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How they are made
The cylinders are machined from solid bar 4140 chrome molybdenum alloy steel, with the pistons running directly in the steel bores. The crankshaft is also machined from solid bar 4140 chrome molybdenum alloy steel, the journals of which are precision ground prior to being Magnaflux inspected. The camshaft is provided by a specialist camshaft manufacturer.
Cylinder heads are machined from solid aluminium billet which is purchased directly from one of Australia's largest aluminium companies, as is all alloy used in the engine, thereby providing a substantive quality trail to material source. Conrods are machined from 4130 alloy steel, the 45mm big end bearings are of the automotive slipper type. Under a direct supply arrangement with Honda, various components of the engines are sourced. These items include camshaft followers, and the bendix gear in the starter motor. The ignition coils are also sourced from Honda, but are modified by Jabiru for their own particular application. An integral alternator using rare earth magnets, provides alternating current for battery charging and electrical accessory drive. The alternator is attached to the flywheel and is driven directly by the crankshaft. The ignition system is a transistorised electronic system; two fixed coils mounted adjacent to the flywheel are energised by rare earth magnets attached to the flywheel. The passing of the coils by the magnets creates the high voltage current which is then transported by high tension leads to the centre post of two automotive type distributors (which are simply rotors and caps) before distribution to automotive spark plugs, two in the top of each cylinder head. The ignition system is fixed timing and, therefore, removes the need for timing adjustment. It is suppressed to prevent radio interference. The ignition system is fully redundant, self-generating and does not depend on battery power.
Pistons are General Motors aftermarket made in Australia and are re-machined to include a piston pin circlip groove. They are fitted with 3 rings, the top rings being cast iron to complement the chrome molybdenum cylinder bores. Valves are 7mm (stem dia) which are purpose manufactured for the Jabiru engine in England. The valve gear includes pushrods from the camshaft from the camshaft followers to valve rockers which are CNC machined from steel plate, induction hardened and polished on contact surfaces and mounted on a shaft through an aluminium bronze bush. Valve guides are manufactured from aluminium/bronze, as is found in larger aero engines and high performance racing engines. Replaceable valve seats are of nickel steel and are shrunk into the aluminium cylinder heads. The valve gear is lubricated from the oil gallery. An internal gear pump, direct mounted on the camshaft and incorporating a small automotive spin-on filter, provides engine lubrication. An oil cooler adapter is provided. Most installations require an oil cooler to meet oil temperature limits. The standard engines are supplied with two RAMAIR cooling ducts, which have been developed by Jabiru to facilitate the cooling of the engine and direct air from the propeller to the critical areas of the engine, particularly the cylinder heads and barrels. The fitment of these RAMAIR cooling ducts is a great bonus for the home builder or engine installer, as they obviate the need to design and manufacture baffles and the establishment of a plennum chamber, which is the traditional method of cooling air-cooled aircraft engines. The fact that these baffles and plennum chamber are not required also ensures a "cleaner" engine installation, which in turn facilitates maintenance and inspection of the engine and engine component. So the hard work of engine installation has largely been done for you by the Jabiru design team. RAMAIR ducts are available for tractor or pusher configurations. Special ducts are available for certain installations.
The fuel induction system comprises a BING pressure compensating carburettor. Following carburation, the fuel/air mixture is transported to a small plennum chamber in the sump casting, in which the mixture is warmed prior to entering short induction tubes attached to the cylinder heads. An effective stainless steel exhaust and muffler system is fitted as standard equipment, ensuring very quiet operations, which in the Jabiru aircraft have been measured at 62dB at 1000' full power flyover (for 2200 engine). For those owners wanting to fit vacuum instruments to their aircraft the Jabiru engine design includes a vacuum pump drive, direct mounted through a coupling on the rear of the crankshaft. The Jabiru engine is manufactured within an Australian Civil Aviation Safety Authority (CASA) approved Quality Assurance System to exacting standards. |
Jabiru engines are designed to be manufactured in small batch
quantities using the very latest Computer Numerically Controlled
(CNC) machine tools. The vast majority of the components are
manufactured in Southern Queensland in a network of high technology
small companies. The crankcase halves, cylinder, crankshaft,
starter motor housings, gearbox cover (the gearbox powers the
distributor rotors) and coil mounts together with many smaller
components are machined using the latest CNC machine tools.
The sump (oil pan) is the only casting.
The
engine is direct crankshaft driven and does not use a reduction
gearbox. This facilitates its light-weight design
and keeps maintenance costs to a minimum. The crankshaft features
a removable propeller flange which enables the easy replacement
of the front crankshaft seal and provides for a propeller shaft
extension to be fitted, should this be required for particular
applications.
The crankshaft is designed with a double bearing at the propeller
flange end and a main bearing between each big end; it therefore
does not have flying webs. 48mm main bearings are also of the
automotive slipper type. Thrust bearings are located for and
aft of the front double bearing allowing either tractor or
pusher installation.
The engine is fitted with a 1 kw starter motor, which is also
manufactured by Jabiru and provides very effective starting
in all conditions. The engine has very low vibration levels,
however it is also supported by four large rubber shock mounts
attached to the engine mounts at the rear of the engine. An
optional bed mount is available.