You can buy A10 flat tops 1.0 1.5 oversize here in Australia . Pretty sure their same size as A12 .
That might bring you upto 74 / 74.5 mm

http://www.swmotorsport.com.au/index.php?cPath=9_59

DD , I am confused.
What does flat tops offer besides shape ?? Isnt it the compression that counts ??

These high comp 11:1 D16 pistons have pin height 19mm length 137mm compression height of 30mm
and come in 75mm/ 75.5/ 75.75/ 76

https://www.ebay.com.au/itm/NIPPON-RAC ... 9d4373:g:FWgAAOSwGvhT5REe

The original poster -- rallytwit -- is a seasoned racer. He is looking for flat-tops for A12A engine. He also stated twice that he doesn't want custom pistons, which those D16 pistons are

Unfortunately A10 pistons (73mm bore) won't fit the A12A engine (75mm bore)

In general flat-tops are more powerful than dish pistons given the same compression ratio. For example: 10:1 with dish and small combustion chambers make less power than 10:1 with flatties and medium combustion chambers. They can take more spark advance, return more power and more fuel economy, and are less prone to pinging detonation so can use lower octane fuel. See our tech article Quench

I'd look at Nissan K15 pistons -- off-the-shelf flat-tops, correct pin height and inexpensive. Look like A12 GX flat-tops but with 75.5mm bore

Dave are the K15 pistons heavier? I seem to recall looking at forklift pistons years ago but they were heavy.

As for quench; on the two stroke bikes and my F500 it's one of the things that are checked when building a motor.

DD didnt even know the K15 engine existed! its not anywhere online that I could find

do you know the bore and stroke or any pictures of it as I can only find the k21 and k25

Its a good looking engine and revs to 3000 rpm for max hp and 1600 max torque maybe slugs
are not compatible for high rpm?

pistons are cheap
https://www.alibaba.com/product-detail ... 017115.156.54c81adb9Q2nYF

looks like a nice head too with alloy rocker cover standard
you could fill the top of the extended port area with weld
and port even higher than A series heads
http://www.k21engine-parts.co.uk/contents/media/l_11040-fy501a.jpg



awesome downdraft ports!!!!
https://www.youtube.com/watch?v=BOCLhFDhj6Q

Yeah it looks like a L engine with pushrod version of the cylinder head (L-type block and L-type port layout). Appears to only be used by forklifts

The cam timing gear cover looks like A-series

Nissan K15 pistons

whats the bore and stroke of stock K15?
Ive always thought the chevy hemi 2ltr L4
was the only option to emulate a good OHV
but with more capacity than the A series.

Toyota guys are lucky the 7k series was
1,781 cc or 1.8L and able to change to
Liteace 2.0 & 2.2 ohv Y series

from another members post

"Last A14 I built in the early 90s used some sort of Mitsubishi piston - looks like it was a G32B piston. 76.9mm, 33mm Comp ht and 19mm pin. It was about .040" oversize for the A14 and with .020 or .030" (.5-.75mm) milled off the crown - really just the outer edge to get the comp height down. Trawl through an ACL catalog... Way cheaper than getting stuff made."

Yeah those Mitsu 4G32B pistons are dished. There is a pic in our Overbore tech article

So what North American car uses 4G32B engine/pistons?