combustion chamber design?

[my72vette454]

I dont know much about about chamber design and quench area to control detonation when using forced induction so I am wondering what to look for on a big block chevy as far as using open chamber heads vs closed chamber and the shape of the piston in relation to the chamber. As I understand it, open chamber heads will flow a little better because the valves are unshrouded a little more. Is a flat top piston better than a domed piston, assuming you can get the proper compression ratio with domed pistons? From what I have read, 8.5 to 1 ratio seems to be a good ratio for forced induction on the street/strip. Would love to hear some thoughts on the subject.



Thanks,
Mike

[ProdigyCustoms]

In the old days, we thought Pop ups that had shape similar to the combustion chamber was the hot set up to get a nice square quench. Now we have learned a good chamber works best with either a flat top, or even dish, then a pop up.
As far as detonation, try to keep the piston at zero deck, and do not use extra deck height to lower compression. This has a tendancy to make the pistons hot and is a big cause of rattle (detonation).
Open chamber and flat tops would be the way to go.

[justanova]

In the old days, we thought Pop ups that had shape similar to the combustion chamber was the hot set up to get a nice square quench. Now we have learned a good chamber works best with either a flat top, or even dish, then a pop up.

that is precisesly what my machinist says, and he builds a lot of sprintcar motors and dirt track alcohol motors, he recommended for our 406 (a 14:1 alcohol motor) to use flattop pistons and a 50cc combustion chamber.

I know this is for a different styl engine all together but the principle is the same.

my .02