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Street Spec Standard Shortblock

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. The Street Spec shortblock now features a much higher performance rod manufactured to our specific requirements. Rods are forged from heat treated & stress relieved 4340 chromoly. Pistons are from Cosworth and utilize a slipper skirt design for low frictional losses and an advanced boxed bridge forging for high rigidity and minimal weight. Crankshaft is an OEM forged and induction hardened unit. Bearings are King XP Gold offering extreme load carrying capacity and high temperature resistance with the tightest control of shell thickness in the industry. Assembled using all new components.

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).

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. The 2.0L short blocks are available as either an EJ205 open deck block or EJ207 semi-closed deck block (GRB casting).

Do you use the nitrided factory crankshaft? The current 2.5L 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 Standard short blocks have pistons matched to within 1/4 gram and connecting rods matched to within 1/2 gram end to end. Dynamic balancing of the crankshaft is left at factory tolerance.

Is it possible to have this crank assembly dynamically balanced to motorsport type precision? Yes, we can do this for a $250 additional charge. To achieve the best results we suggest you supply the crank pulley, crank timing sprocket, flywheel, clutch pressure plate, and related hardware so these items can be balanced at the same time.

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 Street Spec Pro are set to 0.0025".

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.