High performance A15 build/help.

[Surfez]

Hey guys, looking for some advise for my project A15 motor. Under construction so far, A15 block, twin 40 side drafts, coby extractors opened up at flange, head will be ported "same as" a race head, very fast road cam, ballanced engine etc. Questions outstanding: 1. What weight is recomended for the a12 flywheel to be machined for street use/driving to work & play on weekends? 2. Does anyone have the Mazda 1500cc flat top piston part number... used to up compression in a15 block.

[Bartman]

I've never lightened a flywheel o a weight, just made it smaller till it looked right and run it.
No idea on he part number sorry. (I have the same slugs in my A15)

[mint16]

12pounds is a safe weight for the flywheel with proven reliability.

[chris_g1]

Hey ya a Datsun 1200 a12 flywheel is the lightest from factory. I had one made about 15 years ago from high grade steel 2.5kg worked good lost a lot of torgue but the revs went up to . Before that i used a 1200 one and got it lightened to about 3.5kg running brass button clutch it was good on the road just had to get use to it .
The pistons your after pn(4kry8049 single carb ) or 4mkry8050 twin carb ) these come with steel piston rings ex ACL . What about Daihatsu Charade turbo pistons cheap and factory forged either way you'll need to make the gudgeon pins filly floating . I found out after about 6 engines that filly floating adds reliability and stops the little end from nipping up after a good track day. E13 or E13 Nissan pistons can be used to e13 4mkry2720 e15 4mrky2721 the m in the part number means MOLY rings

[Surfez]

Thanks guys, ended up getting the part number from someone at work with a race engine running them, the number was crossed over to an after market supplier as Ford/Mazda don't supply the pistons I needed, Mazda 1980 1396cc "flat top" pistons to raise compression. The pistons are ordered ex AU and only need the rods boared out 1mm, the block will be boared too as the standard size is not made, so 20tho over for mazda, this will be 60tho out from standard on my engine from 76mm to 77.5mm bore. For the purpose of informing others, The valves may hit the pistons with high lift race cams??? hence I may be creating half crown cuts on he piston top to make space for the valves. I will provide my part number after I confirm he job is completed.