Originally Posted by bgoodsoil
I think what you're calling a gudgeon pin we call a wrist pin. If so, I get what you're saying there. What do you mean by ring lands? The grooves for the rings? Maybe the stock pistons had acres of useable space so they're not pushing the limit on that? I thought Siebenrock's kit was well-vetted. I wonder who designed that thing?
What are AFRs?
Gudgeon pin is wrist pin but I refuse to Americanise myself. Therefore I see colours, I eat doughnuts, roll on tyres not tires, have silencers not mufflers, the hood is a bonnet, the boot is what you call a trunk and all the rest of the grammatical differences. Engines also have big ends here...
Ring lands are the areas between the piston rings. They are thinner the closer the rings are to each other, thus more likely to break. The land between the crown and the top ring is the most easily damaged as if the crown deforms under detonation etc the thinner it is the more likely it will either break away or deform and pinch the ring.
The bigger the ring lands the more stable the piston will be, the further the top ring is away from the combustion chamber the less nasty forces it will see and will run cooler but the piston hotter...
Small ring lands can distort easier and with that comes all sorts of issues, from ring flutter to pinching.
The other factor is of course ring numbers, a lot of racing engines will perhaps only run 1 compression ring and an oil scraper or 2 compression rings and no scraper. Race engines are throw away commodities generally so damn the emission compliance, economy and longevity.
AFR air - fuel ratios. The biggest force on whether an engine lives, dies, makes power or empties the wallet.