1G Standard forged or .20 over?

[AlmightySo]

Hey I just wanted to clarify something my machine shop suggested to me.
He said my block is std bore & that I should go .20 over since my goal is to run high boost. Approx 30psi max for the build.
Should I stay std and order std sized forged pistons or go .20 over? Thanks

 

[ThunderChild]

Running high boost doesn't determine whether you should over-bore your block. If the block has cylinder taper, out-of-round or ring ridge toward the top of the cylinder are a few of the reasons you'd need the block machined.

Most likely, the block is worn and will need a fresh surface for new rings to seat, meaning a bore and hone will be required.

You might want to find a shop that's more familiar with 4g63's.

 

[95REGF150]

Going 0.020" over or not really has nothing to do with how much boost your going to run. You bore the cylinder if the piston to wall clearance has become too large due to wear or the hole has gotten out of round for some reason. If you have a standard bore block that can be honed to the proper piston to wall clearance for forged pistons and is not out of round then I would say stay with the standard bore. Why pay to have it bored if you don't need too? The 0.020" is not going to gain you anything noticeable in displacement. However, if your machine shop is recommending to you to go 0.020" over it is probably because the bores are getting worn and feels that it would be good to start in fresh material.

 

[AlmightySo]

I wanted to stay std but what you said makes sense. I'll ask him about the roundness, block still had cross hatches on each cylinder (6bolt) & one more question if you guys wouldn't mind. What compression ratio do you guys recommend? I've been looking for info on the 8.3:1 but I can't find anything useful.
I have 93 octane at almost every gas station here in delaware

& @tametalon92 he's said they've worked on 4g63's before. I asked if they had a torque plate aswel for our cars, and they do. Not to many machine shops in my area