The Gruppe-S 2.5 Stage One Short Block transforms your STI engine to a fully forged short-block. It is designed to reduce the compromise between high horsepower and reliability. Derived from our extensive experience building and tuning both race and street cars our short-block eliminates the failure points of the stock STI engine. We replace the stock hyper-cast pistons with our custom forged units by Wiseco. We selected Wiseco pistons due to their versatility for both street and race applications - namely they eliminate the compromise of a "loose" race piston with a better operating range. The factory connecting rods are replaced with Helix forged H-beam rods featuring the ultra-strong ARP L-19 race series rod bolts. -HThe factory bearings are also replaced with coated race units, which eliminate the spun / seized bearing issue we often see in high power applications. Finally the entire assembly is professionally balanced and assembled.

We recommend this short-block for all Subaru owners making in excess of 460HP. Can the stock motor hold more power? Yes. But based on our experience building and tuning literally hundreds of Subarus, the reliability of the engine becomes questionable at those power levels.

Our short blocks features brand new components with the exception of the block halves. The block-halves are sourced directly from Japan. Our block halves are bored and honed for a larger 0.5mm bore which slightly increases compression. The benefits of using used block halves are that they have already been heat cycled and stress relieved (through use), thus eliminating the common failures with brand new un-stress relieved aluminum blocks. If you elect to trade in or have us rebuild your existing block ($500 credit) we will reuse your block halves and crankshaft. The crankshaft will be refinished and balanced as necessary. All other components are brand new.

FEATURES:

*Gruppe-S / Wiseco Forged Pistons
*Helix Forged Connecting Rods with ARP L19 Rod Bolts
*Coated High Performance Rod & Crankshaft bearings
*Professionally balanced and assembled
*Capable of up to 535HP Operation
*Final Displacement 2.48L
*Compression ~8.5 : 1

Our short blocks features brand new components with the exception of the block halves. The block-halves are sourced directly from Japan. Our block halves are bored and honed for a larger 0.5mm bore which slightly increases compression. The benefits of using used block halves are that they have already been heat cycled and stress relieved (through use), thus eliminating the common failures with brand new un-stress relieved aluminum blocks. If you elect to trade in or have us rebuild your existing block ($500 credit) we will reuse your block halves and crankshaft. The crankshaft will be refinished and balanced as necessary. All other components are brand new.