Hoser peer check here. ;)
You used the formula for circumference (the distance around a circle)
instead of the area of a circle.
(What triggered me was the fact that your first value was 12.5 square inches. That is ~ a square the size of 3" by 4".)
I used this site to refresh me on my circle formulas.
http://www.1728.com/diamform.htm
Circle Area = Pi x radius^2
Spoken: Pi times radius squared where Pi is 3.1415926
Radius is 1/2 of the diameter.
A recalc shows:
Value___Stock_____Hoser____Aussiedune
Radius___0.97______1.03_______0.95
Area ____2.956_____3.333______2.835
2 holes___N.A.______6.666______5.670____The Area times 2
Compared to Stock Units in Square inches Larger than stock
________Stock_____Hoser____Aussiedune
__________0________3.71_______2.71
Percentage wise: This is how I calculate it.
I divided the total area of Hoser or Aussiedunes openings by the
area of the stock opening and multiply by 100 for percentage.
This tells us that Hoser's is 225% The volume of stock.
________Stock_____Hoser______Aussiedune
__________0_______225.5%______191.8%
But if we take away the 100% volume for the stock opening we get how much larger each lid's dual openings combined as compared to stock.
________Stock_____Hoser______Aussiedune
__________0_______125.5%_______91.8%
So hoser's is 125% larger than stock. And Aussiedunes is 91.8%
As a side note since we're comparing two sets of volumes and the formulas are the same. The math reduces to a formula that doesn't even need Pi.
Test Radius Squared times 2 all divided by Stock Radius Squared will give us the same percentages.
Make sense? Do others compare percentages differently?
Another interesting fact would be to measure the air box air pressure on the same
Engine across RPMs. Measure this for both lids and see that the stock has a much more negative pressure than the modified lids. And plot this as a comparison with a static atmospheric air pressure.