has anyone ever test bored an A15? cause i cant afford a test one and i dun wanna just bore out 40thou. so.. anybody? i wanna take it to the max!

The max may well prove to be dictated by piston availability. Are you in a position to modify Mazda pistons? I think that these use a larger pin as well, so boring the rod may also be necessary.

You can bore them 3mm safely. 4mm on some blocks but if you're going that far you should sleeve it.

Thanks! 3mm it is!

2332owner,
If you bore it out 3 mm, what head gasket are you going to use? Is there one with a big enough bore? I bored my A15 2mm over, and used 79mm Subaru Justy pistons. I used a Nismo head gasket. It was the only one I found that would accomodate a 79mm bore. All stock Nissan gaskets had too small a bore size.

can always get a custom head gasket, might be easier.
copper one maybe.... only about 100 bucks

I've got a Nismo head gasket too for my 79mm bore. Your A15 is 3mm over if you're using 79mm pistons. Stock bore is 76mm. There are a few more companies out there that supply big bore head gaskets but they're all here in Japan that I know of.

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...Silly me! I guess I did go 3mm over. Thanks a bunch.

I wouldn't advise going out to a 79mm bore. As i found out in one of my race motors the cylinder wall between number 2 and 3 cylinder cracked due to being to thin. This motor only lasted three meetings. The only Head gasket that i found suitable was the nissmo. Another good idea is to throw away the head bolts as they do stretch and get studs made up. Havn't blown a head gasket since.

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Head studs, good advice! Depending on what my compression ratio ends up being, I may be supercharging mine. Yes, block thickness can vary. I don't remember how thick my cylinder walls were after boring, but I do remember my machinist telling me he sonic tested them and there was plenty of thickness left in my block. He said they were still thicker than the standard bores of some GM 4 cyl. blocks he had checked!