Jay Allen
02-21-2006, 01:04 AM
Currently there is a post in another Forum of this board dealing with camshafts. The combination is wacked due to the fact that pieces were chose that do not belong together in a land yacht.
The subject has turned into a camshaft discussion. That's good! But the guy runs NOS. People are spouting off about *Lobe Separation Angle* (LSA) and I want to discuss LSA.
You have the intake opening @ .050" and the intake close @ .050". Together these items make duration @ .050" and the intake center (IC).
You have the exhaust opening @ .050" and the exhaust close @ .050". Together these items make duration @ .050" and the exhaust center (EC).
Anyone who knows anything about camshafts goes about it from this avenue. They may look at different aspects of the engine in the designing phase by looking at velocity, pressures, cylinder pressure, etc, but in the simplest of terms, this is how it starts.
Basic remedial math here.
The (IC) + the (EC)/(2) = LSA
Thus, the average of the centers is the LSA. When you speak to a guy who claims that camshafts aren't voodoo and speaks in terms of LSA, well, he's very uneducated. When a person says LSA, what is he really saying?
Example.
I design a camshaft and I feel as though the events at .050" need to be:
IO = 15
IC = 55
EO = 66
EC = 14
Now put these together. The in @ .050" = 250* and the ex @ .050" = 260*. These events make the IC = 110 and the EC = 116. Thus.......
110 + 116 = 226.......226/2 = 113 LSA
In the above example, those EXACT opening & closing events yield the specs above. Period. Now when a guy comes along and says that a 113 LSA is a NOS cam, a motor cam should have tighter LSA (or more common going from motor to NOS) that ALL you need to do is change the LSA, you cannot just magically change the LSA. Its impossible.
Backwards. 110 + 116 = 226/2 = 113 EVERYTIME. But if I come at it and say I want a 113 LSA, how many different combinations of numbers can you have and get to 113?
Infinate.
Just a little FYI.
Enjoy!
The subject has turned into a camshaft discussion. That's good! But the guy runs NOS. People are spouting off about *Lobe Separation Angle* (LSA) and I want to discuss LSA.
You have the intake opening @ .050" and the intake close @ .050". Together these items make duration @ .050" and the intake center (IC).
You have the exhaust opening @ .050" and the exhaust close @ .050". Together these items make duration @ .050" and the exhaust center (EC).
Anyone who knows anything about camshafts goes about it from this avenue. They may look at different aspects of the engine in the designing phase by looking at velocity, pressures, cylinder pressure, etc, but in the simplest of terms, this is how it starts.
Basic remedial math here.
The (IC) + the (EC)/(2) = LSA
Thus, the average of the centers is the LSA. When you speak to a guy who claims that camshafts aren't voodoo and speaks in terms of LSA, well, he's very uneducated. When a person says LSA, what is he really saying?
Example.
I design a camshaft and I feel as though the events at .050" need to be:
IO = 15
IC = 55
EO = 66
EC = 14
Now put these together. The in @ .050" = 250* and the ex @ .050" = 260*. These events make the IC = 110 and the EC = 116. Thus.......
110 + 116 = 226.......226/2 = 113 LSA
In the above example, those EXACT opening & closing events yield the specs above. Period. Now when a guy comes along and says that a 113 LSA is a NOS cam, a motor cam should have tighter LSA (or more common going from motor to NOS) that ALL you need to do is change the LSA, you cannot just magically change the LSA. Its impossible.
Backwards. 110 + 116 = 226/2 = 113 EVERYTIME. But if I come at it and say I want a 113 LSA, how many different combinations of numbers can you have and get to 113?
Infinate.
Just a little FYI.
Enjoy!