder who has over 20 years of motorsport level Subaru engine experience and has built hundreds of Subaru high performance engines. Every Rallispec Street Spec shortblock is blueprinted to carefully designed specifications that balance extended service life with extreme power capabilities. The dimensions of each Rallispec Pro Shortblock are logged and included on a build spec sheet is provided for reference. The block is assembled with all typical short block hardware, plugs, and oil separator plate.
This short block uses Manley 2618 Extreme Duty Turbo Tuff Series pistons. The extreme duty pistons feature a heavy wall pin that reduces flex under extreme power outputs. Rallispec Pro Series connecting rods are used for this build that are made with a 4340 material and ARP2000 rod bolts. The crankshaft spins in King XPG tri-metal bearings for optimum reliability. The block is precisely bored and finish honed with torque plates for straight and accurate cylinder dimensions. The cylinder crosshatch and piston ring end gap specifications ensure fast break-in and minimal blow-by conditions. The block decks are machined to correct any deck height errors and provide a surface finish for optimum head gasket sealing. The block is assembled with all necessary block hardware and oil separator plate.
Several optional upgrades are available to increase head gasket sealing. A 1/2" head stud package increases the head stud/bolt size from 11mm to 1/2" for additional clamping force. A 14mm head stud package further increases that dimension. The block is machined to accept the larger head studs. Additionally, you must send your cylinder heads to us so the bolt holes can be machined oversize as well. Each package includes the appropriate ARP oversized head studs.
Key Specs:
Suggested Max Power: 1000 HP
Suggested Max RPM: 9500 RPM
Block Type: Closed Deck Pro
Block Hardware: Standard
Crank Type: OEM Forged
Piston Type: Manley
Piston Alloy: Forged 2618 Aluminum
Rod Type: Rallispec Pro
Rod Bolts: ARP 2000
Bearings: King XPG
Bore Size: 99.75mm
Compression with STI type B/V/W heads: 8.2 (9.4 optional)
Compression with WRX type D heads: 8.6 (9.9 optional)
Clearances: Blueprint/Logged
Static Balance Tolerance: 0.3g
Crank Dynamic Balancing: Yes
Warranty Length: 3 months
Typical Build Time: 3-4 weeks
Click here for your Rallispec Race Spec Value Shortblock
The Rallispec 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 Rallispec's pro series closed deck inserts (the pro series closed decking uses a thicker insert and threaded blanking plugs for the bolt access holes to maximize deck rigidity). Either a factory salt bath nitiride hardened crankshaft or an optional Manley billet crankshaft (necessary for operation over 7500rpm) are used based on what you select. Connecting rods are Rallispec tri-beam pro series rods in a 300M alloy and fitted with ARP 625+ bolts to support big power levels reliably. For the Race Shortblock, Rallispec uses RCM/Omega 2618 forged piston with DLC coated heavy duty piston pins. The crankshaft spins in low friction coated King XPG bearings.
At a minimum, we suggest an 11mm ARP 625+ head stud and performance head gaskets but either 1/2in or 14mm oversized head studs are also options for maximum head gasket sealing reliability. Note that oversized studs require drilling the cylinder head bolt holes (Rallispec can provide this service for $150) and running a gasket designed to accomodate the larger stud.
Every block is assembled by our highly experience engine technician with 20 years of Subaru motorsport engine experience. Assembly is done in Rallispec's dedicated engine building room. They 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.
Key Specs:
Suggester Max Power: 1000 HP
Suggested Max RPM: 9500 RPM
Block Type: Closed Deck Pro
Block Hardware: Standard
Crank Type: OEM Forged or Optional Billet
Piston Type: RCM/Omega
Piston Alloy: Forged 2618 Aluminum
Rod Type: Rallispec 300M
Rod Bolts: ARP 625+
Bearings: King XPG
Bore Size: 99.75mm
Compression with STI type B/V/W heads: 8.2 (9.4 Optional)
Compression with WRX type D heads: 8.6 (9.9 Optional)
Clearances: Blueprint/Logged
Static Balance Tolerance: 0.3g
Crank Dynamic Balancing: Yes
Warranty Length: 3 months
Typical Build Time: 3 - 4 weeks
