camshaft theroy
06-08-2009, 12:34 AM
#1
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camshaft theroy lift on these 2 cams are identical
FM14 - 232/234 600/600
Lunati - 237/243 600/600
in part- im wondering which more greatly affects the way a cam makes power - a slight difference in lift or duration.
lets also say the flipside if i had 2 cams with the same duration on both sides but a marginal difference in lift (same LSA, advance etc)
ex. 233/239 600/600
233/239 609/609
what kind of differences can u expect?
+ i understand the idea of grinding advance into the cam to lower max hp & tq rpms, but of all the research ive done i still cant determine affect of LSA on powerband
cam # 1 237/242 603/609 111
cam # 2 237/242 603/609 114
differences??? (i notice that stock cams tend to be around the 117-119 LSA range & race cams tend to be closer to a 110 or so)
FM14 - 232/234 600/600
Lunati - 237/243 600/600
in part- im wondering which more greatly affects the way a cam makes power - a slight difference in lift or duration.
lets also say the flipside if i had 2 cams with the same duration on both sides but a marginal difference in lift (same LSA, advance etc)
ex. 233/239 600/600
233/239 609/609
what kind of differences can u expect?
+ i understand the idea of grinding advance into the cam to lower max hp & tq rpms, but of all the research ive done i still cant determine affect of LSA on powerband
cam # 1 237/242 603/609 111
cam # 2 237/242 603/609 114
differences??? (i notice that stock cams tend to be around the 117-119 LSA range & race cams tend to be closer to a 110 or so)
06-08-2009, 12:55 AM
#2
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You may want to check the spelling of the title before posting because it take a Moderator to correct it lol.
The duration will greatly affect the performance more so than the lift. The max lift is only for a very short duration. How long the valves are open for will have a much greater effect on power. Also the design of the lobe (ramp rate) will make a difference more then the max lift.
Are you looking to buy a cam? If so determine what you goal is. There are plenty of threads that you can read up on cam theory check the stickies.
The duration will greatly affect the performance more so than the lift. The max lift is only for a very short duration. How long the valves are open for will have a much greater effect on power. Also the design of the lobe (ramp rate) will make a difference more then the max lift.
Are you looking to buy a cam? If so determine what you goal is. There are plenty of threads that you can read up on cam theory check the stickies.
06-08-2009, 07:06 AM
#3
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Cam theory at first seems overwhelming, but here are a few pointers.
There are a number of online Cam Timing and Overlap Calculator's. I use one designed by Pat Kelly which is either linked via the stickies of 'Google'.
It allows you to input differing intake/exhaust and LSA combinations and the 'ramp rate' of the cam lobe(s).
Ultimately, you will see that the Intake Valve Closing (IVC) is one of the most important valve events that determines your power band. Close it earlier, and the cylinder pressure (power) peaks earlier. Close it later..power band peaks later.
Both duration and LSA determine the IVC. They are differing variables, but in reality have equal weight in determining the IVC. Don't think of LSA as something uniquely different from duration. They are all inter-related.
For an LS1 with a LS6 manifold and stock heads, it becomes hard to get any additional power from a cam by lift alone. Also, once the IVC begins to exceed 42-46 degrees you arguably begin to lose lower end torque and may not even gain further top-end power.
That is the shortest and most condensed version of cam theory I can give you. You can always stock up on a ton of books when you have nothing to do, or if you have the mechanical skills to install a cam..just start doing it.
Hope that helps.
..WeathermanShawn..
There are a number of online Cam Timing and Overlap Calculator's. I use one designed by Pat Kelly which is either linked via the stickies of 'Google'.
It allows you to input differing intake/exhaust and LSA combinations and the 'ramp rate' of the cam lobe(s).
Ultimately, you will see that the Intake Valve Closing (IVC) is one of the most important valve events that determines your power band. Close it earlier, and the cylinder pressure (power) peaks earlier. Close it later..power band peaks later.
Both duration and LSA determine the IVC. They are differing variables, but in reality have equal weight in determining the IVC. Don't think of LSA as something uniquely different from duration. They are all inter-related.
For an LS1 with a LS6 manifold and stock heads, it becomes hard to get any additional power from a cam by lift alone. Also, once the IVC begins to exceed 42-46 degrees you arguably begin to lose lower end torque and may not even gain further top-end power.
That is the shortest and most condensed version of cam theory I can give you. You can always stock up on a ton of books when you have nothing to do, or if you have the mechanical skills to install a cam..just start doing it.
Hope that helps.
..WeathermanShawn..
