The Neptune (or 4G4x) family of engines were a family of inline 4 cylinder engines featuring cast iron blocks, alloy heads and are of a overhead valve (pushrod) design. They were produced from 1971 through 1979.
The Neptune family replaced the JH4 which Mitsubishi had been building under licence from Willy's. The engine was shortlived, with it unable to meet increasingly tougher emissions regulations in the 1970s, leading to it being replaced by the Orion.
The 4G41 is a 1.4 Litre engine displacing 1378cc with a 76.5mm x 75.0mm bore and stroke. It has a compression ratio of 9.0:1 and produced 64 kW at 6000rpm and 115 Nm at 4000 rpm. It saw service in non-Australian Galants, Delicas and in FG14 forklifts.
The 4G42 is a 1.2 Litre engine displacing 1187cc with a 71.0mm x 75.0mm bore and stroke. Using a compression ratio of 9.0:1, it produced 51 kW at 6000rpm and 95 Nm at 4000rpm. It saw service in non-Australian A71 model Lancers.
|MITSUBISHI PETROL ENGINES|
|3A9x||3A90 3A91 3A92|
|Orion||4G11 4G12 4G13 4G15 4G17 4G18 4G19 G4ED|
|Sirius||4G61 4G62 4G63 4G64 4G67 4G69|
|Astron||4G51 4G52 4G53 4G54|
|Astron II||Original Revised|
|Saturn||4G30 4G31 4G32 4G33 4G37|
|4G9x||4G91 4G92 4G93 4G94|
|4A9x||4A90 4A91 4A92|
|4B1x||4B10 4B11 4B11T 4B12|
|6G7x||6G71 6G72 SOHC 12v 6G72 SOHC 24v 6G72 DOHC Early 6G74 Late 6G74 Ralliart 6G74 6G75|
|6A1x||6A10 6A11 6A12 6A13|