Quote Originally Posted by erik erikson
You are thinking like a true engine builder a person that does this for a living.
If you shove a very large dome in a combustion chamber sometimes it does work sometimes it does not.
Some problems are cam timing, L/S etc.
When you put the large dome in the combustion chamber you divide up the combustion chamber into different area's.
You will have lean area's and rich area's.
If you have a small combustion area you run the risk of "shrouding" the valves.
On the SBC 23 degree heads I will try and "roll the heads" meaning I will angle mill the heads from 23 degree's down to 20 3/4 degree's.
Not only does this increase my comp. ratio it also will help my heads flow better.
A 64 cc SBC head will be down in the 58 cc area.
In a 383 SBC this will put me up in the 12 to 1 comp. area.
A small 3 cc dome will put you at 13.3 comp. ratio which is enough for the averege bracket racer on gas.
The comp. ratio's have gotten crazy.
On a 410 down nozzle sprint car engine with a 13 degree ALL PRO head they are now running the comp. ratio at the 16.5 to 1 area.
When will it stop??
Great point Eric! Combustion chamber design,,,,although I'll admit this is 'over my head',no pun intended,,,,the hobbiest,on the average has no idea how important this is to producing power.WELL,,,the 'Mopar Nationals' are in town this weekend at National Trails Raceway and some of those Himee(spelled properly thank you) guys know a thing or two about chamber design giving an advantage.
In any machinery that uses 'combustion' to do work,the chamber design can make a world of difference. I used to be a furnace man and this applies even there,especially oil furnaces.
I love to see a chamber on one of those 16:1 CR drag cars.