Camshaft lobe overlap ??
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
It's pretty simple. And it's intuitive when you think about it. If the intake valve opens at 21 degrees BTDC, yet the exhaust valve doesn't close until 20 degrees ATDC, then you have 41 degrees of overlap. Simply add those two numbers together. They're both right there on the cam card. Changing the Lobe Separation will increase or decrease the overlap by changing when those two valve events occur relative to one another. Changing the Lobe Center Angle will simply shift both numbers one way or the other, but the overlap will remain the same.
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
Originally Posted by SWCDuke
It's not simple. I posted a more detailed discussion to the same queston in the C2 section.
Duke
Duke
In other words, apples to apples comparison. Take a cam, and all else being the same, have it ground with more or less lobe separation and the overlap will change.
There is of course no way to tell anything about the overlap of a cam just by looking at the LSA (i.e. 110 vs. 114), and therefore you can't tell anything about the difference in overlap between two different cams simply by looking at the LSA.
Dan
