If the Toyota 4AG is a firecracker, the Subaru/Toyota FA20 is a stick of dynamite. Featuring direct injection, high compression, four valves per cylinder, and variable valve timing for both intake and exhaust events, the FA20 showcases today’s latest engine technologies. This compact, all-aluminum, 2.0-liter boxer engine delivers performance through efficiency. At just 7,000 rpm, the FA20 hits the 100 horsepower-per-liter mark. For comparison, the 4AG would require extensive modifications, race gas and over 8,500 rpm to generate 160 horsepower (100 horsepower per liter).

Introduction by Michael Ferrara, Engineering by TOMEI POWERED


FA20 ENGINE SPECS
DISPLACEMENT: 1,998
ENGINE TYPE: Flat 4 / Boxer
COMBUSTION CHAMBER: Pentroof
VALVE TRAIN: DOHC 16 Valve/Chain Driven
VARIABLE VALVE TIMING: Intake and Exhaust
BORE X STROKE: 86mm X 86mm
COMPRESSION RATIO: 12.5:1
FUEL SYSTEM: Direct Injection with Port Injection
MAX HORSEPOWER: 200 hp @7000RPM
MAX TORQUE: 151 lb-ft @ (6400-6600)
INTAKE VALVE TIMING: Open / 44° ~ -24° BTDC
Close / 31° ~ 99° ABDC
EXHAUST VALVE TIMING: Open / 81° ~ -27° BTDC
Close / -9° ~ 45° ABDC
FIRING ORDER: 1-3-2-4
FUEL: Premium Unleaded

FA20 engine

While the “86” moniker of the FR-S/BRZ platform evokes comparisons to the 4AG, the new FA20 engine represents the evolution of another popular engine series: Subaru’s EJ20 boxer. While there were many improvements and evolutions to the EJ engine series since its introduction in 1989, the clean-slate design of the FA20 allows for a more refined engine. This made possible for the Top view of the FA20 engineFA20 to meet stringent emission and fuel economy requirements with a design that is both simple and more advanced. For example, the FA20’s improvement in variable cam control eliminates the need for both the secondary induction system and a mechanical Exhaust Gas Recirculation (EGR) system to achieve peak performance and emissions compliance.

So what are the secrets behind the quieter, easy-to-service, less-cluttered, higher-performance engine design? TOMEI POWERED set out to answer that exact question. As a company rich in engineering heritage, simply making parts that look good isn’t the goal. Performance through engineering is a must. Hence, as soon as an FA20 engine became available, the first stage of development was initiated. TOMEI POWERED conducted a complete engine teardown and measuring session to build a blueprint of the engine. Comparing this blueprint to that of the EJ20’s allowed TOMEI POWERED to establish a solid basis for identifying potential weak links and areas of opportunity for product development. DSPORT is grateful to TOMEI POWERED for providing this information to the DSPORT performance family.

Dyno graph for the FA20 engineOver 150 lb-ft of torque is an impressive achievement from a 2.0- liter engine. Likewise, hitting the 100- horsepower per liter mark at 7,000RPM is equally impressive.

 

BREAKDOWN OF MAIN COMPONENTS

The intake port size is quite large, similar to what’s typically found in an inline race engine. The intake choke diameter measures 33 mm. On the exhaust port, many similarities are found to the EJ design.

Primary fuel injection is handled by a direct-injection system that delivers high- pressure fuel straight into the combustion chamber. A set of low-pressure port injectors provides additional fuel delivery before the intake valve. This design eliminates valve deposit issues that plague many direct-injection engines.

Displacement Bore Stroke Comp. Ratio Combustion Chamber Vol. Piston Crown
EJ207 1994cc 92.0 x 75.0 *7.9 49.2cc 8.5cc
EJ255 2455cc 99.5 x 79.0 8.2
FE16 1599cc 78.8 x 82.0 10.5
FB20 1995cc 84.0 x 90.0 10.5
FB25 2498cc 94.0 x 90.0
FA20 1998cc 86.0 x 86.0 *12.5 40.3cc 2.7cc
FA20T 1998cc 86.0 x 86.0 10.6
*FA20 MEASURED VALUE (R BANK): 12.7
Here’s a comparison of bore, stroke, compression ratio, combustion chamber volume and piston crown volume across various EJ-, FB- and FA-series engines. The direct-injection nature of the FA20 allows a high static compression ratio of 12.5:1, for superior thermal efficiency. Even the turbo FA20T sports a high 10.6:1 ratio.
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  • gimp4930

    But will it fit in my Hillman Imp?

  • Roy

    Fix your units. You call it 200 lb-ft or torque, when your image shows 200 Nm. Anyone who owns one knows this is closer to 140 lb-ft at the wheels.

    • Tim McDermott

      You are correct. When converted to lb-ft torque it’s actually 151 lb-ft. We’ve changed the spec sheet to reflect the correct figure. Thanks for pointing this out

      • Roy

        Thanks.

  • Matt Collins

    Stumbled on this old article, but if HP = (torque * RPMs)/5252, doesn’t that mean your graph is off, as HP always equals torque at 5252 RPMs?

    • Josh Vance

      Their graph is comparing torque and rpm, not torque and hp.