16V/20V pistons

[woper]

Hi,

Does anyone know, will 20V pistons work with 16V head?


Cheers!

[Ivan141]

uhmm..

no, the valve reliefs are all wrong

[oldeskewltoy]

depends on what you mean by work.... they can be used... but if the timing belt breaks the engine is no longer non interference... Also the 20V pistons can develop hot spots because the valve reliefs are so close to the pistons edge, but in all but the most extreme conditions this isn't a significant point

[domi]

I believe Mux mentioned this somewhere, and please don't quote me on it, but it went about how the pistons are perfectly suitable, but the crown does not have the perfect profile for the job. It is non-interference for the most part, but the most dangerous aspect was already mentioned - if a camgear skips a tooth you'll be meeting pistons and valves and nothing good ever cam out of that...

[Mux213]

Domi, wasn't me I think.. I know very little about engine tuning on this level

[domi]

I'm so bad at searching forums, i can't find it =(
Anyway, one of the knowledgeable people made the comment about the valve pockets on the piston crown - they do differ and that is the main difference. Anyway there's a good enough chance you can find aftermarket pistons for the 16v that'd be more expensive, but worth the wallet-stretch...

[oldeskewltoy]

The question is vague.... BUT I'm using a 20V silvertop short block in my AE86... I refitted 16V OEM high compression pistons. The piston wrist pin is the same from the 20V and the 16V high comp, so it(16V high comp piston) just fits with no issues.

[woper]

Thanks for UR opinions. I know that there would be a collision when timing belt breaks, but if You want to have a comp. ratio 11:1, that doesn't metter which pistons you're running - even aftermarket forged items.

What about knocking? Do You think that capacity between piston&head won't be to small?


Cheers!

[Ivan141]

Why dont you just get ae92 high comp pistons (10.9:1) and just get the rest from milling the engine/head or a thinner headgasket? You can get the pistons for under 300 euro's these days, dunno about 20v pistons, but I daresay the 16v pistons will do the job better combined with a 16v head.

[woper]

16V pistons are ok but high comp. are 10:1 (low comp. 9.6:1). Even with 0,5mm head gasket, there will be ca.10.6:1. But maybe You're right. Why do risky experiments.
Are 20V rings interchangeable with 16V high comp rings? I'm asking 'cause I've got brand new genuine STD bore set for 20V. It would be nice to use them.

Cheers!