ooo you need something like an engineering degree to crunch those numbers.

You would have to know the flow rates of the new heads, the various pressures involved with the springs and how that pressure translates as friction on the camshaft, and if you change the cam out then you are adding more air/fuel into the mix which changes cylinder temperatures and many many many other factors.

I am thinking of this stuff off the top of my head but, I think the way they estimate horsepower is through experience with the parts and that particular engine and engine combination. It takes eons of experience to get a really accurate power estimate.

So to answer your question that formula is WAY too basic to add in various variables to see how they change up the answer.




Blastantly pirated from wikipedia... MEP is (Mean Effective Pressure)

MEP is a useful comparison tool between different engines, and is a good indicator of the level of performance achieved by the designer and manufacturer. It measures the efficiency of the conversion from the indicated mean effective pressure in the cylinder to the output shaft and the level of pressure attained in an engine. It is important to remember that the values produced by the formula are for theoretical analysis only, and do not reflect the actual pressures inside an individual combustion chamber.

-CJP