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"VGs are very much like L-series in that you can mix and match lots of parts. ALL North American VGs have the same stroke and they all have the same size bearing journals. I do not know about the VG20 found overseas. The VG30E block cannot be bored to use VG33 pistons, the cylinder walls are too thin. The magic formula to build a VG34 is this: Bore a VG33 block .060 over. Use *stock* 1995 Infiniti Q45 pistons, rings, and wrist pins. Use VG30ET rods with custom, larger I.D. small end bushings as the Q45 wrist pins are 1mm larger. You can use any SOHC VG crank (they are ALL cast), but there are differances in front snouts and related accessories so use one you've got all the parts for. Avoid any SOHC VG crank that's been run with a serpentine accesory belt as these tend to break off the crank snout! The above VG34 combination is the one used in the off road trucks. If I remember right this bottom end comes out to 10.5:1 compression, perfect for a street motor. Sly said a VG34 with "good" cams and stock heads will make 250hp on 93 octane in street-trim. With port work and the "right" cams and intake a VG34 can make 300hp on pump gas. Sly says that no matter what you do they won't make power over 6500rpm as the displacement is too big for the head design. The question I've never heard answered is what happens when you turbo a VG34? I don't know anyone that's done it so I don't know what the limit is. I'm guessing the crank will come apart first. I've been told by many that SOHC VG cranks are short lived when 350hp is exceeded. It is possible to use the forged DOHC crank in a SOHC block but it requires a custom flywheel and messing around with a few things to make it go together. It's relatively painless but I've only done one so far. If you are thinking about building any VG be warned that they are difficult and expensive just to rebuild stock. Many automotive machine shops cannot hold the tolerances neccesary to make a VG live, especially if it's warmed-over. Rebuild parts are also expensive, but then they should last 200k miles." from an S12 forum
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