Our Stage 1 fully built FA20 Turbo shortblock supports up to 500bhp with proper tuning and supporting modifications. Our short blocks are race proven for durability and reliability under the most demanding conditions. Available for turbocharged BRZ or 2015-2021 WRX models. WRX variants may select between Manley and Mahle piston options.
Every build goes through a rigorous ultrasonic cleaning, measuring, and assembly process with each measurement logged for future reference. Components are weight matched and carefully machined and polished as required to achieve the desired tolerance. Bearing clearances are measured with calibrated Mitutoyo micrometers and precision Sunnen dial bore gauges and adjusted to within +/- .00015" by substituting bearing shells. Piston ring gaps are hand filed to within .001"of the target clearance which is based on the intended use and expected power levels.
The components used in this short block are as follows: FA20 Block Case w/ Factory Pinned Mains , Manley or Mahle 2618 Forged Pistons, RalliSpec H-Beam 4340 Forged Rods by Saenz, ARP2000 Rod Bolts, ACL Tri-Metal Main and Rod Bearings, Nitride Hardened Crankshaft, Rear main seal, block plugs & covers included.
One year limited warranty when professionally installed and registered
Click here for shortblock comparison and specification chart.
Click here for warranty and engine break-in information.
What is the warranty for the engine? This information along with break-in process details can be downloaded here: Engine Warranty & Break-in Instructions (PDF). We fully stand behind the quality of our short blocks but there are many factors outside of our control that will contribute to or detract from the reliability and life expectancy of the engine. Poor tuning, improper or lack of maintenance, failure to select the proper supporting components for the power output, or engine cooling issues are often the culprits behind many engine failures. However, we understand the frustration a customer might experience after investing a significant amount into a built engine only to have it fail. Therefore, we will provide a one-time 20% discount on any replacement shortblock when a failure does not meet the requirements of our warranty coverage. Only the original purchaser is eligable to obtain this discount and only within 2 years of original purchase date.
What is the compression ratio? The compression ratio depends on the head gasket thickness and cylinder head combustion chamber volume. Manley pistons provide a 10.0CR when using factory gasket thickness and the correct shortblock has been supplied for the application. Mahle pistons provide a 10.5CR with factory gasket thickness and WRX DIT heads.
What is the balance process used when building this short block? We weight match the pistons assemblies to within 1 gram of each other using a milling machine to precisely remove material from the least critical locations. We also weight match the connecting rods to within 1 gram end to end removing material only from the least critical locations and polishing the weight removal areas so as minimize any stress risers. We retain the crankshaft dynamic balance as supplied from the factory. The option to precision balance the crankshaft is available for an additional cost of $200 by special order. However, often times the majority of the imbalance in a rotating assembly is due to the clutch and flywheel assembly because of the signficant weight and its distance from the rotational centerline. If dynamically balancing the crankshaft, the best option is to ship to us or purchase from us the clutch, flywheel, and crank pulley so that all these components can be precision balanced at the same time.
Is the block honed? The block is not honed unless we find excessive distortion or an inability to achieve our desired piston-to-wall clearance within a tolerance of +/- 0.0002in. The price of this block does not allow for this machine work unless absolutely necessary. Each piston and bore is measured to a precision of 0.0001" using specialized equipment and pistons selectively matched to each bore in order the achieve optimal clearance. Rest assured this short block is far beyond the "drop in piston" short blocks competitors are typically selling.
What clearances are used for piston-to-cylinder and for crankshaft bearings? The clearances we use are based on extensive testing and experience. Rod bearing 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. Piston-to-wall clearances fall within the 0.0025 to .0030in range depending on the pistons.
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 flow rate of the turbo, 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.
