Compression is everything! It’s power. It’s torque, it’s fuel economy. Compression is excellent until you have too much of it. You want as much CR as the octane in the fuel you are running can tolerate (as much as you can get away with).
Based on build and fuel type, we determine how much compression our customers’ engines can tolerate. There are always variables to consider, which is why we get critical build info on the engine and the application. For example, 93 octane can tolerate more than 91 and race gas, and E85 can tolerate more than any gas at the local pump. The engine combination, the environment where you will be running and fuel quality dictate what you can get away with regarding the static compression ratio of your engine. Addressing the chamber volume of your heads (and head gasket thickness) are the largest variables to optimize compression ratio.
To establish our target chamber volume, we do some math that is based on an engine’s bore and stroke, piston dome or dish volume (zero if it’s a factory flat-top with no valve reliefs), head gasket thickness and diameter, and how far the piston is in or out of the hole relative to the deck of the block (deck height).
This data allows us to determine the combustion chamber volume we need to set to establish the final static CR of the build. There are numerous online calculators - we like the one CSG Network provides.
Since the size of the engine and pistons are typically fixed (in an existing build), we mill the chamber to get optimum engine CR for the best performance. Mamo Motorsports sells heads with different chamber volumes, and mills each head for each customer’s engine specs. That’s why we cc each head once the port and valve work is complete, allowing us to achieve the optimum CR for our customers’ engines, providing the highest amount of reliable power. It's one more example of #themamoadvantage