</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MyLS1Hauls:
<strong> .... The nice thing about the XE lobes is that they have less advertised duration for the same .050", so you can run a bigger cam and still retain drivability.... </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That is exactly why I would not choose the crane cam listed above, and why I sugested the XE earlier. The Comp XE lobe has fast ramps - they open, reach full lift, and close faster. That means duration wise, they act like smaller cams yet still let in more A/F mix. The downside to this is that valvetrain noise may be higher and life may be shorter.

The crane cam looks like it has slower lazy ramps. Even though it shows to be a 208/216 @ .050 lift, it has a larger duration @ .006 lift. This means it starts opening earlier and closes later causing more overlap and loss of low end power.

Durations are often referenced at .050 lift, so its easy to compare cams of different grinds. But this is only at one lift level, so it doesn't say much about the lobe. Look at the cam cards for the advertised duration as well. It give you an idea of what degrees the valves open up and close.

EXAMPLE- Two cams: Crane 208/216 .530 and the Comp 212/218 .522/.529

The crane looks like a smaller cam, right? Its durations are smaller. Wrong. The crane has an advertised duration of 276 - 284 while the comp is 265 - 271. That means the Crane starts opening its valves sooner than the Comp cam and closes them later. Thats a direct reflection on the comp ramp being faster. This will let the comp cam keep more low end power yet still breathe in the upper rpms.