Increasing the size of the inlet valve increases the amount of FAM that is allowed to enter the combustion chamber. Increasing this mixture flowing into the combustion chamber means that when the engine speeds are at the higher end of the scale the extra mixture is enough to fill the combustion chamber, unlike standard valves. This results in greater torque and power at higher revs for larger valves. At the lower end of the scale the larger inlet valves would result in a slight decrease in torque.
In normally aspirated combustion engines it is general practice to make the exhaust valve a smaller diameter than the inlet valve. This is because the piston forcibly expels the exhaust gases, whereas the inlet air is drawn in. On an engine where carburettors are fitted the largest pressure pushing into the cylinder is in the region of 15lb per square inch. On the exhaust side there is generally up to 80lbs per square inch in the cylinder when the exhaust valve should not be made at the expense of the intake valves. This is not the case when dealing with supercharged or turbo charged engines, where the FAM is forcibly brought into the cylinder.
Three Angled Valve Seats help the flow of the mixture into the combustion chamber because of their modified shape. As their name suggests these valve seats are made up of three angles. The various angles allow less obstruction to the flow of air fuel mixture into the combustion chamber. This improves the breathing of an engine and therefore the power output.