I have been debating what motor to turo charge for my next project, A12/14/15. I have one of each. I'm thinking that a tubo motor should be revving real hard, so I'm tempted to do it to an A12. I have some brand new +0.20 A14 pistons, But I dunno If A12 blocks can be bored that far. What can you guys tell me?

acording to info dodgeman gave me, an early a12 block is ok to 76mm (standard a14 or a14 pistons) but any more is a gamble. same for late model blocks (b210 onwards) but their design is same as a14-15 blocks so i think it should be ok. check with an engine builder.

I used to run mine at 77mm (for 1303cc)
I had to get them sonic checked, and find one without core shift...
It would ususally take 4 or 5 to find a good un..

I originally bored my 1200GX engine to 76mm & used A14 pistons. That only lasted about 100,000 miles, so i bored it again, this time to the first oversize for the A14, which is 76.5mm. This too lasted only a paltry 100,000 miles, so i will be boring it yet again to the next oversize of 77mm. With care, it should last for the rest of my driving lifetime.

there is already a 1200 coupe running around here with the original type 1200 engine at 77mm.
Nissan at one time produced a 76.8mm forged piston for racing use, for use in the A12 engine, so you should be safe at 76mm & i, personally, wouldnt hesitate to go to 76.5mm.
Chris

I guess we've all but given up encouraging people to use the search function? I know, it's quicker and easier to make a new post.

I've noticed some forums (who have active moderators) delete or move repetitive posts, which seems to aid archive search and retrival.

If you want a brand new virgin block that has never been used I have one for sale...It was for a rainy day but it taking up space. It has no bearing caps or anything just a bare block.

No thanks, if I do go down this road, I have an a12 with 104000 kms on it. Just barely run in.