Dyak
Sunbeam Dyak in an Avro 504K
Type	Piston inline aero-engine
Manufacturer	Sunbeam
First run	May 1918
Major applications	Avro 504
Variants	Sunbeam Pathan

The Sunbeam Dyak was a British inline six-cylinder, water-cooled, twin updraft carburettor engine.

It had an aluminium sump, block and cylinder head, and is an overhead camshaft design with two valves per cylinder. The output was approximately 106 horsepower (79 kW). The engine was started by turning a geared crank handle in the cockpit. The diesel-powered Sunbeam Pathan was developed from this engine.

The first Queensland and Northern Territory Aerial Services (QANTAS) aircraft in Australia (an Avro 504K) was fitted with a Sunbeam Dyak engine by the Australian Aircraft & Engineering Co. Ltd. in Mascot, New South Wales.^[1]

Data from Lumsden^[2]

• Type: 6-cylinder, upright, inline engine
• Bore: 4.72 in (120 mm)
• Stroke: 5.12 in (130 mm)
• Displacement: 538.26 cu in (8.8 L)
• Dry weight: 399 lb

• Valvetrain: Overhead camshaft, two valves per cylinder
• Cooling system: Liquid-cooled
• Reduction gear: Direct drive, left-hand tractor

• Power output: 100 hp at 1,200 rpm (takeoff power)
• Compression ratio: 5:1

Comparable engines

• Benz Bz.II

Related lists

• List of aircraft engines

Wikimedia Commons has media related to Sunbeam Dyak.

• "Sunbeam Overhead Cam Engines". Wolverhampton Museum of Industry. Archived from the original on 1 June 2008.