- 12mm shorter rods (140mm) with 12mm longer wrist pin location (43.5mm)
- 4mm longer rods (156mm) with 4mm shorter wrist pin location (27.5mm)
- Stock 6G74 rods (152mm) with stock wrist pin location (31.5mm)
- Piston Acceleration of a 6G74 4.0L Strokers at 7300RPM is very close to 6G72 Engine at 8300RPM
-
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 |
NOTES:
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 Description | 6G74TT (use these parts) | 6G74NA | 6G72TT |
|---|---|---|---|
| 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.
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
COMMENTS:
Please Note this Webpage is still under construction!
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