Difference between revisions of "Astron II"

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The Original Astron II was fitted to the all [[First Generation Magna]]s (TM-TP), carburetted [[Second Generation Magna]]s (TR-TS), the GN Sigma, [[Second Generation Triton|Triton]] ME through MJ and Pajero [[First Generation Pajero|NE]] through [[Second Generation Pajero|NH]].
 
The Original Astron II was fitted to the all [[First Generation Magna]]s (TM-TP), carburetted [[Second Generation Magna]]s (TR-TS), the GN Sigma, [[Second Generation Triton|Triton]] ME through MJ and Pajero [[First Generation Pajero|NE]] through [[Second Generation Pajero|NH]].
  
These typically had the numbers M1 through M5 cast into the head and V5xx engine numbers.
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When used in the Magna, these engines typically had the numbers M1 through M5 cast into the head and V5xx engine numbers.
  
 
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==Revised Astron II==
 
==Revised Astron II==
[[Image:2g_head.jpg|200px|right|thumb|Second Generation Astron II combustion chambers]]
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[[Image:2g_head.jpg|200px|right|thumb|Revised Astron II combustion chambers used in the TS Magna (M9 Head)]]
[[Image:2g_rollers.jpg|200px|right|thumb|Rocker gear on the Second Generation Astron II]]
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[[Image:2g_rollers.jpg|200px|right|thumb|Rocker gear on the revised Astron II]]
[[Image:2g_piston.jpg|200px|right|thumb|Second Generation Astron II dished pistons]]
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[[Image:2g_piston.jpg|200px|right|thumb|Astron II dished pistons used in the TS Magna (M9 Head)]]
The '''second generation [[Astron II]]''' was fitted to fuel-injected TR and TS models.
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A revised Astron II was fitted to fuel-injected TR and TS models. The revised Astron II used roller rockers, a higher compression ratio (9.2:1 up from 8.8:1), larger inlet ports (42mm up from 40mm in the original), a knock sensor and a self-adjusting [[balance shaft]] chain adjusting mechanism as fitted to late model original Astron IIs.
  
The revised Astron II included "kidney shaped" combustion chambers in the cylinder head, roller rockers, dished top pistons and the self-adjusting [[balance shaft]] chain adjusting mechanism fitted to late model Astron IIs.
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These changes increased power to 98 kW at 4750 rpm (103 kW when running on premium unleaded) and torque rose to 212 Nm at 3750 rpm.
  
The quickest way to identify the second generation Astron II from the original is to look for a knock sensor under the injection plant. First generation Astron IIs do not even have a hole for it. Other methods are by it's engine number (prefixed by W531, W532) or by the casting number on the head. Second generation heads are marked "M9".
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Revised Astrons can be identified by their knock sensor situated under the fuel injection plant (original Astron II's do not even have a hole for it), its engine number (all are prefixed by W531 or W532) or the casting number on the head (M6 through M9). The M6 through M8 were used in the TR Magna.
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With the release of the [[Second Generation Magna|TS Magna]], the Astron II was modified once again with a switch to the M9 head which used "kidney shaped" combustion chambers with dished top pistons (to match the combustion chambers).
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The M6 through M8 head is said to be the best Astron II head - using the largest valves, ports and having good flow characteristics. The M9 head while similar has less desirable flow through the intake ports due to the shape of the combustion chamber.
  
As a result of these modifications the compression ratio raised to 9.2:1 and power rose to 98kW @ 4750 rpm (103 kW if ran on premium unleaded thanks to the knock sensor included as part of the engine management system). Torque also rose to 212Nm @ 3750 rpm.
 
 
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Revision as of 21:33, 22 December 2018