![]() Once you encounter valve float, it can be as minor as simply a loss of power, as the valves are no longer doing what they are supposed to do, when they are supposed to do it, or it can be so severely out of sync, that things start impacting one another. All those parts moving in unison make for a lot of reciprocating mass that have to be controlled at high-RPM. Using a disassembled single-cylinder engine as a demonstration tool, Fenske illustrates a typical in-block-cam, OHV valvetrain setup, with the lifter, pushrod, rocker arm, valve, spring, retainer, and lock. There comes a point where parts of the system lose direct contact with one another, and the valve movement is no longer directly related to the camshaft’s movement.” “The reciprocating mass can start to outrun the spring. You have a lot of mass in the system that is trying to change direction very quickly as you get into higher RPM,” Fenske explains. “The entire assembly has to reciprocate back and forth very fast. The first reason is uncontrolled valve events – also known as valve float. He then translates that into automotive V8 pushrod engines.Īs Fenske explains it, there are three major drawbacks when trying to get a pushrod engine to perform at high-RPM. However, Jason Fenske of Engineering Explained fired up his trusty video camera and dove deeper into the reasoning behind the statement that “Pushods can’t rev high.” Fenske starts with a cool overview of a disassembled single-cylinder engine, and breaks down how the rotating assembly and valvetrain work in unison, Barney-style. ![]() While the statement is mostly accurate, first, it’s relative, and second, it’s a generalization. ![]() ![]() ![]() One of those generalities is that pushrod engines aren’t meant to be RPM monsters. You probably also know most of the generalities associated with different engine types. Being an EngineLabs reader, you are probably more familiar than the average bear with how and why engines work. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |