What shape pistons do you think would flow the best and make a good swirl with aluminium 72cc dart heads with 215cc runners and 2.05 intake valves with huge lift (close to .600''); domes, flat top or dish (I'll have to use 64cc darts for dish pistons)? It's for a 383.

 

Flat or "D-cup" are more or less the same. The D-cup will have a squish area to correspond to the squish area on the head. The piston you want to stay away from are those with an "O" shaped dish, though you don't see those much anyway. These do not have an effective squish area.

Rich Krause

 

What kind of compression ratio are you interested in?

IMO, piston top needs to be selected for CR and flame travel.
Domes would be my last choice, and only if I needed them to get the CR after milling the 64 cc chamber heads.

 

With the big cam I'm useing I'm kinda stuck with 10:1 +

 

Ummm, I'm confused.

The more cam duration you have, the more static CR you need/can have, of course. As you get much over 10:1, probably dished pistons are out of the picture.

To clarify things, how about more specifics on the engine, cam timing, what you want to do with the engine (street, strip) etc.
What may be "huge" to you isn't necessarily that to others. Numbers help.

FWIW, the shape of the piston crown has very little to do with airflow into the engine or swirl.

 

a while back i saw somthing about JE making some called quench pistons that had these golf ball like dimples in them, but then agian quench and swirl aren't the same thing

 

in/out
234/245 duration at .05 114LSA
.560/.588
Flat tap hyd cam
That's a little big for street.

 

Mostly you choose a piston shape for flame travel across it. A domed piston with a low positioned spark plg (straight) will be less efficinet than a flat top with that same cumbustion chamber and plug position design, Now angleplug heads usually have a higher plug position so they can use a slight dome and still propogate the flame efficinetly, but the ideal situation for complete burn is a small chamber and a piston either flat or d cupped () to provide propper quench (and lower the compression) If youll notice alot of the big boys use all the way down to 48cc combustion chambers with a d shaped piston (recess). I remember in the early 70s (as a kid ) everyone wanted big ole pop-up pistons. Of course this was before they started making some real good combustion chambers.

 

So the best combustion would be 64cc heads with straight plugs and D dish pistons, no more than 8 or 9cc D cups( ).

 

AFAIC, this is a major reason the 18* heads became a reality. It allowed a shallower chamber roof, which gave a much smaller combustion chamber, which allowed big CR #s with small domes.

 

Sounds kind of tame to me. For what you are doing you shouldnt worry too much about piston design. You wont need a dome to get the compression you need and if you buy a good quality piston from JE or CP it will have a good design anyway. The most it will probably need is a little polishing and thats it. If you were gonna use a big dome then I would suggest making a mold of the chamber and having a custom piston made and then hand smoothing it but thats not in the realm of what you will need.