Pistons and rings
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Cast pistons are fine for engines that won't see nitrous or boost. Forged pistons are a better choice if the engine will see boost or nitrous due to the added durability. There are those who say using cast pistons and nitrous/boost is acceptable. And it is- providing the tune is spot on and the engine never sees detonation. If it does, the cast pistons will be the first thing to fail, and when they go they usually damage the bore and possibly the cylinder head as well. This is because cast and hypereutectic aluminum alloys are brittle and when they fail they tend to shatter into many pieces, where a forging will generally stay in one piece, with pinched ring lands or depressed crowns, etc. | Cast pistons are fine for engines that won't see nitrous or boost. Forged pistons are a better choice if the engine will see boost or nitrous due to the added durability. There are those who say using cast pistons and nitrous/boost is acceptable. And it is- providing the tune is spot on and the engine never sees detonation. If it does, the cast pistons will be the first thing to fail, and when they go they usually damage the bore and possibly the cylinder head as well. This is because cast and hypereutectic aluminum alloys are brittle and when they fail they tend to shatter into many pieces, where a forging will generally stay in one piece, with pinched ring lands or depressed crowns, etc. | ||
| − | The worst possible piston design if a dished piston is needed is a round dish with a 45 degree chamfer around the outer edge. That leaves a scant 1/2" band on the top of the piston to provide the quench effect, and that's just not enough. | + | The worst possible piston design if a dished piston is needed is a round dish with a 45 degree chamfer around the outer edge. That leaves a scant 1/2" band on the top of the piston to provide the squish/quench effect, and that's just not enough. |
[[File:Round dish sbc piston.jpg|500px]] | [[File:Round dish sbc piston.jpg|500px]] | ||
| − | A much better choice if a dished piston is needed is a reverse dome or D-cup type piston (the one below is for a SBC 383 stroker). | + | A much better choice if a dished piston is needed is a reverse dome or D-cup type piston (the one below, left is for a SBC 383 stroker). |
| − | [[File:KB P-N 135 SBC 383 PISTON.jpg]] | + | The round dish piston shown below right is a compromise between the D-cup and the undesirable type of round dish (shown above). As can be seen, the squish band is wider and the dish smaller in diameter,but deeper. This maximizes the quench/squish effect, but retains the "one size fits all" economy because one casting/forging will fit either side of the engine. |
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| + | {| | ||
| + | |[[File:KB P-N 135 SBC 383 PISTON.jpg]] | ||
| + | |[[File:H423NP.jpg|300px|center]] | ||
| + | |} | ||
==Dish volume== | ==Dish volume== | ||
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