Overhead Cam        > Print chart
9HP / EX27
Product Image
Performance Curve:
Performance Curve
Engine Overview:
EX27 9.0 HP Description

Engine Family Overview:
With nine models ranging from 4.3- to 14-horsepower, the Subaru Overhead Cam Industrial Engines lead the industry in technology, offering more power, less noise and easy, one-pull starting every time. Introduced as the first air-cooled engine line to use advanced chain-driven Overhead Cam technology, the Subaru EX Series provides maximum efficiency, performance and power with minimal noise and emissions. The engine design is extremely compatible and easy to install, and simply exchanges with most existing slant cylinder engines. 
    Class: Air Cooled Overhead Cam Chain Drive Gasoline Engine
    Shaft: Horizontal
    Cylinders: 1
    Displacement: 265
    Cycles: 4
    Fuel: Unleaded Gasoline
    Max HP/RPM (Gross HP): 9.0/4000
    Max KW/RPM: 6.6/4000
    Continuous HP/RPM: 7.0/3600
    Max Torque ftlbs/RPM: 13.74/2500
    Max Nm/RPM: 18.6/2500
    Bore x Stroke mm: 75 x 60
    Compression Ratio: 8.3:1
    Starter: Recoil & Electric
    Dry Weight lbs: 46
    Dry Weight kg: 21
    Length inches (mm): 351
    Width inches (mm): 420
    Height inches (mm): 410
    Fuel Capicity US Gallons (ltrs): 1.59
    Fuel Capacity Fl oz (ltrs): 6.1
    Lube Type: Engine Oil SAE 10W-30, 20W, 30W
    Oil Capicity Fl oz (ltrs): 33.8
    Air Cleaner: Dual Element
    Muffler (type): Low-Noise
    Ignition System: Solid State Transistorized Magneto
    Lube System: Splash
    Oil Sensor: Low Oil Level Optional
    Emission Rating: Tier III EPA/CARB
    Color: Black
    Governor System: Mechanical Flyweight
    Fuel System: Carbureted Float
Key Features & Benefits:
  Chain-Driven Overhead Cam Chain-driven Overhead Cam design offers superior power and performance with an automatic decompression system to reduce the required pulling force by 30 to 40 percent, and ensure starting on the first pull. EX engines start instantly – even at temperatures as cold as -10 degrees C – without any perceptible kickback. 
  Dual Ball Bearing Crankshaft Support Dual ball bearing crankshaft support offers maximum stability under demanding loads.
  Heavy-Duty Piston Rings and a Cast-Iron Cylinder Liner Heavy-duty piston rings coupled with a cast-iron cylinder liner resist wear and ensure a long engine life.
  Spheroidal Graphite Cast-Iron Crankshaft The crankshaft is made of spheroidal graphite cast iron, and the crank pin is high-frequency induction hardened. Both the crank sprocket used to drive the chain, and the gear used to drive the governor gear, are pressed on the output end of the shaft.
  High Power Pent-Roof Design Overhead Cam (OHC) technology and the Pent-Roof combustion chamber allow the Subaru EX engines to use a higher compression ratio of 9:1. The higher compression ratio increases the power produced for a given size engine. It also improves efficiency and overall performance.
  Case-Hardened Steel Timing Chain Case-hardened steel timing chain allows for precision timing and maximum durability.
  Hardened Steel Rocker Arms Hardened steel rocker arms with precision tappet adjusters are used for greater durability and reduce service requirements.
  Automotive Collects and Forged Steel Valve Retainers Subaru EX engines use automotive quality collet valve retainers for longer life.
  Patent-Pending Connecting Rod Dipper The EX lubrication system begins with a patent-pending oil scoop to project the oil to the chain.
  Special Cooling Fins Cast Into Block Cooling fins are cast into both the inside and the outside of the crankcase to utilize every possible cooling area.
  Aluminum Alloy Die-Cast Connecting Rod The connecting rod is a specially heat-treated aluminum alloy die-casting. Its large and small ends function as bearings. A splasher built into the connecting rod lubricates by splashing engine oil. The piston is an aluminum alloy casting with grooves for mounting compression and oil rings.
  Mounting Base Cooling Fins The unique Subaru cooling system extends to the underside of the mounting base. Air is forced over special cooling fins at the bottom of the engine for maximum cooling.
  Cylinder Head 360-Degree Cooling Head cooling is critically important to long engine life. The Overhead Cam design allows for 360-degree air flow around both the exhaust and intake valve stem areas.
  Patent-Pending Cylinder Cooling Fins Air is forced over the large slanted cooling fins on the cylinder for improved cooling performance. This design is patent-pending.
  Optimized-Capacity Rigid Muffler Optimized-capacity rigid muffler and 33 percent fewer moving valve train parts than OHV designs, reduce mechanical noise levels a full 2 decibels below competitive models.
  Patent-Pending Valve Cover Design A patent-pending rocker cover design constantly supplies an optimum amount of oil to the cam shaft and rocker arm even if the engine is inclined.
  Patent-Pending Breather System A patent pending breather system with a pre-separation
passage prevents oil from spouting even if the engine is inclined.
  Hot Spark Ignition System The ignition system is a transistor controlled magneto with the ignition timing set at 23 degrees before top dead center. The magneto consists of a flywheel and ignition coil. To ensure the easy startability of the engine, the step advancing ignition timing system is incorporated in the ignition coil. This system enables the engine to have basically two different ignition timings according to the engine speed.
  NO Special Tools Needed Even though the EX series of engines bring the latest technology, performance, and durability to the industrial air cooled engine market, there are no special tools required to work on them. Most shop tools that small engine mechanics currently own will also work on these engines for service or complete tear down. Subaru engineers achieved their commitment to 'keep it simple', while utilizing the latest technology.
Dimensional Diagram: