Difference between revisions of "Astron II"
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| caption = Astron II in a first generation Magna | | caption = Astron II in a first generation Magna | ||
| manufacturer = Mitsubishi Motors Australia Limited | | manufacturer = Mitsubishi Motors Australia Limited | ||
| − | | aka = 4G54 | + | | aka = 4G54, 4G54B, G54B |
| production = 1985 - 1996 | | production = 1985 - 1996 | ||
| predecessor = [[Astron]] | | predecessor = [[Astron]] | ||
| Line 44: | Line 44: | ||
==Original Astron II== | ==Original Astron II== | ||
| − | 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, Triton | + | 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]]. |
| + | |||
| + | 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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{{clear}} | {{clear}} | ||
==Revised Astron II== | ==Revised Astron II== | ||
| − | [[Image:2g_head.jpg|200px|right|thumb| | + | [[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 | + | [[Image:2g_rollers.jpg|200px|right|thumb|Rocker gear on the revised Astron II]] |
| − | [[Image:2g_piston.jpg|200px|right|thumb| | + | [[Image:2g_piston.jpg|200px|right|thumb|Astron II dished pistons used in the TS Magna (M9 Head)]] |
| − | + | 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. | |
| − | + | 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. | |
| − | + | 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 and M7 were used in the TR Magna. | |
| + | |||
| + | With the release of the [[Second Generation Magna|TS Magna]], the Astron II was modified once again with a switch to the M8 and M9 head which used swirl-type "kidney shaped" combustion chambers with dished top pistons (to match the combustion chambers). These promoted better mixing of air and fuel, less detonation (knocking) and a better flame front. | ||
| + | |||
| + | The M6 through M7 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. | ||
| − | |||
{| | {| | ||
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|Aluminum Alloy with hemispherical combustion chambers and crossflow design | |Aluminum Alloy with hemispherical combustion chambers and crossflow design | ||
|- | |- | ||
| − | |'''Port | + | |'''Inlet Port Diameter''' |
|42.00 mm | |42.00 mm | ||
|- | |- | ||
|'''Inlet Valve Diameter''' | |'''Inlet Valve Diameter''' | ||
|46.00mm | |46.00mm | ||
| + | |- | ||
| + | |'''Exhaust Port Diameter''' | ||
| + | |40.00mm | ||
|- | |- | ||
|'''Exhaust Valve Diameter''' | |'''Exhaust Valve Diameter''' | ||
