Differences Pg01

The suspension refinements that worked so well on the Peter Wherrett Special have been carried over to the Turbo. These include; heavy duty front springs, retuned front struts and revised front strut seat spring position (to increase tyre clearance).

The 3.42:1 ratio of the 2.6 litre models is used in lieu of the standard 2.0 litre manual models 3.7:1.

This model is fitted, as standard equipment, with disc brakes at the front and rear. The disc rear brakes are the same as those recently released on the Peter Wherrett Special and as option 810.

The clutch pressure plate and driven plate are unique to the Turbo engine. The clutch pressure plate features a higher clamping load. The clutch pedal pivot support has been revised to accept the higher pedal efforts required to operate the heavier duty clutch assembly.
Clutch adjustment on this model has been simplified by re-introduction of a cable with a 'threaded' outer cable housing and lock nuts. This cable also contains an improved inner cable and liner and will be added as a running change to all Sedan and Wagon models. Extra heat resistance capacity has been built into these cables to cope with the higher underhood temperatures that this model will experience.

The cooling system includes the larger radiator of the 2.6 litre model supplemented by an additional electric fan situated in front of the radiator. Its operation is controlled (via a self earthing thermal switch in the top hose water outlet elbow) by radiator top tank
temperature and therefore after prolonged high speed on boost the electric fan comes into operation. This fan may continue to operate after the engine has been switched off. This is quite normal and ensures adequate cooling in "hot soak" conditions. Hot air is exhausted from the engine compartment via the two vents in the engine hood.
The thermal switch operates the fan when the water temperature exceeds 95 to 96°C. The vehicle has the 82°C thermostat in lieu of the 90°C assembly used on the standard 2.0 litre model.
Additional panels have been fitted to the upper radiator yoke panel and the lower grille support to improve airflow through the radiator and air conditioner condensor.

The Turbo uses a heavy duty 12 volt 13 plate 69 amp hour battery that can be identified by a blue cover and blue vents. Use of this capacity battery is essential to cope with the 'ignition off' operation of the front mounted cooling fan. A higher output 55 amp alternator is also fitted. The alternator housing is slightly longer than the previous model alternators and requires an additional spacer washer at the lower attaching bolt. All other components are common to other models, i.e. wiring, adjusting strap, etc.
This alternator is the same as used on the Valiants.
Because of the unique requirements of the turbo charged engine and its sensitivity to spark advance, a distributor with unusual features is provided. Essentially it consists of an electronic ignition distributor body and pick-up assembly with a conventional centrifugal advance mechanism and a special vacuum advance/pressure retard unit. In this unit, vacuum or pressure (during boost) from the engine intake manifold is introduced into the assembly chamber and causes diaphragm movement such that
vacuum yields spark advance and pressure yields spark retard. This ensures optimum spark timing under all driving conditions and minimizes the risk of detonation.
A green indicator light has been included in the instrument cluster to advise the driver when the turbocharger is operating at positive pressure. This light is operated from a self earthing switch located in the rear of the inlet manifold, the switch opens from
5 to 15.5 kPa.

The performance of the 2.0 litre Astron engine has been increased dramatically, however it stands as testimony to the strength of the standard 2.0 litre engine that only the following changes were necessary to the Turbo version.

The 2.6 litre camshaft has been used in the Turbo to provide improved low and mid range performance.
Connecting rod bearings for the Turbo are made from tri-metals whereas the standard two litre engine uses aluminium/tin bearings. Aluminium/tin main bearings however carryover.
Machining of the cylinder head combustion chambers and the use of special imported pistons achieve a compression ratio of 7.8:1 (standard 2.0 litre comp.ratio is 9.5:1).
The Turbo cylinder head can be identified by the letter T stamped on the head adjacent to the ignition distributor.
Compression pressure for this engine is 1030 plus or minus 70kPa.
The engine oil pan has a fitting for oil return from the turbocharger.

Lubrication is essential to efficient operation of the turbo charger. Engine oil is pressure fed via an adapter from the oil filter to the
upper part of the turbo unit, flows through the bearings and finally drains back into the engine oil pan.
Apart from lubricating the moving surfaces, the oil services a very important function in removing heat from the turbo unit. To ensure that the oil is adequately cooled, an additional oil cooler is mounted in front of the radiator. Oil is circulated through the cooler only if the temperature rises above a predetermined level. Control is via a wax element plunger type thermostat in the adaptor. This thermostat starts to open at 82°C and is fully open at 88°C.
To allow for the increased engine oil capacity, the dipstick has been recalibrate. The dipstick guide tube has been reshaped to provide better access to the dipstick.