pi swap compression ratio

[eksplosivejoe13]

if i grind off the swirl dam on some PI heads and install them in my 96, anybody have any idea what the compression ratio would be? I know stock PI heads would give about a compression ratio of about 10.5:1.

Any ideas?

 

[Ninety8stang]

How come you are wanting to lower the compression? Taking out the swirl is going to drastically alter the way the air enters the combustion chamber. Its made so that when the air enters the combustion chamber it is vortexed and allows more air to flow, but I'd say it would lower it at least half a point or so but wouldn't be very beneficial.