Combination Octane Rating Unit Engine


This laboratory test method covers the quantitative determination of the knock rating of liquid spark-ignition engine fuel in terms of Research Octane Number and the Motor Octane Number, including fuels that contain up to 25% v/v of ethanol. The sample fuel is tested using a standardized single cylinder, four-stroke cycle, variable compression ratio, carbureted engine run in accordance with a defined set of operating conditions.

  • Easy conversion between MON and RON methods is accomplished by use of the dual speed motor, with no need to change the flywheel
  • The dual speed motor with slide base steadily provides constant octane engine speeds as per ASTM D2699 and D2700 methods during operation
  • The engine crankcase is designed with high strength and rigidity for various fuel types to ensure long service life and carefree operation
  • The cylinder assembly allows the compression ratio to be changed by adjusting the cylinder height, which is adjusted by the electric motor assembly
  • The dial indicator is installed on the octane engine for direct reference to the cylinder height
  • The compression ratio and ignition timing are displayed directly on the operating panel, and it displays the compensated reading for barometric pressure
  • With digital knock signal adjustment, combustion knock is converted into a stable and accurate analog signal to improve accuracy and efficiency
  • Through the engine's safety system, the engine auto-stops with various fault indications
  • With the exhaust surge tank system, the engine eliminates resonance pulses and back pressure for more consistent and accurate results
  • The intake air humidity equipment regulates the moisture content of the intake air as per the ASTM specifications

The K90901 Standard Model Combination Octane Rating Unit is the latest model of octane engines with many easy-to-use features including automatic functions and enhanced documentation capabilities, conforming to the latest ASTM D2699 (RON) and ASTM D2700 (MON) test methods.

Through the engine's operating panel, the parameters are adjustable according to the ASTM D2699 and D2700 specifications. The professional and clear design of the operating area makes the octane rating operation convenient and the data is easy to read and record. The auto-setting function of the octane engine effectively simplifies operational procedures and improves the efficiency of octane testing. The operating panel is equipped with a protect system and push-button switches to avoid improper operation. 

Conforms to the specifications of: ASTM D2699, ASTM D2700; ISO 5163, ISO 5164, IP 236, IP 237

Working Range: Up to 120 Octane Number

Operation Conditions:

    Cylinder Jacket Coolant Temperature: 100 °C ± 1.5 °C (212 °F ± 3 °F)

    Crankcase Oil Temperature: 57 °C ± 8.5 °C (135 °F  ± 15 °F)

MON Conditions: 

    Engine Speed: 900 ± 9 rpm

    Ignition Timing: Variable as cylinder height is changed

    Intake Air Temperature: 38 °C ± 1 °C (100 °F ±  5 °F)

    Intake Mixture Temperature: 149 °C ± 1 °C (300 °F  ± 2 °F)

RON Conditions: 

    Engine Speed: 600 ± 6 rpm

    Ignition Timing: 13° BTDC

    Intake Air Temperature: 52 °C ± 1 °C (125 °F  ± 2 °F)

Engine Information:

    Compression Ratio (C.R.): 4:1 - 18:1

    Cylinder Bore (diameter): 82.55 mm (3.250")

    Stroke: 114.30 mm (4.50")

    Carburetor Venturi (Research): 14.30 mm (9/16")

    Intake Valve Clearance (Hot): 0.20 mm ± 0.025 mm (0.008" ± 0.001")

    Exhaust Valve Clearance: 0.20 mm ± 0.025 mm (0.008"  ± 0.001")

    Intake Valve Opens Timing: 10° ± 2.5° ATDC

    Intake Valve Closes Timing: 34° ABDC

    Exhaust Valve Opens Timing: 40° BBDC

    Exhaust Valve Closes Timing: 15° ± 2.5° ATDC

    Crankcase Oil Pressure: 172 kPa - 207 kPa (25 psi to 30 psi)

Compression Ratio Adjustment: Motor-driven 

Compression Ratio Display Device: Dial Indicator & Digital Counter

Engine Speed Conversion: Dual-Speed Monitor

Carburetor: Four-Bowl Falling Level (with a cooling function)

Ignition Timing Display: Digital (Auto-set)

Crankcase Pressure Display: Yes

Crankcase Oil Heater: Yes

Oil Temperature Display: Yes

Air Humidity Control Apparatus: Yes

Unit Protection Systems: Yes

lxwxh,in.(cm): 68x42x58 (172.72x106.68x147.32)

Net Weight: 2250 lbs (1022 kg)

K90900-PRF-T ASTM Primary Reference Fuel, Toluene, 55 Gal.

K90900-PRF-I ASTM Primary Reference Fuel, Iso-octane, 55 Gal.

K90900-PRF-H ASTM Primary Reference Fuel, n-Heptane, 55 Gal.

K90900-PRF-O ASTM Primary Reference Fuel, Octane #80, 55 Gal.

K90900-TK Tool kit to assist in the maintenance of the Octane Rating Unit

K90900-S Spare Parts to support the "Combo" Engine

Below are links to tutorial videos for this product