6G74 3.5L Engine Main Swap details:

      Last updated 3/11/08

      A Specification Comparison Between 6G72, 6G74 & 6G75 engines:

      Description: Symbol/Units 6G72NA 6G72TT 6G74NA 6G75NA STROKER
      Bore: D / mm 91.1 91.1 93 95 96
      Stroke: S / mm 76 76 85.8 90 95
      Crank Offset Radius: R / mm 38 38 42.9 45.0 47.5
      Rod Length: L / mm 140 140 152 152 145
      Piston Compression Height: mm 31.75 31.75 31.75 29.75mm ?
      Deck Height: mm 210 210 228 228 228
      Main Bearing Diameter: mm 60 60 64 64 64
      Rod Bearing Diameter: mm 50 50 55 55 50
      Compression Ratio: 10:1 8:1 9.5:01 8:1? 8:1?
      Piston Pin Diameter: mm 22 22 ?? 22 22
      ROD Ratio(L/S): 1.84 1.84 1.77 1.67 1.56
      Engine Size: cc 2972 2972 3497 3827 4125
      Max Piston Acceleration at 7300 RPM: ft/s*s 92,612 92,612 105,444 111,797 144,524
      Max Piston Acceleration at 8300 RPM: ft/s*s 119,724 119,724 136,311 144,964 155,483

      I have verifed the 6G72& 6G74 information BUT All 6G75 information came from threads on 3SI.org.
      The "STROKER" engine is an idea for maximum displacement using following components:
      6G75 Block Overbored 1mm to 96mm.
      6G75 Crankshaft offset ground from 55mm to 50mm so that 6G72 bearings can be used.
      Custom connecting rods and pistons.
      Offset grinding the crank this much might not be a good idea but 4.1L is 1.1L increase.
      THAT would be a fun engine while it lasted:)

      Using the JSPEC version of CAPS (Mitsubishi Dealer Parts Program) I was able to get the OEM part numbers for almost every part needed for this swap

      Below is a list of Parts only avialable in Japan! so make sure you get these with your JSPEC engine!

      Part Description6G74TT (use these parts)6G74NA6G72TT
      Lower Intake Manifold MD183653 MD183653 (MD152648)
      Oil pan Upper MD190219 MD190219 (MD199562)
      Oil Pan eng Lower MD192397 MD192397 (MD199562)
      Oil pan baffle MD187373 MD187373 (NA)
      Bracket power steering pump mounting MD178139 MD178139 (MB636738)
      Bracket Alternator (big Bracket) MD191579 MD191579 MD162824
      Pulley power steering belt adj MD184357 MD184357 (MD172379)
      Cover Timing belt Forward MD174264 MD174264 (MD192110)
      Cover Timing belt Lower MD189482 MD189482 (MD192109)
      Cover Timing belt rearward MD189484 MD189484 (MD188084)
      Pipe Water pump, in valley MD192394 MD192394 (MD146833)
      Thermostat housing MD173506 MD173506 (MD193877)

      The Following 6G74 parts are required, but are avaialble at US Dealers

      Part Description 6G74TT (use these parts) 6G74NA 6G72TT
      timing belt "MD193875 MD197147" "MD193875 MD197147" (MD319040)
      Rear main seal and Housing MD187561 MD187561 (MD178606)
      Thrust Bearings 6G74 MD197988 MD197988 ?
      Short Block Assy MD182091 MD182091 (MD326222)
      Fuel Rail Loop MD173791 MD173791 (MD162569)
      Crankshaft later years(forged?) MD305941 MD305941 ?

