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Race Spec Value Shortblock

The Race Spec series short blocks are designed and built for the demands of motorsport. The Value version is our entry level Race Spec shortblock. It features Omega 2618 forged pistons, our high performance 4340 chromoly rods with ARP L19 bolts, and King XPG bearings. The crankshaft is an OEM forged induction hardened unit. This is not a sleeved block but is fully blueprinted and balanced. Assembled from all new parts.

Click here for shortblock comparison chart.

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Manufacturer: RalliSpec


  • Subaru

What is the recommended break-in process for the engine? This information along with warranty details can be downloaded here: Engine Warranty & Break-in Instructions (PDF).

Why do you use Omega pistons in the Race Spec and Cosworth in the Street Spec series? Omega is a highly regarded piston manufacturer in the UK with experience developing pistons for racing teams running at the highest levels ranging from F1 to WRC to MotoGP. The Omega forged pistons we are using are a lightweight slipper design precision machined from a 2618 heat treated aluminum. This alloy offers maximum strength and superior thermal conductivity (potentially reducing piston crown temperatures). This makes it the optimum choice for racing applications. Cosworth pistons, also a slipper piston but a litter heavier design, are machined from a Cosworth proprietary alloy similar to 4032. This is a low expansion high silicon aluminum with excellent wear resistance and the piston is designed with a pin offset for reduced noise making it ideal for street driven applications. Both Cosworth and Omega offer pistons with a level of quality and engineering far superior to other options of the market. Yes, there is a premium to be paid for this level of quality. However, we feel strongly that achieving maximum performance and maximum durability requires a no compromise approach when it comes to piston selection.

What engine block casting is used to assemble the engine? We have no choice in the selection of the engine blocks. We purchase the current engine block part numbers available from Subaru. Currently the EJ257 blocks coming from Subaru are all "704" castings. The EJ257 block is a semi-closed deck design.

Do you use the nitrided factory crankshaft? The current crankshaft we are using is induction hardened. The nitriding process is no longer being used and those cranks are not available any more. However, the two processes are both used to increase the surface hardness of the crankshaft. We have found no significant advantage of one over the other.

What is the balance process used when building this short block? Street Spec Pro short blocks have pistons matched to within 1/4 gram and connecting rods matched to within 1/2 gram end to end. The crankshaft is dynamically balanced to 0.25 oz in.

Is the block honed with a torque plate? Yes, we always fit a torque plate during the honing process to simulate the distortion created by the cylinder head bolt torque. We suggest you indicate to us what cylinder head hardware, torque values, and head gaskets will be used so we can most accurately replicate the loads. When this information is not supplied to us our standard process is to use ARP standard head studs torqued to 90ft-lbs with an OEM head gasket.

What clearances are used for piston-to-cylinder and for crankshaft bearings? The clearances we use are based on extensive testing and experience. Oil clearances are increased over the factory settings to allow for significantly increased loads and component distortions. The engines require a 5W40 / 10W40 (road) or 10W50 / 15W50 (race) oil viscosity and a minimum of an 11mm oil pump. Piston clearances on the Race Spec value are set to 0.0035".

What is the maximum boost pressure for this short block? We are often asked this question. Boost pressure on its own will not overstress an engine. Peak cylinder pressure after the spark plug fires will be significantly higher than any useable boost pressure. Increased boost pressures generally lead to increased cylinder pressures and heat loads which can overstress an engine. But the exact correlation depends greatly on the tuning, the type of fuel, and other factors. Its impossible to tell you what the maximum boost pressure the engine will handle will be.

What is the maximum rpm of the short block? There are many factors to consider when establishing a maximum rpm for a particular engine. Our shortblock comparison chart offers a suggested maximum rpm provided all other contributing aspects of the engine assembly have been designed to support that rpm. It is also important to understand that it makes no sense to attempt to increase revs if the engine's power is already falling off significantly or is running outside the efficiency range of the turbo. Additionally, there are often limitations in the factory oil and cooling systems that make significant increases in rpm unwise without a proper re-evaluation of those systems.

Can I substitute different pistons or rods? Our engines have been developed using what we believe are the finest components available within the target price range. In particular, when selecting pistons and rings for our Street Spec engines we took into account the desired characteristics of low noise, maximum longevity, and reduced blowby/oil consumption under typical street use drive cycles. Although we are happy to build a short block or long block to your specific requirements if you feel strongly about a certain setup, we treat any deviation from our standard engines as a custom job. We feel that our off-the-shelf engines represent the best possible combination of components and processes.