390 w/open chamber heads
My question is this....I've read a lot about quench and the closed chamber heads. With the open chamber 596 castings I'm not going to get any quench BUT since I have all that stroke I should have no problem getting good compression (9.5 to 1). In fact, I'll have to be careful not to get a high dome so that can't run on pump gas.
The 390 will go into a '69 Barracuda. I guess I'm worried about getting "ping" (detonation) since I won't have any quench.
strokers usually don't need dome pistons, in fact dished pistons are the most common type for stroker engines.
Let me try to explain why.
As I'm sure you know, compression ratio is a comparison between a piston's displacement and the size of the combustion chamber.
for example if you have an engine with 10:1 compression in a standard stroke 318 you have 39.75cubic inches of swept displacement per cylinder. and an effective chamber volume of 3.975 cubic inches.
If you stroke that motor to 390 you suddenly have a displacement of 48.750 and in order to maintain a compression ratio of 10:1 you would need a chamber volume of 4.875cubic inches.
Obviously 4.875 is bigger than 3.975. Therefore if using the same cylinder heads, the stroker motor will need to have the piston further down the bore at top dead center, allowing the remaining bore above the piston to act as part of the combustion chamber.
For this reason you will need pistons that are specifically designed for a stroker engine.
9.5:1 will be fine with an open chamber, all day, every day. towing, racing, cruising. whatever. They make these pistons and you can get them off the shelf.
