This invention is the addition of a variable inlet valve damper to an internal combustion engine so that it can reduce the amount of fluid sucked into the engine by allowing some of the fluid to be pushed back out during the compression cycle. This is accomplished by delaying inlet valve 14 closing. The variable inlet valve damper is made up of damper cylinder 2, damper piston 4, check valve 6 which allows fluid into damper cylinder 2 but not out of damper cylinder 2, and control valve 8 which varies the flow out of damper cylinder 2, fluid storage tank 9, bracket 10, and attachment 11. Without the addition of the variable inlet valve damper, inlet valve 14 would open immediately when cam 18 urged it to open and would close immediately when cam 18 allowed it to from the urging of valve spring 16. With the addition of the variable inlet valve damper, the timing of when inlet valve 14 closes can be varied to optimize engine operation. With control valve 8 open all the way, the engine operates at full power because all of the working fluid stays in the engine. As control valve 8 closes the engine keeps less fluid, the power of the engine is reduced, and the efficiency of the engine is increased.