Ive heard locally in japan the Honda EP crank was a cheaper way than going billet
for a stroker of 86mm as the EP model engines is 77mm bores the mains almost match.
This is pretty extreme and there are other is the D series in various strokes which
is 75mm bores all alloy engine but also mains almost match.
The areas which would help the A series live longer in between rebuilds vs twin cam
and other modern sohc engines is all expensive.
eg.
hollow billet roller cam
roller rockers
100gsm lighter rods
exotic lightweight valves and retainers
knife edged crank

All above is more expensive than setting up a sohc or dohc head
on an A series bottom end and with all stock bar the pistons
a mazda 16v or vauxhall 16v head would free up 30-40 more hp

D I've been pouring through the various spec sheets and noticed a few bikes that are close but haven't really found anything. Several months ago I think I found some Honda bike pistons but the price was more than just ordering what I needed.

If you have detail on what Honda crank I'd be curious as to the details, not that I would do anything with it.

I also looked at Mazda GLC pistons, Rockauto had some that were 78.75mm that worked out to $45 for a set with rings. Some minor machine was needed but the total would be around $250 for parts and labor.

The pin height on RB20 piston seems to be way off for an A15, it seems like milling 2mm off the top of the piston wouldn't be fesaable.

All said and done the larger bore isn't a huge boost, probably no more than 10hp but realistically more like 5-7.

Tom

Rods are too heavy compared to A series which are ample
sides need to be brought down a smidgen on the big ends

Some speedway guys use z1000 or other bike pistons which
are the lightest and early cbr ones. There is even some
guys running an early honda crankshaft equivalent to A14
but much lighter stock and lighter than anything lightened.
They use bike rods and pistons as well as acceleration is
the main thing with these single speed cars competing
with superior bike engined cars.

The rods do bolt in but they hit the oil pan due to the bigger bolts/big end. It is only a slight interference but worth mentioning.

I've thought the same. I have a set of ca16de pistons. The raised tops may have to be machined with flycuts for the valves and matched to the chambers. The pins suit fully floating conversion of the rods. Nice pistons with drilled rather than slotted oil returns = stronger for higher revs. Need a bit of calculation for the compression ratios. I think they might be the same piston fitted to the 2 litre RB motors.

The rods also look like they'll fit and they're much beefier that the a15 rods.

Hi Tom,
Don't know about the CA16 piston but the Mada MX5 ( Miata ) pistons go straight in and I believe the CA rods go onto them.
Cheers
Dave

So in my never ending and usually unsuccessful ideas for,cheap upgrades I noticed CA16 pistons are 78mm with a 30mm pin height. These would work nicely for my spare A15. It also occurred to me if it was possible to use the CA16 rods the only machining needed would be boring the block.

With that said CA16 pistons don't appear to be very available, has any of the gang investigated this option?

Tom