had mine cut down aswell, seems that there is enough left. Probably have to wait and see what happen :)

What about E15t pistons , will still need to be machined down but the whole top of the piston is dished and would lower comp. great for forced induction. Thats what i was going to do to my a15t before i decided to go CA power

Any update on this thread? Success or failure with cut down A14 pistons? How much would a set of flat top A15 pistons be anyway?

Only issue with A15 pistons in South Africa is availability!

I believe Mazda E5 or something pistons is the norm to use for A14 with A15 crank conversions.

i've got a set of new a15 (77.5mm)cast flat top pistons & rings, 18mm pins, rods to suit(been bushed),close & honed rods, new bolts,pin buttons to suit(floating little ends), and balanced, NOTE; will need valve reliefs if running big cam. asking $850 if anyone interested.(they are NOT machined down one). cheers

The problem is far more heat/flame exposure to the top ring (that is IF thinning out the crown thickness doesn't do it in in the first place) the top ring is the only 'true' compression ring.. The second ring, is mostly oil control, even though it's called a compression ring. It's why ultra short pistons only have one compression ring and do ok (it's preferable to do that than to narrow the piston crown too much).

It's the sort of thing that might survive in a drag race engine, or MAYBE a circuit racer doing only short sprints, but it's a bad bad bad bad bad idea for anything you want to clock up decent miles on. Top ring life pretty much = engine life (or at least useful engine life) at least if everything else holds together. thinning the piston top that much will accelerate top ring demise. No question of it. Which means it'll be putting contaminants past the rings quicker, and speeding up ring/bore wear.

I'm not suggesting you'll only get 500 miles out of the thing, but it certainly isn't an option where you'd expect normal engine life (i.e. into the hundreds of thousands of km's with proper oil/change/maintenance).

I dunno what options everyone has out there, but I'll put it another way - if I couldn't get a15 pistons, but a14 gear was plentiful, tben I'd simply look at building an a14 instead of a 'compromised' a15

We have built two A14 engines with A15 crank, A14rods and pistons without machining the pistons, instead we have used the A14 "pollution" head with bigger combustion chamber! With this combination the squisharea is almost zero and the compratio is suitable for a mid tune street engine. With a 290degree cam and twin carbs, extractors and electronical ignition this engine have shown good results in the dyno, 128hp! I don´s recomend this for a race engine nor a longmiler but for a cruiser slash weekendracer this is a good setup, these engines has been driven hard without big problems. My friend bent some valves when the throttle jammed at full speed.

Marcus

Been done....took the top off number 4 after maybee 5000k's
NEXT?

For me I'm just thinking aloud and I only ask because you guys are such an oricle of Datsun knowledge.

The inspiration was reading about e85 and the idea that with this fuel or water injection you can dramatically increase the compression ratio. Made me wonder how feasible it would be with a piston swap.

Cheers

What about GA16de pistons? Anyone know the dish volume. They're 76mm diameter with a comp height of 29.1mm and a pin size of 19mm. That'd put it 0.9mm down the hole.