      3000GT/Stealth Twin Turbo parts required

      Description 6G74TT (use these parts) 6G74NA 6G72TT
      Pulley Timing Belt Tensioner MD140071 MD140071 MD140071
      Pulley Timing Belt Idler MD319022 MD319022 MD319022
      Adjuster Timing belt MD319040 MD319040 MD319040
      Water Pump MD972005 MD972005 MD972005
      Intak to Plenum Gasket MD143791 MD143791 MD143791
      Intake Plenum to head Gasket MD164701 MD164701 MD164701
      Gasket Throttle Body MD180361 MD180361 MD180361
      oil pump / front crank seal & case MD190982 MD190982 MD190982
      Oil Filter Housing ? ? ?
      Oil Pump Gasket (not included w/pump) ? ? ?
      Bolt Timing Belt Tensioner MD145360 MD145360 MD145360
      Alternator tensioner pulley, on eng mt MD318474 MD318474 MD318474
      Alternator belt adjuster (to tighten belt) ? ? ?
      Knock sensor MD159216 MD159216 MD159216
      Rear main seal only MD372251 MD372251 MD372251
      head bolt each MD065959 MD065959 MD065959
      Head Bolt Washer MD020733 MD020733 MD020733
      Turbo Exh Gasket MD168266 (NA) MD168266
      Waterpump pipe Oring MD147332 MD147332 MD147332
      Insulator Fuel Injector MD087060 MD087060 MD087060
      Valve Cover Gasket perimeter MD186786 MD186786 MD186786
      Spark plug gasket (3) MD186787 MD186787 MD186787
      Dipstick Oring to pan MD075834 MD075834 MD075834
      Washer for cooling eyebolts (8 needed) MF660064 (NA) MF660064
      Joint Cylinder block (oil feed adpapter rear) MD161392 (NA) MD161392
      Belt, Power steering MD172376 MD172376 MD172376
      Downpipe to turbo Gasket MR188537 (NA) MR188537
      Turbo to Manf Bolt MD168601 (NA) MD168601
      Switch eng oil pressure MD138993 ? MD138993
      Gauge Unit engine oil MD133273 ? MD133273
      Coil Pack MD152648 MD152648 MD152648
      Bracket Alternator (little one) MD158584 MD158584 MD158584
      Gasket Exhaust Manifold (1?,2?) MD168115 MD168115 MD168115
      Valve Cover Rear MD186132 MD186132 MD186132
      Knock Sensor Bracket MD155544 MD155544 MD155544
      sensor Crank positon ? ? MD187066
      sensor Camshaft Postion ? ? MD187067
      Oil Pickup tube and strainer MD158618 MD158618 MD158618
      Bracket A/C compressor Mounting MR149149 MR149149 MR149149
      Plate Transmission to Engine MD199579 ? MD199579
      oil feed tube -RH (Rear?) MD161898 (NA) MD161898
      oil feed tube -LH (Front?) MD174793 (NA) MD174793
      Eyebolt Turbo Oil lines MF650102 (NA) MF650102
      copper gasket oil lines turbo MF660063 (NA) MF660063
      Water feed Front, (RH) MD194061 (NA) MD194061
      Water Return Front(RH) MD153689 (NA) MD153689
      Water Feed Rear (LH) MD158758 (NA) MD158758
      Water Return Rear(LH) MD153691 (NA) MD153691
      Eyebolt cooling (4 needed MS650013 (NA) MS650013
      Fuel Rail MD319816 MD319816 MD319816
      Fuel Pressure Regulator "MD164615 MD322989" (MD322988) "MD164615 MD322989"
      Fuel Injector MD164888 (MD189021) MD164888
      bracket water pump to lower intake MD133859 MD133859 MD133859
      Engine mounting bracket rear MD166609 (MD190217) MD166609
      Roll stopper drivers alum MB870005 (MB910818) MB870005
      Stay T/M mount Front ? MD176109 ?
      Stay T/M mount Rear ? MD306884 ?

      Another advantge of the 6G74 block is that the deck height is 18mm higher. The extra deck height provides extra room for longer connecting rods. Below is a visual model showing how longer rods reduce connecting rod accelleration and increase piston dwell at TDC

      The 3 pictures below show 3 rod and pistons combinations.

      1. 12mm shorter rods (140mm) with 12mm longer wrist pin location (43.5mm)

      2. 4mm longer rods (156mm) with 4mm shorter wrist pin location (27.5mm)

      3. Stock 6G74 rods (152mm) with stock wrist pin location (31.5mm)

      This was just to show that at TDC the piston sticksout above the head 2.4mm in all combinations.

      Now I turn the crank 25degrees and discover that in this position the piston has moved more with shorter rods.
      You can also see that the rod angle is greater with shorter rods

      rodlength25stock rodlength25deg4mm.jpg

      1. Piston Acceleration of a 6G74 4.0L Strokers at 7300RPM is very close to 6G72 Engine at 8300RPM

      Please Note this Webpage is still under construction!

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