Cam seperation angle effect on boost ?

I got a 14 degree in a screw blown hemi how would it effect it to go to a 16 or 18 degree ?

 

Lobe Separation angle

If you are talking going 2-4 deg up from 114 LSA, I would think it would increase your cylinder pressure, I'm no cam expert so there may be more changes it will make. You say what will it do to boost, I would say nothing, but IMO it will increase cyl pressure. Please don't ask how much because I have no idea


Corey

 

The intake closing after bottom dead center directly effects cranking compresion. More seperation might give you more boost because of less overlap.

 

If you have two cams with the same duration, one with 114 seperation and one with 118 and you install the both straight up;114 @ 114 and 118 @ 118 the one with 118 will have less effective compression because the intake closes later. http://www.kb-silvolite.com/calc.php?action=comp

 

Cam

Just proves the statement that I'm not a cam expert. Interesting.

Corey

 

That is true, you move your IVC 4 degrees farther, which reduces effective compression, but you lose 8 degrees of overlap too. If I had a 114lsa and a 116lsa, both installed at 112ic, the 116 is going to generate more cylinder pressure because the IVC doesn't move, but the overlap closes up 4 degrees.

So you see, Corey, you were right too.

-Brian