In conjunction with a thread I started on the next step in my “modding” where I was talking about going with a modified head, https://www.motoringalliance.com/threads/next-step-in-my-modding.30837/page-2#post-408719 In this thread I would go more into the general details of the head and the main components involved; the ports, the valves, and the cam shaft, First, an engine brings air in and pushes it out, it’s a pump. The more air that can be processed the more power being generated. There are two types of engines, aspirated – bringing air in by the shear suction created by the rotating pistons and the exhaust pressure, and forced induction – supercharger/turbocharged where the suction created by the pistons/exhaust is supplemented by a pump pushing/pressurizing the air. The air that the engine processes is brought into and exhausted via openings on the front and back of the engine. These openings are called “ports.” The larger the ports, the more processed. The size and shape of the port along with the smoothness or the port walls all affect airflow. In some instances, having a change in the shape of the port can impact air flow. These shape changes can either decrease or increase the velocity that the air can travel through the port. The finish of the port wall, roughness, also impacts velocity. The intake manifold bolts to the engine allowing a pathway from the air filter into the engine. The exhaust manifold or header is also bolted to the engine and allows the exhaust gases to pass through the catalytic converter and then out the mufflers. If the engine head ports are enlarged than the ports on the intake and exhaust manifolds should match for the best performance. Thumper Performance, Way Motors and Sneed4Speed sell ported intake manifolds. Local area machine shops also may be able to perform the porting. We move to the next step of the air process, the valves. Intake valves are normally larger than exhaust valves that you can see in the picture below. A valve is a doorway into the combustion chamber and the valve spring is what keeps that door closed. A valve has two parts, the stem and the head. The diameter of the stem and angle that the bottom of the head is shaped impacts the amount of air that can pass through the “door.” A lighter valve can have a smaller spring. These weight decreases means the engine requires less force to operate and results in a faster revving motor A valve can be made lighter by shortening the stem length and also by drilling out the center. Valve weight can also be affected by the metal alloy used. The alloy being used also affects the ability of the valve to handle the heat generated by the engine combustion cycle. Some valves are coated and some are drilled and filled with a different material all in an attempt to address either intake or exhaust impacts. Below are two informative articles on valves. http://www.enginebuildermag.com/2006/12/performance-valves/ http://www.sbintl.com/tech_library/articles/understanding_valve_design_and_alloys.pdf The final piece of this process is the camshaft. The Gen1 MINI has one camshaft while the Gen2 and 3 cars have dual camshaft engines. A camshaft is a long hardened steel bar that is machined to produce a particular shape. The camshaft is attached via a chain to the crank pulley that rotates the cam shaft, forcing it to open and close the valves that are held shut by the valve spring. As the crankshaft rotates the camshaft is turned by the drive chain. The lobes on the cam make contact with the rocker arm (some may call this the lifter) that pushes down on the valve stem thereby opening the valve allowing air either in or out of the cylinder. Most camshafts upon purchase have a “Cam Card” or spec sheet. This card should provide; 1.) Lift - The amount in inches/mm that that cam lobe will push down on the valve stem. 2.) Lobe Separation and Overlap –To function properly the intake and exhaust valves are open at the same time for a very short duration of time. Low-end Torque will be increased by a larger (more degrees) lobe separation. A narrow/smaller lobe separation will decrease low end torque but provide more top end horsepower. This will have a more rough idle. 3.) Center Line – These values expressed in degrees are used in calculating the Lobe Separation. 4.) Duration and Cam Degre eing/Timing– These values are also expressed in degrees. This measurement is based on crankshaft location, not camshaft rotation. This correlates to when the valve opens in relationship to the position of the piston. I have included two informative videos for you. The second video utilizes the push-rod engine but the discussion can be easily applied toward our overhead camshaft engines. I have a RMW Dominator Cam, it came with no Cam Card. From information on the RMW Site it appears to have 250 deg duration and .400 lift. What it does not provide is what the duration reference point is that would be designated by @xxxxxx inches/mm. It also does not provide the Lobe Separation or Overlap.