Thnaks for getting me the number. In order to get an idea of what the change will be to the compression ratio of the
Engine and the cankng presure reading wll will first calculate the CCR ( corrected compression ratio) using your 46.44 and some numbers I have from previous work to draw a conclusion of the effect for fun. Your 46.44mm from exhaut open to deck using a stock base gasket puts you right around 92 degrees ATDC (after top dead center). With the speed head with the 49 cc dome and the numbers I have we can calculate the base line CCR.
We will use the formula of VTDC + swept volume /VTDC.
VTDC= volume at top dead center or the pisotn at TDC (Top Dead Center) and the total volume above it.
The swept voulme is the amount of cc of the cylinder less piston crown volume at the point which the piston crowns edge shuts off the exhaust port.
First calculate you swept volume. bore x bore x .0007854 x stroke
Take you piston size which appears to be 80 mm and use that as your bore and use your 46.44 as your stroke.
That will give you your swept volume
For the VTDC we will use a number I have and for that, use 38
Now you can use the the change in the head to see the difference. Example would be if speed is going to fit the head with a 47cc in place of the 49cc subtract the difference for the 38 and recalculate. Also if there some decking and dome change ask speed for the decking number or the new head total cc to use. The 38 for the formula is based on a 49 cc head and stock head gasket.
Post up her/your results.
Then you can compare the cranking compression number at your base line CCR and the cranking compression at the new CCR number for your altitude. Then we can compare to a lower altitude numbers I have. The compariosn between CCR and cranking are not revelant other than fun facts.
The rise in CCR will have an effect on your pistons thermal loading and the wave speed in the pipe at that port time opening,nothing too major just related fact.
Take a pic of her/your work and post your results.