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View Full Version : 03/04 4v NMRA factory stock heads



na svt
07-02-2007, 10:50 PM
These heads are from Shawn Johnson's 96 NMRA Factory Stock Championship car. All the work was done by Modular Performance.

The valve and springs are FR500 parts and the retainers are titanium. Up to 1996, the 4v motors were allowed to have the same combustion chamber volume as the 2v engines, which is 44cc. With the smaller chamber size these heads with flat top pistons result in an 11.8 to 1 compression ratio (give or take a little). On a stock longblock these heads will make the compression ratio about 1 point higher than stock, so roughly 10.8 to 1.

The heads were selected from a large number of 03/04 castings and selected for their high flow numbers.

They are in superb condition, ready to bolt on and would be a great mod for a stock longblock 99/01 or Mach 1 engine.